The Timney Skeletonized 661S is a single-stage drop-in trigger for small-pin (.154 in) AR-15 and M4 pattern lower receivers.
A trigger that looks as sharp as it breaks — the skeletonized 661S cuts weight and adds presence without touching reliability.
The Timney Skeletonized 661S drops a 3 lb single-stage pull into small-pin (.154 in) AR-15 lowers through a distinctive skeletonized shoe — machined-out styling that trims mass and gives a build genuine bench presence. Behind the looks sits standard Timney discipline: a hand-calibrated break with no creep, minimal overtravel and a positive reset, delivered in a self-contained drop-in module.
Three pounds is the versatile sweet spot — light enough for precise deliberate work, sensible enough for practical shooting — making the 661S as functional as it is photogenic.
How It Compares
Also compare the Timney Competition 668S Single-Stage Trigger 4 lb for AR-15 Small Pin, Timney 667S-ST Single-Stage Trigger for AR-15 Small Pin and Timney 667S Single-Stage Trigger for AR-15 Small Pin. Browse all triggers and the full Timney Triggers range. New to this? Read our guide: AR-15 Trigger Buyer's Guide.
Ideal For
- Small-pin (.154 in) AR-15 and M4 lower receivers
- Builds that want a distinctive skeletonized shoe with reduced mass
- Shooters who want a versatile 3 lb single-stage break
- A self-contained drop-in module that installs in minutes
Key Features
- 3 lb hand-calibrated break — the versatile match weight
- Skeletonized shoe — distinctive style, reduced mass
- Self-contained drop-in module — minutes to install
- Small-pin (.154 in) fit — standard Mil-Spec lowers
Compatibility & Fitment
Drops into small-pin AR-15/M4 pattern lower receivers with .154 in trigger pins, via the existing pin holes. Large-pin receivers are not compatible, so confirm your pin size before ordering. Function-check the rifle before live fire.
Technical Specifications
Platform | AR-15 / M4 |
Fits | Small-pin (.154 in) AR-15 / M4 lower receivers |
Type | Single-stage drop-in trigger, skeletonized shoe |
Pull Weight | 3 lb |
Made in | USA |
Brand | Timney Triggers |
US Shipping & Support
Shipped from D&R Sports Center in the USA with fast, tracked delivery. Questions on fit, mounting or which model suits your setup? Our team is glad to help before and after your purchase.
Frequently Asked Questions
Does the 661S fit small-pin AR lowers only?
Yes, this version is cut for AR-15 and M4 pattern receivers using small .154 in trigger pins. That is the standard mil-spec dimension, but some receivers use large pins and those will not take it. Confirm the pin size on your lower before you order.
What is the point of the skeletonized shoe?
The shoe is cut away rather than solid, which changes both the weight of the moving part and the way your finger registers on the face. Some shooters find the open shape gives a clearer sense of exactly where they are contacting the trigger. It is a distinctive look as well, which is part of the appeal on a build where the internals are on show.
How heavy is the break?
It is a single-stage unit set at 3 lb, which is a practical weight for general shooting rather than a dedicated light match pull. There is no take-up stage to hold against; you press once and the shot breaks. If you want something you can dial up or down, an adjustable trigger is the better route.
How does it compare to Timney's plainer drop-ins?
Mechanically it sits alongside units like the 667S curved-shoe drop-in, so the main differences are shoe shape and pull weight rather than a different way of working. Both are small-pin drop-ins that fit the same way and need the same tools.
