AR-15 Firing Pin Return Spring- Installation Guide
What the Firing Pin Return Spring Actually Does
The firing pin return spring is one of those small parts that gets ignored until something goes wrong. In your AR-15, this spring pushes the firing pin forward when you release the hammer and pulls it back after the strike. Without it working properly, you get misfires, light strikes, or the pin hangs up in the bolt carrier entirely.
Most factory AR-15 firing pin return springs are decent but not exceptional. They use standard tension that works fine for range days but can cause issues with certain ammunition or in competition scenarios. After thousands of rounds, these springs lose their tension and become inconsistent.
Signs You Need to Replace It
Don't wait for complete failure. Watch for these problems:
- Light strikes on primer, especially with mil-spec ammo
- Intermittent firing or "skipping" during rapid fire
- Firing pin not fully retracting after shot
- Visible wear or deformation on the spring coils
- Your rifle is approaching 5,000+ rounds without spring replacement
Tools You'll Need
Don't overcomplicate this. Here's what actually matters:
- Punch set - 1/16" and 3/32" roll pin punches
- Small gunsmithing hammer or brass hammer
- Cleaning rod or firing pin retaining pin tool
- Vice with soft jaws - protects your receiver
- Magnifying loupe - inspect the firing pin while you're in there
- AR-15 armorer's wrench - makes BCG handling easier
- Clean workspace - tiny parts go missing fast
Firing Pin Return Spring Options Compared
| Spring Type | Weight | Best For | Durability |
|---|---|---|---|
| Factory Mil-Spec | Standard tension | General use, reliability | 5,000-8,000 rounds |
| Reduced Power | 30-40% lighter | Competition, light strikes | 3,000-5,000 rounds |
| Heavy Duty / Enhanced | 20-30% heavier | Hard primers, cold weather | 8,000-12,000 rounds |
| Captured Spring Assembly | Varies | Easy installation, consistency | 7,000-10,000 rounds |
Installation Guide
Step 1: Remove the BCG
Lock the bolt back, push out the two pins, and pull the charging handle and BCG out the rear. Set the charging handle aside. Don't lose those roll pins—they're small and like to disappear.
Step 2: Field Strip the Bolt Carrier Group
Push the firing pin retaining pin out from the side of the bolt carrier. The firing pin slides out the back. You'll see the firing pin return spring wrapped around the firing pin inside the carrier. This is what you're replacing.
Step 3: Remove the Old Spring
Slide the old spring off the firing pin. On some configurations, the spring is captured in a cup—don't force it. Inspect the firing pin while you're at it. Look for:
- Cracks or chips on the striking face
- Bent shaft
- Excessive wear marks
If the firing pin itself is damaged, replacing the spring won't fix your problems.
Step 4: Install the New Spring
Slide the new spring onto the firing pin in the same orientation as the old one. Most springs are directional—they only go on one way. The tighter coils typically face toward the rear of the firing pin. Check your manufacturer's instructions if you're unsure.
For captured assemblies, simply drop the unit into the bolt carrier. No orientation guesswork.
Step 5: Reassemble
Push the firing pin back into the carrier until the retaining pin holes align. Insert the retaining pin from the opposite side you removed it. It should snap into place with minimal force. If it fights you, something's misaligned—stop and check it.
Step 6: Function Check
Cycle the BCG several times by hand. The firing pin should move freely forward and snap back. It shouldn't stick or drag. Dry fire a few times to confirm the spring is seating properly.
Common Mistakes That Ruin the Job
- Forcing the retaining pin - this peens the metal and makes future removal a nightmare
- Wrong spring orientation - reversed springs cause light strikes
- Skipping inspection - always check the firing pin while you're in there
- Over-oiling - excess oil in the firing pin channel collects carbon and gums up
- Not verifying pin retention - a loose retaining pin will walk out during firing
When to Upgrade vs. Replace
For a stock rifle shooting factory ammo, factory-spec springs work fine. Replace them every 5,000-8,000 rounds and you're good. Save your money.
If you're running suppressed, shooting competition, or having light strike issues with specific ammo, the upgrade is worth it. Reduced power springs reduce lock time and trigger pull slightly. Heavy-duty springs solve cold weather reliability and hard primer issues.
Captured assemblies cost more but eliminate the spring-falling-off-during-installation frustration. For beginners, this is the smart choice.
Maintenance Interval
Check the spring every 2,500-3,000 rounds. Look for visible deformation, inconsistent return speed, or any binding. Replace before it fails completely—misfires at the wrong time are embarrassing and dangerous.
Keep spare springs in your range bag. They're cheap insurance against being stranded with a non-firing rifle.