The AR15A4 Plunger Spring 160302041 is a genuine Colt® forward assist plunger spring, engineered to keep your AR-15/M16-pattern rifle running smoothly and reliably. Designed as a factory replacement part for the Colt AR15A4, this small but critical spring provides the proper tension on the forward assist plunger, ensuring positive engagement when you need to drive the bolt fully into battery.
If you’re maintaining a duty rifle, refreshing a hard-use carbine, or completing a correct Colt build, the AR15A4 Plunger Spring (Brownells #160302041) delivers OEM fit, function, and long-term durability.
Factory Colt Forward Assist / Plunger Spring
Colt lists this part as a “Plunger Spring” for Colt AR15A4 rifles, and Brownells explicitly categorizes it under rifle receivers and forward assist parts.
That means you’re getting:
True Colt OEM quality – the same style spring used in factory AR15A4 rifles
Correct spring rate and length for the forward assist plunger system
A drop-in replacement that restores proper tension and feel to your forward assist
Forward assist springs can weaken over time from use, dirt, and metal fatigue. Swapping in a fresh Colt plunger spring helps ensure the forward assist still does its job when your bolt needs a final nudge into lockup.
Built from High-Quality Steel for Reliability
According to Colt-focused retailers, the AR15A4 plunger spring is manufactured from high-grade steel for strength and durability.
Benefits of the steel construction include:
Excellent resilience under repeated compression and cycling
Resistance to wear and deformation even after thousands of uses
Reliable performance in high-round-count training, duty, or defensive rifles
This is a tiny part in terms of size, but it has an outsized effect on the function of your forward assist, especially on rifles that see real use in harsh conditions.
Wide AR-15 / M16 Platform Compatibility
Even though it’s sold as the Colt AR15A4 Plunger Spring, listings show it as compatible with multiple AR-15 variants, including AR-15, M16, and AR-15/M4-type rifles.
Common fitment includes:
Colt AR15A4 rifles (forward assist plunger spring)
Colt AR-15 / M16 / AR-15/M4 platforms using standard forward assist assemblies
Various Colt Match Target and Government Carbine models that share the same plunger/forward assist setup
If your rifle uses a standard Colt-pattern forward assist, this spring is designed to drop in and work with OEM and most mil-spec receivers.
Restore Positive Forward Assist Function
A tired or damaged plunger spring can make your forward assist feel:
Replacing it with the AR15A4 Plunger Spring 160302041 helps bring back:
Positive, crisp forward assist strokes
Fast plunger return and reliable engagement with the carrier
Confidence that, if you do need to use the forward assist, it will work correctly
For rifles used in law enforcement, defensive roles, or serious training, keeping the forward assist system in top condition is simply good insurance.
Perfect for Builds, Repairs & Preventive Maintenance
This Colt plunger spring is an inexpensive part that fits into several important use cases:
New builds:
Finish a Colt-correct or mil-spec upper with a genuine Colt forward assist spring rather than a no-name component.
Repairs:
Fix issues with a weak, sluggish, or non-responsive forward assist by replacing the worn plunger spring.
Preventive maintenance:
Springs are consumable parts. Replacing them at sensible intervals keeps your rifle closer to factory-new reliability.
Spare parts kits:
A small, lightweight spring that’s ideal to keep in an armorer’s kit, range bag, or deployment spare-parts roll.
Given the low cost and high value, many armorers keep several AR15A4 plunger springs on hand for servicing Colt and Colt-pattern rifles.
Easy Drop-In Installation
The AR15A4 plunger spring is designed for straightforward installation as part of the forward assist assembly:
Fits standard forward assist assemblies in AR-15/M16 upper receivers
Installs with the forward assist plunger and roll pin (not included)
No permanent modifications required – simply replace the old spring and reassemble
If you’re comfortable field-stripping AR upper receivers, replacing the plunger spring is a quick job. For duty or defensive rifles, many shooters still prefer to have a qualified armorer verify function after installation.
Technical Specifications – AR15A4 Plunger Spring 160302041
Based on Colt and major distributor listings:
Product Name: AR15A4 Plunger Spring / Plunger Spring for Colt AR15A4
Manufacturer: Colt’s Manufacturing Company
Brownells / SKU: 160302041
Manufacturer ID: Commonly referenced as SP62271 by parts houses
Platform Fit:
Part Type: Forward assist plunger spring
Material: Steel
Quantity: Sold individually
Why Choose the Colt AR15A4 Plunger Spring (160302041)?
If you’re serious about keeping your AR-15 or Colt AR15A4 running at peak reliability, the AR15A4 Plunger Spring 160302041 is an easy upgrade and an essential maintenance item:
Genuine Colt OEM part – correct spec, correct tension, proven reliability
Compatible with AR-15, M16, and AR-15/M4 Colt-pattern rifles
High-quality steel construction built to handle real-world use
Simple, low-cost way to restore positive forward assist function and keep your rifle ready for anything
For armorers, builders, and shooters who prefer real Colt parts over generic substitutes, the AR15A4 Plunger Spring 160302041 is the obvious choice to support long-term performance and reliability.
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