I know I saw a post about this probably over a year ago.  Why does this happen and does anybody make a better/stronger bolt catch.  It almost looked like pot metal the way it cracked.

I am running a  DDLES colt style lower with an 8.5" CMMG complete upper and the buffer is a spikes ST-9 made for a 9mm AR and a extra power wolff spring.

Thanks!

Here is a post I created a few weeks ago.  I think I damaged my bolt catch when I used a carbine buffer and spring right after the build.....was pretty excited to try out the build and I didn't pay close enough attention to the various buffer sizes/weights:  http://www.ar15.com/forums/t_3_15/664720_JP_9mm_Silent_Spring_and_Broken_Bolt_Catch.html

 

I used quarter in my buffer tube as well.

The buffer I have is the Sikes ST-9x....This is the longer heavier buffer already.

Does anyone make a stronger aluminum or titanium bolt catch?

Have you checked to see how far past the bolt catch the bolt face is going? If it's going to far it will build up the speed and break it. You may have to add some quarters.

I just checked my JP 9mm Silent Spring...the bolt stops at about 0.138" past the bolt catch.  This is with me pulling on the charging handle all the way to the back till it stops.

How would you know how far back its going when its fired?

Easy and most shootable solution: disable the bolt-hold-open-on-empty feature. Let the bolt close on an empty chamber. Just use the BHO manually. That is how my AR15/9 is set up (with a Hahn mag block) and it works great.

The CMMG catch I had was taller than the RRA I am running now. Don't know if this has anything to do with it but thought I would share. I'm curious also as to the gap in bolt face to bolt catch with charging handle pulled rearward. Over travel was my first thought.

it is a CMMG lower parts kit

But I am still not sure what it matters with the bolt pulled back with the charging handle means.  Doesn't the travel or over-travel of the bolt depend on how much buffer and spring there is to absorb it?

I us a Heavy Buffers 45 buffer & Wolf extra power spring with my 9MM & 40 S&W uppers & have never broken a bolt catch.

 














 

This was the first time it broke but only 100-150rd in.   I will replace it and see if it was just a fluke.  Thanks for the info.

I agree that its most likely a fluke (I hope for all of us QC10 guys).  Just for your info, I have a QC10 CLT9MM lower that I've run over 500 rounds through (I know its not a lot, but its pretty new).  I used an RRA LPK (standard Mil-Spec parts), a Slash 9Q-T buffer and both a Wolff XP spring and a standard carbine spring.  I am shooting unsuppressed (suppressor still in jail) and found that the rifle would not cycle with the full 9Q-T weight and XP spring.  Keeping the full buffer weight with a standard buffer spring fixed this.  Making the buffer lighter (going to the 9Q weight instead of the full 9Q-T weight) with the XP spring also fixed the issue.  I elected to stay with the full 9Q-T buffer weight and have a standard carbine buffer spring in it now.  No issues at all.  It was the worst shooting Remington UMC 147gr ammo, but with the current setup, that ammo cycles fine.  I have not had any issues with the bolt catch (knock on wood).  Last round hold open works every time now with the buffer/spring setup I have now.

I don't have a way to measure how much space is between the bolt face and catch when I pull the charging handle all the way back, but when I do that, manually holding the bolt catch, the bolt doesn't lock back until I'm at the very end of the charging handle travel.  I'm sure there is a little space there, but its sure hard to tell how much.  It has to be a very small amount.  If you can perceive additional travel of your charging handle after the bolt locks back, you might try that trick of putting a quarter in the buffer tube.  If I do that, I cannot get the bolt to lock back at the absolute end of the charging handle travel.

It's enough to get a soda when you're strapped at the range.