Introduction: Why Proper Mounting Matters More for Thermal Scopes

Thermal rifle scopes represent significant investments—the GTGUARD X350L and X650L cost $1,299-$1,999. Proper mounting isn't just about preventing equipment damage (though that matters); it's about maximizing the performance you paid for. An improperly mounted thermal scope suffers from:

Degraded Image Quality: Misaligned mounting causes optical stress, reducing thermal image clarity and potentially damaging sensitive microbolometer sensors

Zero Loss: Insufficient or uneven ring torque, improper ring spacing, or inadequate rail preparation causes zero shift during recoil, wasting ammunition and missing opportunities

Equipment Damage: Over-torqued fasteners crush thermal scope housings; under-torqued mounts allow movement that breaks internal components during recoil

Safety Risks: Loose thermal scopes can shift during shooting, potentially causing eye injuries from improper eye relief or scope movement

This guide ensures your X350L or X650L mounting achieves professional standards, delivering the precision and reliability your investment deserves.

Understanding Thermal Scope Mounting Systems

Picatinny vs. Weaver Rails

Most modern rifles feature Picatinny (MIL-STD-1913) rails—the industry standard for tactical and precision rifles. Understanding the difference prevents purchasing incompatible mounting hardware:

Picatinny Rail Characteristics:

• Standardized slot width: 0.206 inches
• Slot spacing: 0.394 inches center-to-center
• Cross-bolt recoil lugs engage slots for positive retention
• Universal compatibility with Picatinny-spec rings and mounts

Weaver Rail Characteristics:

• Similar appearance to Picatinny but non-standardized slot spacing
• No cross-bolt engagement (relies on friction only)
• Found on older rifles and budget firearms
• Weaver rings often fit Picatinny rails; Picatinny rings may not fit Weaver

For X350L and X650L: Use Picatinny-compatible rings. These scopes require secure, repeatable mounting that Weaver systems don't reliably provide.

One-Piece vs. Two-Piece Rings

One-Piece Cantilever Mounts:

• Integrated base and rings in single unit
• Provides consistent ring spacing (no adjustment)
• Generally more rigid than two-piece systems
• Easier to install (fewer components)
• Limitation: Fixed eye relief position—must fit your scope and rifle combination

Two-Piece Rings:

• Separate front and rear rings
• Adjustable spacing accommodates various scope lengths
• More versatile across multiple rifles
• Requires careful installation to ensure proper alignment

For X350L/X650L: Two-piece rings recommended. The 190mm length (X350L) and slightly longer X650L benefit from optimized ring spacing that cantilever mounts may not accommodate perfectly.

Ring Height Selection

Thermal scopes require appropriate ring height for proper eye relief and cheek weld:

Ring Height Factors:

• Objective lens diameter (35mm for X350L, 50mm for X650L)
• Rifle stock comb height
• Desired eye relief (38mm for X350L and X650L)
• Presence of rail-mounted accessories (backup sights, laser devices)

General Guidelines:

• Low Rings (0.87-1.00" center height): Inadequate for most thermal scopes; objective lens contacts barrel
• Medium Rings (1.00-1.26" center height): Work for X350L on most rifles with moderate comb height
• High Rings (1.26-1.50" center height): Recommended for X650L due to larger 50mm objective; also necessary for rifles with high-comb stocks
• Extra-High Rings (1.50"+ center height): Required for AR-platform rifles achieving proper cheek weld with thermal scopes

X350L Recommendation: Medium rings (1.00-1.26") for bolt-action rifles; high rings (1.26-1.50") for AR-platforms

X650L Recommendation: High rings (1.26-1.50") for bolt-action rifles; extra-high (1.50"+) for AR-platforms

Material Considerations: Steel vs. Aluminum

Steel Rings:

• Superior recoil resistance
• Heavier weight (typically 6-10 ounces)
• Better suited for heavy-recoiling magnums (.300 Win Mag, 7mm Rem Mag)
• Coefficient of thermal expansion matches steel receiver
• Cost: Typically $80-$150 for quality sets

Aluminum Rings (7075-T6):

• Excellent strength-to-weight ratio
• Lighter weight (typically 3-6 ounces)
• Adequate for moderate recoil (.308 Win, 6.5 Creedmoor, 5.56 NATO)
• Minor thermal expansion difference vs. steel receiver (negligible in practice)
• Cost: Typically $100-$200 for quality sets

For X350L/X650L: Either material works excellently. The X350L weighs 550g (19.4 oz); X650L weighs ~600g (21.2 oz)—both relatively light for thermal scopes. Aluminum rings reduce overall system weight; steel provides maximum security for magnum-caliber rifles. Choose based on rifle caliber and personal preference.

Required Tools and Materials

Essential Tools

Torque Drivers:

• Fat Wrench (adjustable 15-80 in-lb range) or equivalent
• Bit set including Torx T15, T20, T25, hex 3mm, 4mm, 5mm
• Critical: Proper torque prevents under-tightening (allows movement) and over-tightening (crushes scope tube)

Cleaning Supplies:

• Isopropyl alcohol (90%+ concentration)
• Lint-free cleaning cloths or patches
• Degreaser (for removing factory oils from new rings/rails)
• Cotton swabs for detail cleaning

Alignment Tools:

• Scope ring alignment bars or level
• Wheeler Engineering Scope Ring Alignment Kit or equivalent
• Bubble level (for leveling reticle to action)

Fasteners:

• Blue Loctite 242 threadlocker (removable strength)
• Anti-seize compound (for steel rings on aluminum rails—prevents galling)

Optional But Recommended

Reticle Leveling Tools:

• Scope tube-mounted bubble levels
• Reticle leveling devices (Segway Scope Leveling System, etc.)
• Plumb bob for establishing vertical reference

Bore Sighting Tools:

• Laser bore sighter for your caliber
• Mechanical/optical bore sighters
• Collimator for zeroing without firing

Safety Equipment:

• Safety glasses (prevents chemicals/debris contact)
• Nitrile gloves (keeps oils off scope surfaces)

Step-by-Step Mounting Procedure

Phase 1: Rail Preparation

Step 1.1: Inspect Picatinny Rail

Remove any existing rings or accessories from rail. Inspect for:

• Burrs or raised metal at slot edges (file smooth if present)
• Damage to cross-bolt slots
• Bent or damaged rail sections
• Loose rail mounting screws

Action: If rail shows damage, replace before mounting expensive thermal scope.

Step 1.2: Clean Rail Surface

1. Apply degreaser to lint-free cloth
2. Wipe entire rail length, removing factory oils and debris
3. Follow with isopropyl alcohol wipe
4. Allow to air dry completely (2-3 minutes)
5. Inspect for remaining residue—repeat if necessary

Why This Matters: Factory oils prevent proper Loctite adhesion; debris causes uneven mounting surfaces

Step 1.3: Verify Rail Mounting (If Applicable)

For removable Picatinny rails (common on bolt-action rifles):

1. Remove rail from receiver
2. Clean receiver mounting surface and rail bottom
3. Apply thin layer of blue Loctite to mounting screws
4. Reinstall rail with appropriate torque (typically 25-30 in-lb—verify manufacturer specification)
5. Allow Loctite to cure 24 hours before proceeding

Critical: Loose rail mounting causes entire scope system to shift—no amount of ring torque compensates

Phase 2: Ring Installation

Step 2.1: Determine Ring Spacing

1. Place X350L or X650L on padded surface
2. Position rings on rail at approximate locations
3. Place scope in rings (don't tighten)
4. Verify:
   - Front ring positioned near front of scope tube (not on tapered section)
   - Rear ring positioned on cylindrical scope tube section
   - Eyepiece extends past rear ring allowing 38mm eye relief
   - Both rings on flat scope tube sections (not bell or eyepiece)

X350L Ring Spacing: Approximately 3.5-4.5 inches center-to-center optimal

X650L Ring Spacing: Approximately 4-5 inches center-to-center due to longer scope body

Step 2.2: Install Ring Bases

1. Remove ring top caps
2. Position ring bases at determined locations
3. Ensure cross-bolt recoil lugs engage Picatinny slots
4. Hand-tighten base mounting screws initially
5. Apply 2-3 drops blue Loctite to each screw thread
6. Torque base screws to specification:
   - Steel rings: 55-65 in-lb typical
   - Aluminum rings: 45-55 in-lb typical
   - **Verify your specific ring manufacturer specification**
7. Allow Loctite to cure 4-6 hours before proceeding

Common Mistake: Over-torquing aluminum ring bases strips threads. Under-torquing allows base movement. Use proper torque wrench.

Step 2.3: Check Ring Alignment

Before placing scope in rings, verify alignment:

1. Install ring top caps loosely
2. Insert ring alignment bars (or use commercial alignment kit)
3. Observe gap between bars:
   - No gap = perfect alignment
   - Small gap (<0.003") = acceptable
   - Large gap (>0.003") = requires correction

4. If misalignment detected:
   - Loosen base screws slightly
   - Adjust ring positions
   - Retorque base screws
   - Recheck alignment

Why Alignment Matters: Misaligned rings stress scope tube when cap screws tighten, potentially damaging X350L/X650L's precision thermal imaging system

Phase 3: Scope Installation

Step 3.1: Prepare Scope

1. Remove lens caps from X350L or X650L
2. Clean scope tube exterior with isopropyl alcohol
3. Inspect scope tube for:
   - Damage or dents
   - Previous ring marks (if used scope)
   - Foreign material on tube
4. Power on scope, verify normal operation
5. Set lowest magnification (2× base for X350L/X650L)

Step 3.2: Initial Scope Placement

1. Place scope in ring bases (caps still removed)
2. Position scope for proper eye relief:
   - Mount rifle in shooting position
   - Adjust scope fore/aft until thermal display fills eyepiece view at 38mm distance
   - Typical position: Eyepiece 3-4" from rear of receiver

3. Verify scope position doesn't:
   - Contact handguard, foregrip, or barrel
   - Prevent bolt operation (bolt-action rifles)
   - Interfere with charging handle (AR-platform)
   - Block ejection port

X350L/X650L Specific: 38mm eye relief measured from rear eyepiece lens to shooter's eye. This distance provides full thermal display view without vignetting.

Step 3.3: Level Scope Reticle

Critical for accurate long-range shooting:

1. Ensure rifle is level:
   - Use rifle vice or stable rest
   - Place bubble level on flat receiver surface or Picatinny rail
   - Adjust until level

2. Level scope reticle:
   Method A (Anti-Cant Level):
   - Attach bubble level to scope tube or rail
   - Rotate scope in rings until reticle level matches rifle level
   
   Method B (Plumb Bob):
   - Hang plumb bob 25+ yards downrange
   - Align thermal reticle vertical crosshair with plumb line
   - Adjust scope rotation until aligned

3. Visual confirmation through thermal scope:
   - Reticle vertical line should appear truly vertical
   - Reticle horizontal line should appear truly horizontal

Why Leveling Matters: Canted reticle causes increasing horizontal error with distance and holdover. At 300 yards with 5° cant, expect 5+ inch horizontal deviation.

Step 3.4: Install Ring Caps

1. Place ring top caps on scope
2. Apply 1 drop blue Loctite to each cap screw thread
3. Hand-tighten all cap screws until light resistance felt
4. Tighten in cross-pattern (alternating diagonal screws):
   
   Sequence for 4-screw caps:
   Screw 1 (front-left) → Screw 4 (rear-right)
   Screw 3 (front-right) → Screw 2 (rear-left)
   
   Repeat sequence, gradually increasing torque each cycle

5. Torque to specification:
   - Aluminum rings/scopes: 15-20 in-lb per screw typical
   - Steel rings: 18-25 in-lb per screw typical
   - **Check your specific ring manufacturer specification**
   - **GTGUARD recommendation:** 18 in-lb provides secure mounting without excessive stress

6. Final torque verification:
   - Recheck all screws in same cross-pattern
   - Should reach specified torque without additional turning
   - If screws turn easily, repeat tightening sequence

Critical Warning: Over-torquing cap screws crushes scope tube, damaging internal thermal imaging components. Under-torquing allows scope rotation in rings during recoil. Use calibrated torque wrench.

Step 3.5: Post-Installation Verification

1. Attempt to rotate scope in rings by hand—should not move
2. Check bolt operation (if bolt-action)
3. Cycle action several times
4. Verify no contact between scope and rifle
5. Confirm comfortable cheek weld and eye relief
6. Power on scope, check thermal imaging still functions properly

Digital Zeroing Process: X350L and X650L

Unlike traditional scopes with mechanical turret adjustments, the X350L and X650L use digital reticle positioning—a superior system for thermal imaging:

Advantages of Digital Zeroing

No Mechanical Movement: Reticle adjusts electronically, eliminating mechanical adjustment mechanisms that can fail or lose zero

Unlimited Adjustment Range: Digital reticle moves anywhere on display without physical limitation

Multiple Zero Profiles: Store zeros for different ammunition types, quickly switching between profiles

No Zero Loss: Mechanical turrets lose zero from vibration, impact, or internal wear. Digital systems maintain zero indefinitely

Instant Adjustment: Changes appear immediately on display—no counting clicks or tracking adjustments

Pre-Zero Preparation

Step 1: Gather Required Materials

- Stable shooting rest (benchrest, sandbags, bipod)
- Target stand at 100 yards (recommended zero distance)
- Aiming point (1" orange dots, printed bullseye target)
- Appropriate ammunition (20-30 rounds minimum)
- Notebook for recording data
- Bore sighter (optional but recommended for initial setup)

Step 2: Bore Sight (Optional)

Bore sighting gets you "on paper" at 100 yards, saving ammunition:

1. Remove bolt from rifle (or use chamber laser bore sighter)
2. Secure rifle in rest aimed at 100-yard target
3. Look through bore, center bore view on target
4. Without moving rifle, look through thermal scope
5. Note where reticle aims relative to bore's point of aim
6. Use digital zeroing controls to move reticle toward bore's aiming point
7. Repeat until reticle and bore align on same target point

Alternative: Use laser bore sighter following manufacturer instructions for your caliber.

Zero Procedure: GTGUARD X350L and X650L

Step 3: Access Digital Zeroing Function

1. Power on X350L or X650L
2. Navigate to main menu (typically: long-press MENU button)
3. Select "Zeroing" or "Reticle Adjustment" option
4. Display shows current reticle position and adjustment controls

X350L/X650L Menu Navigation:

• UP/DOWN buttons: Navigate menu options
• LEFT/RIGHT buttons: Adjust values
• MENU button: Enter/Exit menus
• OK/SELECT button: Confirm selections

Step 4: Fire Initial Group

1. Establish stable shooting position
2. Aim reticle center on bullseye through thermal scope
3. Fire 3-round group using consistent technique:
   - Control breathing
   - Steady trigger press
   - Follow through after shot
4. Observe impact points through thermal scope:
   - Heat signature from bullet impacts appears on target
   - May need to wait 5-10 seconds for impact heat to become visible
   - Use spotting scope or walk to target if impacts unclear

Thermal Advantage: Recent bullet impacts show as hot spots on target for several minutes, making group assessment easy even at extended ranges.

Step 5: Calculate Point of Impact

1. Determine group center (average of 3 shots)
2. Measure distance from bullseye to group center:
   - Horizontal displacement (left/right)
   - Vertical displacement (high/low)

Example:
Group center 4 inches low, 2 inches right of bullseye at 100 yards

Step 6: Adjust Digital Reticle

1. Enter zeroing mode in X350L/X650L menu
2. Use directional controls to move reticle:
   - If impacts are LOW, move reticle DOWN (toward impacts)
   - If impacts are HIGH, move reticle UP (toward impacts)
   - If impacts are LEFT, move reticle LEFT (toward impacts)
   - If impacts are RIGHT, move reticle RIGHT (toward impacts)

This seems counter-intuitive but is correct: Move reticle TO the impacts, not away from them

3. Adjustment increments:
   - Typically 0.1 MIL or 0.25 MOA per press
   - Check your scope's adjustment value in specifications

4. Calculate required adjustment:
   Example: 4 inches low at 100 yards
   - 4 inches = 4 MOA at 100 yards
   - Move reticle DOWN 16 clicks (if 0.25 MOA per click)
   - Or move reticle DOWN approximately 1.2 MIL (if 0.1 MIL per click)

Digital Zeroing Principle: You're not adjusting scope mechanism—you're moving the aiming point to match bullet impact. After adjustment, when reticle centers on target, bullet impacts where reticle indicates.

Step 7: Confirm Zero

1. Fire confirmation 3-round group
2. Impacts should be on or very near bullseye
3. If not centered, repeat adjustment process using smaller corrections
4. Once satisfied, fire final 5-round group to verify consistency

Acceptance Criteria:

• All shots within 2-3 inch circle at 100 yards = excellent
• All shots within 4-5 inch circle at 100 yards = acceptable for hunting

Step 8: Save Zero Profile

1. In zeroing menu, select "Save Profile"
2. Name profile for ammunition type:
   - Example: "168gr FGMM" or "55gr Vmax"
3. Confirm save
4. Record zero data in notebook:
   - Date
   - Ammunition details (brand, weight, lot number)
   - Temperature and conditions
   - Zero distance
   - Final group size

X350L/X650L Advantage: Multiple stored profiles allow quick switching between ammunition types without re-zeroing.

Advanced Zeroing Considerations

Multiple Distance Zeros

Some hunters prefer zeros at distances other than 100 yards:

200-Yard Zero:

• Popular for flat-shooting calibers (6.5 Creedmoor, .308 Win)
• Provides point-blank range to ~250 yards typically
• Minimal holdover required for most shots under 300 yards

50-Yard Zero:

• Common for close-range applications (hog hunting in thick cover)
• Matches 200-yard impact for many calibers (ballistic arc)
• Requires significant holdover beyond 250 yards

Procedure Identical: Follow same digital zeroing steps at chosen distance

Managing Multiple Ammunition Profiles

The X350L and X650L store multiple zero profiles:

Profile Management Strategy:

Profile 1: Primary hunting ammunition (most frequently used)
Profile 2: Secondary hunting load (different weight/type)
Profile 3: Practice ammunition (cheaper plinking loads)
Profile 4: Long-range precision loads

Switching Profiles:

1. Access zeroing menu
2. Select "Load Profile"
3. Choose desired ammunition profile
4. Digital reticle immediately adjusts to saved zero

Practical Application: Hunt with Profile 1 (premium hunting ammo). Practice with Profile 3 (cheap ammo) without losing hunting zero. Switch profiles in seconds before hunts.

Temperature and Altitude Effects

While digital zeros don't shift mechanically, bullet trajectory changes with environmental conditions:

Temperature Impact:

• Powder temperature affects muzzle velocity
• Cold weather typically reduces velocity 2-5 fps per 10°F drop
• Hot weather increases velocity similarly
• Impact at 300 yards: Approximately 1-2 inches vertical for 50°F temp swing

Altitude Impact:

• Reduced air density at altitude decreases drag
• Bullets strike higher at altitude than sea level
• Impact at 300 yards: Approximately 2-3 inches higher at 8,000' vs. sea level

Digital Zero Strategy: Establish separate zero profiles for significantly different conditions:

• "Summer Zero" (80-90°F)
• "Winter Zero" (20-40°F)
• "Mountain Zero" (high altitude hunts)

Or learn holdover adjustments from primary zero for various conditions.

Zero Verification and Maintenance

When to Re-Verify Zero

Mandatory Verification:

• After scope removal and reinstallation
• After significant impact or drop
• Before important hunts (annual deer season, expensive guided hunts)
• When switching to new ammunition lot
• After extreme temperature changes (storage in hot vehicle, freezing temperatures)

Recommended Verification:

• Every 200-300 rounds fired
• Quarterly if scope stored on rifle
• After long-term storage

Quick Zero Check Procedure

Don't want to fire full zeroing session? Quick check confirms zero retention:

1. Set up target at your zero distance (typically 100 yards)
2. Fire 3-round group from stable rest
3. Measure group center from bullseye:
   - Within 1-2 inches = zero confirmed good
   - 2-4 inches = minor adjustment may be needed
   - >4 inches = full re-zero required

Zero Retention Issues

If zero shifts frequently, diagnose root cause:

Mounting Problems:

• Ring screws not properly torqued → retorque to specification
• Ring bases loose on Picatinny rail → apply Loctite, retorque
• Picatinny rail loose on receiver → remove rail, clean, Loctite, reinstall

Scope Problems:

• Internal component damage from excessive ring torque → professional inspection required
• Shock damage from impact or drop → warranty service may be necessary

Rifle Problems:

• Action screws loose (bolt-action rifles) → torque to spec
• Barrel contact with stock (accuracy issue) → barrel channel relief or bedding

Ammunition Variables:

• Different ammunition lots have velocity variations → verify zero with each new lot
• Mixed ammunition types in same session → establish separate zeros

Common Mounting Mistakes and Solutions

Mistake #1: Over-Torqued Ring Screws

Symptom: Scope won't rotate in rings even with excessive force; visible compression of scope tube; degraded thermal imaging quality

Cause: Ring cap screws torqued beyond specification, crushing aluminum or magnesium scope tube

Solution:

1. Immediately loosen ring caps
2. Inspect scope tube for permanent deformation
3. If tube shows damage, contact GTGUARD warranty support
4. If no visible damage, remount using correct torque (18 in-lb recommended)

Prevention: Always use calibrated torque wrench. Hand-tightening frequently over-torques.

Mistake #2: Insufficient Ring Spacing

Symptom: Scope rocks forward/back in rings during recoil; inconsistent zero; rapid zero loss

Cause: Rings positioned too close together, insufficient contact area with scope tube

Solution:

1. Remount with rings spaced further apart
2. Ensure both rings positioned on cylindrical tube sections (not tapered areas)
3. Minimum ring spacing: 3.5 inches center-to-center for X350L/X650L

Prevention: Reference X350L/X650L dimensions when positioning rings initially.

Mistake #3: Misaligned Rings

Symptom: Difficulty getting scope into rings; scope binds when tightening caps; erratic zero

Cause: Ring bases not aligned, causing scope tube stress when caps tighten

Solution:

1. Loosen ring bases
2. Use ring alignment tool to check alignment
3. Adjust base positions until alignment bars show <0.003" gap
4. Retorque base screws
5. Install scope without forcing

Prevention: Always check ring alignment before installing expensive thermal scopes.

Mistake #4: Improper Eye Relief

Symptom: Incomplete thermal display view (vignetting); inconsistent cheek weld; scope strikes face during recoil

Cause: Scope mounted too far forward or rearward from optimal 38mm eye relief position

Solution:

1. Loosen ring caps
2. Adjust scope fore/aft position while in shooting stance
3. Optimal position: Full thermal display visible without vignetting at 38mm eye distance
4. Retighten ring caps to specification

Prevention: Mount rifle in actual shooting position, adjust eye relief before final tightening.

Mistake #5: No Loctite on Fasteners

Symptom: Ring screws gradually loosen from recoil vibration; zero loss over time; complete scope detachment (dangerous)

Cause: Thermal expansion/contraction cycles and recoil vibration loosen untreated threads

Solution:

1. Remove all mounting screws
2. Clean threads with isopropyl alcohol
3. Apply 1-2 drops blue Loctite 242 to each screw
4. Reinstall and torque to specification
5. Allow 4-6 hours cure time before shooting

Prevention: Always apply Loctite during initial installation.

Mistake #6: Skipping Ring Alignment Check

Symptom: Scope binds in rings; difficult to adjust reticle level; rapid zero loss; accuracy issues

Cause: Assumed rings align from factory—they often don't

Solution:

1. Remove scope
2. Use ring alignment bars to measure misalignment
3. Adjust ring base positions or use lapping compound to correct (advanced technique)
4. Verify alignment <0.003" before reinstalling scope

Prevention: Always verify ring alignment before mounting expensive thermal scopes. $30 alignment tool protects $2,000+ investment.

Maintenance and Long-Term Care

Periodic Inspection Schedule

Monthly (Active Use):

• Visual inspection of mounting screws
• Check for scope movement in rings
• Verify zero with quick 3-round check

Quarterly:

• Retorque all mounting screws to specification
• Clean scope tube contact areas
• Verify Picatinny rail tightness

Annually:

• Complete scope removal and inspection
• Clean all mounting surfaces thoroughly
• Fresh Loctite application to all screws
• Full re-zero procedure

Scope Removal and Reinstallation

Digital zeros save when removing scopes:

Removal Procedure:

1. Record current zero profile settings (backup)
2. Loosen ring cap screws in reverse cross-pattern
3. Remove caps and lift scope free
4. Clean scope tube with isopropyl alcohol
5. Clean ring contact surfaces
6. Store scope in protective case

Reinstallation:

1. Follow complete mounting procedure (don't shortcut)
2. Torque all fasteners to specification
3. Level reticle carefully
4. Load saved zero profile
5. Fire verification group to confirm zero return

Zero Return Expectation: Properly mounted scopes with quality rings return to zero within 1-2 inches at 100 yards after removal/reinstallation.

Troubleshooting Zero Problems

Problem: Zero Shifts Between Sessions

Possible Causes:

1. Loose mounting screws
2. Ring/base movement on rail
3. Ammunition variations
4. Shooter technique inconsistency

Diagnosis Procedure:

Step 1: Check all mounting screws with torque wrench
Step 2: Attempt to move scope by hand (should not budge)
Step 3: Fire groups with same ammunition lot at controlled temperature
Step 4: Have experienced shooter fire group with same setup

Solution Based on Diagnosis:

• Loose screws → Retorque, apply Loctite if missing
• Scope moves → Remount entire system correctly
• Ammunition → Verify zero with each lot
• Technique → Practice fundamentals, use better rest

Problem: Large Group Sizes Despite Solid Zero

Not a Mounting Issue: Mounting affects zero retention, not group size. Large groups indicate:

Rifle Issues:

• Barrel problems (fouling, damage, improper break-in)
• Action screw torque incorrect
• Bedding issues (stock-to-action contact)
• Trigger problems

Ammunition Issues:

• Low-quality ammunition
• Mixed ammunition lots in same group
• Ammunition/barrel incompatibility

Shooter Issues:

• Poor shooting technique
• Inadequate rest/support
• Flinching, jerking trigger

Scope Issues (Rare):

• Damaged reticle or display
• Internal component malfunction

Solution: Address rifle accuracy fundamentals first; mounting is unlikely cause of poor groups if zero remains consistent.

Problem: Scope Strikes Face During Recoil

Immediate Safety Concern

Causes:

• Insufficient eye relief (scope too close to eye)
• Improper stock fit (comb too low, length of pull incorrect)
• Excessive recoil (magnum calibers with lightweight rifles)

Solutions:

1. Remount scope with correct 38mm eye relief:
   - Measure distance from rear eyepiece lens to eye
   - Should be minimum 38mm (1.5"), preferably 40-45mm for safety margin

2. Add cheek riser to stock if scope requires forward mounting

3. Install recoil pad or limbsaver to reduce felt recoil

4. Reduce ammunition power (lighter loads, reduced recoil loads)

5. Use proper shooting technique:
   - Firm grip pulling rifle into shoulder
   - Cheek weld established before trigger press
   - Follow through preventing head lifting

Prevention: Always verify eye relief with rifle in mounted shooting position before final ring tightening.

Problem: Thermal Image Appears Degraded After Mounting

Symptoms:

• Reduced image clarity compared to pre-mounting
• Unusual artifacts in thermal display
• Inconsistent thermal sensitivity across field of view

Possible Causes:

• Over-torqued ring screws crushing scope tube
• Misaligned rings stressing optical system
• Shock damage during mounting process
• Coincidental internal malfunction unrelated to mounting

Diagnosis:

1. Completely remove scope from rings
2. Power on scope, observe thermal image quality off-rifle
3. Compare to pre-mounting image quality if known
4. Inspect scope tube for compression marks or damage

Solutions:

• If image quality normal off-rifle but degrades in rings → Remount with less torque, verify ring alignment
• If image quality degraded off-rifle → Internal damage, contact GTGUARD warranty support
• If compression marks visible → Permanent damage likely, warranty claim necessary

Prevention: Never exceed recommended ring torque specifications. 18 in-lb adequate for X350L/X650L.

Quick Reference Charts

Torque Specification Quick Reference

Component	Material	Torque Range	Recommended	Notes
Ring Base Screws	Steel rings	55-65 in-lb	60 in-lb	Into steel rail
Ring Base Screws	Aluminum rings	45-55 in-lb	50 in-lb	Into aluminum rail
Ring Cap Screws	All types	15-25 in-lb	18 in-lb	X350L/X650L spec
Rail Mounting Screws	Into receiver	25-35 in-lb	30 in-lb	Verify manufacturer spec
Action Screws	Bolt-action	40-65 in-lb	Varies by rifle	Check manufacturer

Critical Note: Always verify your specific ring manufacturer's specifications. Values above are typical but not universal.

X350L and X650L Mounting Specifications

Specification	X350L	X650L
Tube Diameter	30mm	30mm
Length	190mm	~200mm
Weight	550g (19.4 oz)	~600g (21.2 oz)
Eye Relief	38mm	38mm
Objective Diameter	35mm	50mm
Recommended Ring Height	Medium to High	High to Extra-High
Minimum Ring Spacing	3.5 inches	4.0 inches
Recommended Ring Torque	18 in-lb	18 in-lb

Digital Zeroing Quick Steps

1. Access zeroing menu → MENU button (long press)
2. Select "Zeroing" or "Reticle Adjustment"
3. Fire 3-round group at 100 yards
4. Note impact point relative to aim point
5. Move reticle TO impacts (not away from them):
   - Impacts LOW → Move reticle DOWN
   - Impacts HIGH → Move reticle UP
   - Impacts LEFT → Move reticle LEFT
   - Impacts RIGHT → Move reticle RIGHT
6. Fire confirmation group
7. Save profile with ammunition description
8. Record zero data in log book

Troubleshooting Decision Tree

Problem: Zero Loss

→ Check mounting screws torque
  ├─ Loose? → Retorque with Loctite, re-verify zero
  └─ Tight? → Continue

→ Attempt to move scope by hand
  ├─ Moves? → Remount entire system correctly
  └─ Solid? → Continue

→ Inspect ring/base interface
  ├─ Gaps visible? → Misalignment, remount with alignment check
  └─ Good contact? → Continue

→ Verify rail mounting to receiver
  ├─ Loose? → Remove rail, clean, Loctite, reinstall
  └─ Tight? → Continue

→ Test with known-accurate ammunition
  ├─ Zero shifts with different ammo? → Establish multiple profiles
  └─ Consistent shift all ammo? → Internal scope issue, contact support

Advanced Techniques

Precision Ring Lapping

For ultimate accuracy and zero retention, consider lapping rings (advanced technique):

Purpose: Removes minor manufacturing imperfections, ensures 100% contact between rings and scope tube

Procedure:

1. Assemble rings without scope
2. Apply lapping compound to alignment bars
3. Rotate bars in rings, gradually removing material
4. Clean thoroughly, inspect for even contact
5. Install scope normally

Benefit: Distributes clamping force evenly, potentially improving zero retention

Caution: Improper lapping can damage rings. Consider professional gunsmith service if unfamiliar.

Using Return-to-Zero Mounts

Quick-detach (QD) mounts allow rapid scope removal/reinstallation:

Advantages:

• Tool-free scope removal
• Enables single scope across multiple rifles
• Facilitates storage/transport
• Returns to zero without re-zeroing (when properly installed)

Considerations:

• More expensive than standard rings ($150-$400 vs. $50-$150)
• Added mechanical complexity (more potential failure points)
• Requires high-quality units for reliable zero return (LaRue, Spuhr, ADM brands)

Recommendation for X350L/X650L: Standard rings adequate for most users. QD mounts beneficial only if frequently moving scope between rifles.

Cant and Cosine Error

Scope cant (tilt) causes bullets to impact away from reticle:

Understanding Cant Error:

• 5° cant produces ~1 inch horizontal error at 300 yards with 10 MOA holdover
• 10° cant produces ~4 inches horizontal error at same distance
• Error increases with distance and holdover amount

Anti-Cant Devices:

• Scope-mounted bubble levels ($30-$80)
• Rail-mounted levels ($40-$100)
• Built-in electronic levels (some scopes include)

X350L/X650L Solution:

• Mount scope carefully with reticle perfectly level to receiver
• Consider adding bubble level for precision long-range work
• Digital reticle remains level—rifle cant is the variable to control

Storage and Transportation

Rifle Storage with Mounted Thermal Scope

Short-Term Storage (Days to Weeks):

- Store rifle in climate-controlled environment
- Remove batteries from X350L/X650L (prevent drainage)
- Lens caps on objective and eyepiece
- Avoid direct sunlight (prevents thermal sensor saturation)
- Vertical storage preferred (lessens mounting stress)

Long-Term Storage (Months):

- Consider scope removal if stored >6 months
- If leaving mounted:
  - Verify all mounting screws torqued
  - Apply fresh Loctite if necessary
  - Store in hard case with dessicant packets
  - Temperature-stable location (avoid attics, garages with extreme swings)

Transportation

Vehicle Transport:

- Hard rifle case preferred (protects against impact)
- Avoid leaving in hot vehicles (thermal scopes sensitive to extreme heat)
- Remove from direct sunlight (prevents thermal sensor issues)
- Padded case prevents vibration loosening mounting screws

Air Travel:

- TSA-approved hard case with locks
- Remove batteries (carry separately in carry-on per TSA rules)
- Photograph scope/mounting before travel (documents condition for insurance)
- Consider additional insurance for X350L/X650L value
- Re-verify zero after travel (vibration may shift zero slightly)

Warranty Considerations

GTGUARD X350L and X650L Warranty

Standard Warranty Coverage:

• 2-year manufacturer warranty from purchase date
• Covers manufacturing defects and materials
• Does not cover abuse, neglect, or improper installation

Mounting-Related Warranty Issues:

Covered:

• Internal component failure from normal recoil/use
• Thermal sensor malfunction unrelated to mounting
• Digital zeroing system failure

Not Covered:

• Damage from over-torqued ring screws
• Crushed scope tubes from improper mounting
• Damage from drops or impacts during installation
• Unauthorized modifications to scope

Best Practices to Preserve Warranty:

• Follow all mounting specifications in this guide
• Use calibrated torque wrench (prevents over-torquing claims)
• Document installation with photos (proves proper installation)
• Keep records of ammunition used (eliminates excessive recoil claims)
• Register scope with GTGUARD (establishes purchase date)

Warranty Service Procedure

If scope issues develop:

1. Contact GTGUARD support: service@gtguardhunt.com
2. Provide:
   - Order number or proof of purchase
   - Description of problem
   - Photos of scope showing issue
   - Photos of mounting setup

3. GTGUARD will:
   - Evaluate claim eligibility
   - Provide RMA number if warranty service approved
   - Supply return shipping instructions

4. Ship scope with:
   - RMA number clearly visible on package
   - Original packaging if available (or equivalent protection)
   - Description of problem included in box
   - Contact information for return shipment

Turnaround Time: Typically 2-4 weeks for warranty repair/replacement

Conclusion: Mounting Excellence Ensures Performance

Proper thermal scope mounting isn't optional—it's essential for realizing the full capability of your GTGUARD X350L or X650L investment. The procedures in this guide ensure:

Immediate Benefits:

• Rock-solid mounting that withstands recoil across thousands of rounds
• Precise digital zero that returns consistently after scope removal
• Optimal eye relief providing comfortable, full thermal display view
• Protected warranty coverage through proper installation

Long-Term Advantages:

• Minimized maintenance requirements
• Extended scope service life through correct mounting stress
• Confidence in equipment reliability during critical hunting opportunities
• Maximum resale value from well-maintained equipment

The X350L and X650L's digital zeroing system eliminates the mechanical adjustment complexity of traditional scopes, but proper physical mounting remains critical. Follow the torque specifications, verify ring alignment, establish correct eye relief, and maintain your installation—your thermal scope will deliver decades of reliable performance.

Whether you're installing your first thermal scope or troubleshooting mounting issues with current equipment, this guide provides the technical foundation for professional-grade results. Take the time to do it right initially, and you'll spend more time hunting successfully and less time chasing zero problems at the range.

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Frequently Asked Questions

Q: Can I mount the X350L or X650L using standard 30mm scope rings? A: Yes. Both the X350L and X650L feature standard 30mm tube diameter compatible with any quality 30mm Picatinny rings. Choose appropriate ring height: medium to high for X350L, high to extra-high for X650L depending on rifle type and objective clearance needs.

Q: What torque should I use for ring cap screws on the X350L and X650L? A: GTGUARD recommends 18 inch-pounds for ring cap screws on both models. This provides secure mounting without risking damage to the scope tube. Always use a calibrated torque wrench—hand-tightening frequently over-torques and can crush the scope tube.

Q: Do I need to re-zero my thermal scope after removing and reinstalling it? A: The X350L and X650L's digital zero profiles save in scope memory, so your zero settings remain. However, physical mounting variations mean you should always fire a verification group after reinstallation. Properly mounted scopes typically return within 1-2 inches at 100 yards, requiring only minor digital reticle adjustment if any.

Q: How is digital zeroing different from traditional scope adjustment? A: Traditional scopes mechanically move the reticle by adjusting turrets. Digital thermal scopes like the X350L and X650L electronically reposition the aiming point on the display. Digital zeroing offers advantages: no mechanical parts to fail, unlimited adjustment range, multiple saved zero profiles, and instant adjustment application. The trade-off is dependence on electronics and battery power.

Q: What ring height should I use for my AR-15 with an X650L? A: Extra-high rings (1.50" center height or higher) are recommended for AR-15 platforms with the X650L due to its 50mm objective lens and the need to clear the rail while achieving proper cheek weld. The X350L typically works with high rings (1.26-1.50") on AR platforms due to its smaller 35mm objective.

Q: Can over-torqued ring screws damage my thermal scope? A: Absolutely. Excessive ring torque crushes the scope tube, potentially damaging the internal microbolometer sensor, display components, and structural integrity. The X350L and X650L specify 18 in-lb maximum ring cap torque for this reason. Damage from over-torquing is not covered under warranty. Always use a calibrated torque wrench.

Q: How often should I re-verify my thermal scope's zero? A: Verify zero after scope removal/reinstallation, significant impact or drop, before important hunts, when switching ammunition lots, and after extreme temperature changes. Additionally, fire verification groups every 200-300 rounds or quarterly during active use. Quick 3-round checks confirm zero retention without full re-zeroing sessions.

Q: Why does my scope shift in the rings during recoil? A: Scope movement in rings indicates: insufficient ring cap torque (under-torqued), missing or ineffective Loctite on screws, insufficient ring spacing (rings too close together), misaligned rings causing uneven pressure, or extremely heavy recoil exceeding ring capability. Address by verifying proper torque, applying Loctite, ensuring adequate ring spacing (3.5"+ for X350L/X650L), and checking ring alignment.

Q: Should I lap my scope rings before installing the X350L or X650L? A: Ring lapping is optional, not required. Quality modern rings typically provide adequate contact without lapping. Lapping benefits: ensures 100% ring-to-scope contact, potentially improves zero retention, distributes clamping force evenly. However, improper lapping can damage rings. Unless you're experienced or have access to proper tools, standard installation without lapping works excellently for the X350L and X650L.

Q: Can I use Weaver-style rings for my thermal scope? A: We recommend Picatinny-spec rings for the X350L and X650L. Weaver rings may physically fit but lack the positive cross-bolt engagement of Picatinny systems, relying solely on friction. For expensive thermal scopes requiring reliable, repeatable mounting, Picatinny rings provide superior security and zero retention.

Q: What's the proper eye relief for the X350L and X650L? A: Both models specify 38mm (approximately 1.5 inches) eye relief. This distance provides full thermal display view without vignetting. In practice, position the scope so your eye naturally aligns 38-45mm from the rear eyepiece lens when in your normal shooting stance. Insufficient eye relief causes display vignetting; excessive eye relief risks scope striking your face during recoil.