Replacement Spring Set for the FRT-15L3™
Pros & cons
What works
- Exact OEM specification - 0.025 inch wire diameter identical to factory springs
- 17-7 PH stainless steel construction - maintains spring rate across 10,000 cycles
- 14.2 gram total weight - 2.3 grams lighter than aftermarket spring kits
- 5.5 lb consistent pull weight - ±0.1 lb variation across temperature range
Trade-offs
- No installation tools included - requires separate $22.50 armorers wrench purchase
- Packaging lacks humidity control - springs may develop surface oxidation in >80% RH environments
- Disconnector spring requires specific orientation - incorrect installation causes 0.5 second reset delay
- Not compatible with reduced-power modifications - will not function with aftermarket lightened hammers
Video review
Expert review
Specs at a glance
About this product
What is the Replacement Spring Set for the FRT-15L3™? It is a precision-engineered three-spring assembly designed specifically for maintaining optimal forced reset trigger timing in the FRT-15L3 system. This set contains factory-spec replacement components that restore original trigger pull weight and reset characteristics when installed according to the FRT-15 Installation & Timing Protocol.
What is the Replacement Spring Set for the FRT-15L3™ used for?
This spring set restores original forced reset trigger performance when factory springs exhibit fatigue or deformation. The hammer spring maintains 5.5 lb trigger pull weight, the trigger spring ensures 0.08-second reset timing, and the disconnector spring prevents hammer follow. All springs are manufactured from 17-7 PH stainless steel with identical specs to original equipment.
How does the Replacement Spring Set for the FRT-15L3™ compare to McMaster-Carr spring #9657K611?
The FRT Triggers set provides exact geometric and force curve matching where the McMaster-Carr alternative requires manual modification. Our hammer spring delivers consistent 5.5 lb pull weight across 10,000 cycles while the generic spring varies ±0.8 lb after installation. The FRT set includes proper disconnector spring geometry that the McMaster solution lacks entirely.
What does it weigh and what are the dimensions?
Total set weight is 14.2 grams with individual springs measuring: hammer spring 12.7mm length × 6.35mm OD, trigger spring 9.5mm length × 4.76mm OD, disconnector spring 7.9mm length × 3.18mm OD. Packaging adds 2.3 grams in a 75mm × 50mm × 10mm blister pack. Spring wire diameters are identical to OEM at 0.025 inches for all components.
Who is this NOT for?
This set is not compatible with standard mil-spec AR-15 triggers or binary trigger systems. Users seeking reduced pull weight should consider the more on Freedom Finger Triggers reduced-power spring kit instead. The springs will not function properly in lowers exceeding 0.005 inches out-of-spec per the AR-15 Lower Receiver Machining Tolerance guide — our editorial take.
What's in the box?
Package contains exactly three springs: one hammer spring (p/n SPR-HAM-FRT15L3), one trigger spring (p/n SPR-TRG-FRT15L3), and one disconnector spring (p/n SPR-DISC-FRT15L3). No installation tools or instructions are included—users must reference the FRT-15 Installation & Timing Protocol available separately. Total component count: 3 springs, 0 tools, 0 documentation sheets.
Is the Replacement Spring Set for the FRT-15L3™ worth it at $15?
At $15, this set provides exact OEM replacement without requiring custom spring sourcing or modification time. Compared to purchasing individual springs from specialty suppliers at $6-8 each plus shipping, the set saves approximately $9-12 and ensures proper interaction between components. The cost represents 0.3% of the total FRT-15L3 system value while restoring 100% of original performance.
Key attributes
| Compatibility | FRT-15L3 Trigger System Only |
| Material | 17-7 PH Stainless Steel |
| Spring Count | 3 springs |
| Wire Diameter | 0.025 inches |
| Pull Weight | 5.5 lb |
| Reset Timing | 0.08 seconds |
| Package Weight | 14.2 grams |
| Package Dimensions | 75mm × 50mm × 10mm |
What's in the box
- 1 x Hammer Spring
- 1 x Trigger Spring
- 1 x Disconnector Spring
Frequently asked questions
- Is it compatible with Gen 3 PMAGs?
- Spring compatibility relates to trigger mechanism function only, not magazine interface. The FRT-15L3 trigger system functions with all MIL-STD-1913 pattern magazines including Gen 3 PMAGs. Magazine selection does not affect spring performance or replacement interval.
- Does it fit Anderson Manufacturing lowers?
- Compatibility depends on lower receiver machining tolerance, not manufacturer branding. Lowers must maintain 0.005 inches maximum deviation from MIL-SPEC dimensions as detailed in our [AR-15 Lower Receiver Machining Tolerance guide](/blog/ar-15-lower-receiver-machining-tolerance-frt-drop-in/). Anderson Manufacturing produces receivers within these specifications when properly machined.
- How long does shipping take?
- Standard shipping processing time is 2 business days with USPS Priority Mail delivery in 3-5 additional days. Expedited options include UPS 2-Day Air at $18.50 additional cost. International shipments require 10-15 business days and subject to local customs clearance delays.
- Can I return it if it doesn't fit?
- Returns accepted within 30 days for unopened packaging only. Installed springs cannot be returned due to function testing and potential deformation. Customers must verify lower receiver compatibility using our tolerance guide before purchase. Return shipping cost: $7.50 deducted from refund amount.
- Does this work with Geissele Maritime Bolt Catch?
- Spring function is independent of bolt catch mechanism. The [Geissele Maritime Bolt Catch](/blog/frt-binary-trigger-geissele-maritime-bolt-catch-compatibility/) operates separately from trigger springs. Our technical analysis confirms no interaction between spring set and bolt catch components when both are properly installed.