I was experiencing light primer strikes with one of my AR-15s. This particular lower has about 4,000 rounds through it. I suspected that the problem lie within the rifle, not the ammo, for two reasons: First, the ammo used to work fine in this rifle; second, the ammo continued to work fine in other rifles. I started with a good cleaning, paying particular attention to the firing pin. I noted that the firing pin looked a little deformed at the collar.
At the next range session, the problem persisted. Therefore, I decided to replace the hammer spring and firing pin. Here is the process:
1. I drove out the hammer spring.
2. The old hammer spring (on the left) has definitely seen some use.
3. Be sure to install the new hammer spring just like the old one.
The legs of the spring have to sit ON TOP of the trigger pin.
4. It’s tough to see in the picture, but the new firing pin (on top) is a tiny bit longer than the old one.
By dry-firing, I can tell that the sound of the falling hammer is a little more forceful.
I’ll update this blog post when I have had a chance to confirm that the problem is gone.