I'm at my whits end with buffer tubes

[Hulkstr8]

Hey guys,

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.

[Stickman]

I've seen it be a problem with lower end parts.... what are you using? The issue could be hardware, and not user inspired.

[Hulkstr8]

I've seen it be a problem with lower end parts.... what are you using? The issue could be hardware, and not user inspired.

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.

[Todd.K]

The only way to get it perfect is to use a fixture that holds both the lower and RE.

With the RE clamped, you just need to hold the pistol grip and keep the lower from turning as you tighten the castle nut.

[Hulkstr8]

The only way to get it perfect is to use a fixture that holds both the lower and RE.

With the RE clamped, you just need to hold the pistol grip and keep the lower from turning as you tighten the castle nut.

So you're saying the receiver is turning when I am torquing the castle nut, not the tube?

[grizzman]

I'd say you're not doing anything "wrong" at all.

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.

[26 Inf]

Get something like this to hold the buffer tube:

https://geissele.com/tools/reaction-...tube-only.html

https://www.botach.com/kley-zion-ar1...fer-tube-bock/ (cheaper option = I have this one and it works just fine)

Then, as Todd K. said just hold the pistol grip.

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:

https://www.brownells.com/gunsmith-t...prod16882.aspx (less than 10.00)

[Iraqgunz]

Yep, and we just did one in class today exactly like that. And it was basically perfect.

The only way to get it perfect is to use a fixture that holds both the lower and RE.

With the RE clamped, you just need to hold the pistol grip and keep the lower from turning as you tighten the castle nut.

[Todd.K]

So you're saying the receiver is turning when I am torquing the castle nut, not the tube?

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.

[bb223]

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.