Essentially, I’ve ****ed up twice now. I am stupid.
Today, I was working on another AR build and got to the single most dreaded step for me -installing the RE. Basically, no matter what my tube gets a cant (which only happens from the threads breaking near the end plate nub). This time I set my torque wrench to 38 ft/lbs in attempt to not watch the tube rotate when torque is applied to the castle nut. Didn’t work, and I picked up a cant. Took it apart to try and fix it and sure enough, boom, slightly stripped threads.
I tried the Geissele Reaction Block, but it wasn’t strong enough to hold the tube stationary. Basically, I don’t know what I can do differently to get a perfectly straight buffer tube. I give up.
SOLGW tube w/ Impact Weapons QD Plate. The RE had some issues (small cosmetic, but SOLGW blew me off -side issue), but everything seemed to be right and tight. My best guess is that it’s me, but I can’t figure out what I am doing wrong for the life of me.
You’ve secured the RE, but not the receiver. Applying torque to the RE, which is in contact with the receiver end plate, and therefore the receiver, causes the receiver to accept some of that torque which causes it to rotate.
I don’t get too carried away with torque, I just use average-boy snug versus farm-boy tight, then stake or set screw. (I’ve pretty much gone away from staking and am using old style RE threaded retaining collars drilled for set screws.
When using the standard castle nut, I find it easier to use this wrench instead of my armorers wrench:
If you have the RE clamped in the Reaction Block it must be the receiver turning. The pistol grip should give you enough leverage to hold the lower straight while you tighten.
I do it incrementally, maybe 10 ft/lbs at a time. That way it helps me monitor and correct it. Going bit by bit with the torque eliminated any canting that would normally frustrate the hell out of me.
Also having a friend to hold the lower helps a lot too.
Without a fixture to hold both, just have to keep trying it until you get it done straight.
Could try sticking a mag block into magwell and using that to hold onto while tightening castle nut. Better yet, rig up another vise to hold the mag block for you.
Might be worth trying a little grease on the mating surfaces between the nut and end plate.
I’ve always done it with the lower in a mag block and then put the stock on to the tube. Hand tight the castle nut on and while holding the stock center. Use the wrench tight a little more and then torque to spec.
I clamp the lower in a Vise between padded vise jaws and I have a second person hold the receiver extension aligned by using my receiver extension alignment wrench while I torque the castle nut.
Colt has a special jig for this that I would love to have someone build for me.
Perhaps a bit of thread drift, but who actually uses a torque wrench on their castle nuts? The reason for the question is that I have never had a problem with a cant. I have a G RE block and Mag block and tighten by hand and give it a hard grunt while holding the grip. All mine are staked and I tighten the castle nut by feel. I have never had one come loose. I recall in an old thread IG said he never used a torque wrench and did it by feel. This is a timely thread because a few weeks ago, I decided to torque a castle nut to 39 pounds with my torque wrench. Maybe my set up was wrong, or I did something wrong or it was operator error, but in tightening with the wrench, I never got to 39—or maybe I wasn’t holding something correctly???, But I did get to a point where I knew if I continued to apply pressure, something would give and turn a nice day into an "Oh $%&^% day. I should have added that I have installed approximately 15 RE’s (new build) and have removed and replaced approximately 20.
Ive installed maybe 40-50 receiver extensions, which isnt a lot by some standards, but probably more than most. Ive used quite a few brands of receiver extensions and end plates as well, mostly all mil-spec size for what that means(because we all know mil-spec doesnt always mean full mil-spec with receiver extensions).
I put some aeroshell antiseize on, screw the RE into the receiver(with the detent, spring, end plate, and castle nut on obviously), run the castle nut down by hand to make sure everything is in place, then give her a few grunts on the armorer wrench. Never used a torque wrench. Then I stake them at at least 1 point and preferably 2. I have never, to my knowledge, canted an RE, stripped threads, or had a castle nut back off. My receivers sit in a magwell block in my vice, I have no fancy jig to hold it all in place.
I was able to get get 99% of the cant out (which was difficult because of the broken threads). I had to get a new end plate (nitrided) and my punch slipped out and sunk into my receiver. That’s my luck. I was close to giving up the whole building AR thing, but woke up this morning and practiced staking on two old end plates. In the back of my mind, when building these ARs, I am constantly thinking about how well and exacting you guys all build your ARs and try to get to that level; also, at the same time I think, “shit these guys would be laughing at me right now.”