Bolt catch broke at round #71. Any advice would be appreciated.
Spike’s H buffer and spacer
RRA lower
DD LPK
Spike’s magwell block
Colt factory upper and bolt(ramped by ADCO)
KNS pins
I run a Slash 9Q buffer and Wolff xtra power spring and have never broken a bolt catch .
First question, did you (at any time) drop the hammer while the upper and lower were seperated (dry fire)?
Also, you are need to be using a 9mm buffer (not an H buffer).
C4
Yes, my son assembled the lower. He dropped the hammer once before I told him not to. Do you think this could be the cause?
He more than likely cracked it.
C4
I hope this turns out to be the case. Thank You.
You are welcome.
C4
Stag Arms bolt catch broke on my 9mm AR…
Figure probably 2500 - rounds through it…
Replaced it and swapped 9mm Buffer from heavy buffers…about 3000 rounds through no problem.
My set up is
RRA 9mm 10.5 Upper
Ramped RRA Bolt
Hahn Block
Stag Hammer
We ordered a new bolt catch and a 9mm buffer. All of the advice is appreciated.
My son is 15 years old and this is the first AR that he assembled himself. We are both attending Sully’s armorer course in a couple of weeks and he is pumped.
Good that your ordering a 9mm buffer. It’s not the weight that’s causing your bolt to break, but rather the length your Buffer, allowing your BCG to travel too far back. Standard AR buffers are too short for 9mm and when shot, the BCG flys back for what is normal for an 223 round and then slides forward, impacting the bolt catch. Solution is to get a longer 9mm buffer, or get a spacer that prevents the buffer to fly it’s full length back. Spikes makes this spacer so you can get one from them. My buddy says to add quarter to the bottom of the buffer tube. Not sure if it would work, but the concept is sound. I’m going to lathe one for my 9mm AR because like you I learned the hard way and broke my bolt catch. 
Here’s my broken catch. It broke at about 40 rounds.
