Sheared Off Bolt Catch

[happy_gunner]

Well, this is a first for me.

I just recently finished a 308 AR build, and it turned out great. Shooting some Federal Gold Medal Match then some middle of the road reloads, it was shooting quarter size groups at a 100" yards. Ran factory ammo great, had some ejection issues with the reloads but they were quickly thrown together. That is until my second range trip, third magazine in, when the bolt decided to shear off the bolt catch.

2018-03-25 16.27.16.jpg

2018-03-17 16.36.44.jpg

This was a first for me. After doing a quick search of the interwebs when I got home, I saw that there is much debate about this in the pistol and large caliber AR world. Some say it happens, others say if everything is set up correctly, it should never. Thinking back on it, I do believe I got this part from our odd-and-in part bin when I assemblies it and wouldn't be surprised if it came from a budget lower parts kit, for what it is work. I ended up ordering a DPMS 308 bolt catch, which is made from spring steel.

Anyone else run into this? Thoughts are welcomed and I hope this helps someone avoid my mistake.

[10x25mm]

Surface texture of your bolt catch and the fracture topography suggest it was metal injection molded. MIM can be really good, or really bad.

[JDG]

Pistol calibers are blowback designs, and use a very heavy buffer. The added weight is hard on the bolt catch. If your using a heavy buffer, I'm sure it could cause it.

[hunterspirit]

Pistol buffers should be longer than a carbine buffer therefore limiting the distance allowed to build up energy slamming home.

The bolt carrier should travel just far enough back to eject the spent case. That reduces the chance of shearing the bolt catch. Some folks shim the buffer from behind with quarters .
7 quarters seems to be around right for a heavy carbine buffer.