Im building my first upper. I purchased a Troy industries low profile gas block. It has two set screws on the bottom. My barrel came with one shallow dimple for a set screw. I cut that a little deeper and wider and added a second dimple in the barrel. I used Permatex high temp thread locking compound. Once that set I staked both set screws to ensure no movement.
Today I went to mount the barrel into the receiver and quickly figured out I should have put the barrel nut on before mounting the gas block.
Because of the staked set screws I could not even insert the hex wrench at first. I tapped the inside edge of the set screw a couple times with a punch. Enough to get the hex wrench to squeeze in. I turned on it and the wrench stripped out.
The thread lock is rated to 450 degrees but the directions state 600 degrees is needed to remove the bond. After searching all through the house I couldn’t find my propane torch. The only thing I could find was a damn lighter so I used that for a good 5 minutes then tried to remove the screw. The shaft of my hex wrench twisted about 90 degrees but the screw didn’t even budge. That thing is in there.
I went to price a new propane torch and they are $25-$35 which is almost the cost of the gas block.
I started to drill out the screw in an attempt to salvage the gas block. The bit wore out so I decided to take a break. I doubt I will have much luck drilling out the screw so it looks like I will have to use a dremel and a cutting wheel to take it off:mad:
The good news is I found a local AR specialty gunshop in my area that carries gas blocks. Live and learn.
I’ve had to do this many more times that I’d like to admit. Get some good drill bits and remove the set screws while drilling at low RPMs. It’s not that bad with the right bits. Use cutting oil (or even motor oil) to reduce the heat.
Some of the machine supply houses stock some limited size left hand drill bits. Fastenal and McMaster-Carr may even have some…Left hand twist bits are a good choice because very often as you drill the left hand twist will back the infernal screw out instead of continuing to drive it in. Mayhaps an easy out will do it. Again a left hand twist product as is my favorite handgun…the 1911.
Ended up having to cut it off. Even that wasn’t easy. Luckily a great AR specialty gunshop just south of Portland opened up recently call Curt’s discount gun supply. He had several of the Troy low profile gas blocks in stock which is what I had to cut off. His price was even less than Brownells so at least my learning curve didn’t cost me too much.
I think everyone’s been there, even when they won’t admit it. Ever forget to put a check in the billing envelope, or have the remittance slip turned the wrong way?
Glad you got out of it without having to suffer too much. My practice to avoid this is a lot of pre-assembly and only reaching for the thread-locker after a full trial (partial disassembly required).
