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Guide · updated 2026-08-16

FRT Buffer Weight & Bolt Carrier Guide

The single most common reason an FRT won't run right is the bolt carrier and buffer. Here's how to set it up.

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The RBT Editorial Desk · Firearms parts research & buyer education
AR-15 & HK-platform trigger research · fitment and compliance focus

An FRT depends on the rifle's cycling to reset the trigger. If the timing is off, the trigger won't reset reliably. Two parts drive that timing: the bolt carrier and the buffer.

Use a full-auto / M16-profile bolt carrier

A full-auto (M16-profile) bolt carrier has more mass and the correct profile to work with the FRT's reset. A lightweight or semi-only carrier is a common cause of failure-to-reset. This carrier is legal to own — it does not make a rifle a machine gun by itself.

Choose an H2 or H3 buffer

A heavier carbine buffer (H2 or H3) slows and smooths the cycle, which helps the trigger reset consistently. Many shooters find an H2 or H3 is the difference between an FRT that runs and one that stutters. Pair it with a quality carbine spring.

PartRecommendation
Bolt carrierFull-auto / M16-profile
BufferH2 or H3 carbine
AmmoStandard-pressure 5.56 / .223; avoid weak underpowered loads

If your FRT-15L3 won't reset, check the carrier and buffer first — it's the fix most of the time. See also our installation guide.

This page is general information, not legal advice. Firearm law changes and varies by jurisdiction. Confirm the current law where you live before ordering, and consult a qualified attorney if you are unsure.

Shop these models:
FRT-15L3

Frequently asked questions

What buffer do I need for an FRT?
An H2 or H3 carbine buffer is recommended for reliable reset, paired with a full-auto/M16 bolt carrier.
Do I need an M16 bolt carrier for an FRT?
A full-auto/M16-profile carrier is strongly recommended; a lightweight or semi-only carrier is a common cause of failure to reset. The carrier itself is legal to own.
Is a full-auto bolt carrier legal?
Yes. A full-auto-profile bolt carrier does not by itself make a rifle a machine gun; it is a legal AR-15 part.