Hello fellow gun enthusiasts,

I have an M5 build that I absolutely love, and I’ve been steadily upgrading it. I have it mostly where I want it, but I want to swap out the Aero Precision bolt catch for a FCD catch that I’ve already purchased.

I tried to remove the screw that holds the bolt catch, but it’s not moving and the hex head is stripping. Unfortunately, the way it’s designed, it screws into a blind hole, so it can’t be driven out from the other side.

The Aero catch works fine, but I want the better made FCD part in there for durability. Does anyone have any experience with getting the screw out?

I’m fine with drilling it out and using a new screw or better yet, a pin. But the hole is so close to the side of the receiver, I’m not sure how to access it.

Try a long T-6 torx driver, which is slightly larger than the 1/16 hex. You may have to sacrifice this wrench/bit. Tap it into the hex head and see if it will turn. Use heat as well. Aero is supposed to use red Loctite on these.

The threads are on the entrance side, so if you try drilling out the stainless pin, you will likely destroy the lower.

Funny thing, I actually tried driving a torx driver in there and it broke off inside the screw head . Now the torx bit piece is stuck in there. I will try to dig it out.

I’m the one who assembled the lower and (regrettably), I used blue thread locker. It’s the same stuff I use on scope rings and mlok accessories, and it’s usually pretty easy to remove.

I may look for a tiny ez out and use some heat, if I can get the chunk of torx bit out of there.

Good luck. For all the "convenience" of the threaded pins, they have a major flaw which you have discovered. Spring pins on an AR-15 lower can be pushed out from either side in a pinch.

I've seen lots of people not realize they need to use the threaded pin in this location and use a spring pin. That's where it really gets interesting.

Sometimes if you tap the broken bit counter clockwise with a 1/16th or thinner punch, you can get the teeth in the torx bit to "let go" and then tap the opposite end to let inertia knock it out.

Honestly though, you may want to try the following while the broken bit is still in there: heat the part to remove the loctite and then tap the broken bit counter clockwise to see if you can get the entire screw to start rotating.  Once it starts moving, you keep tapping it all the way around until it threads out.  I've had to do this several times as a last resort before drilling and it's worked more than once.  It may also be easier with the broken bit still in place as those small allen heads don't give you much surface to seat your punch against.

Yikes!

Ok, first of all, should’ve heated the screw in the beginning, it would come out no problem.

Secondly, to heat the screw use a soldering pen, just hold it on the screw for about 20 seconds, and it will unscrew no problem.

Finally, use pink loctite on optics and these threaded lower screws.  Most people don’t even know it exist.  It’s what you should use.  It’s Loctite 222.

I build on a lot of these lowers.  Once in a while a lower screw will back with 222 after 100’s or 1000’s of rounds, so I use the blue 242, but regardless of which one I use, always heat with soldering pen first before removing.

If for some reason it doesn’t come loose after the first heating, repeat for 10 seconds then try again, rinse and repeat.  I’ve only had that happen once.

As already stated, heat would have made short work of that loctite.

I rarely use loctite unless it’s a bigger screw.  I use Vibra-Tite.  It does no work like a hardened glue, it stays pliable but keeps the screw from backing out.  Something like a Wera Hex Plus key will typically not strip out the fastener like a traditional hex key will.  I have multiple sets and they really do work like they are supposed to.

I left Vibra-tite out of my post, but Vibra-tite VC-3 is fantastic for smaller screws.  Massive thumbs up for it.

Vibra-tite also makes a fantastic product called Drive Grip, helps prevent stripping screws by increasing the grip on your bit & the screw.  Check it out.

I had this exact problem with mine as well. The head stripped when I was trying to swap in a Phase 5 bolt release. I purchased a cheap ez-out kit from amazon with small extractors and put it on an extension. Worked like a charm.