^^^ Right. It's not fool proof. I still managed to send a detent into my chest, but it's far easier using this method. I'm a bit fumbly fingered sometimes.

quote:

Originally posted by Tirod:
Attached to the nut wrench it's not the same length and the exact reading anymore. Exceeding 85 is dangerous as you could strip the aluminum threads on the nose.

If you use the torque wrench properly the torque value doesn’t change.

If you put a wrench attachment (outside the gun world, crowfoot wrenches for use with torque wrenches are common) on a torque wrench at right angles to the torque wrench - so the fastener is on the line through the square drive that is perpendicular to the handle - the torque applied to the fastener by the wrench attachment is the same as the torque applied to the wrench attachment by the torque wrench.

I didn’t want to dig up my torque wrench, so I used a sliding T-handle, but it’ll do for a demo.

Torque value is wrong:



Torque value is correct:

No doubt start with a nice bench vise then utilize the stuff listed on DaBigBR's post which is nicely documented.
It's a nice start.
You will soon figure out what you need when you start building.
Let that experience educate you.

quote:

Originally posted by darthfuster:


You can do the pivot detent with a clevis pin. Watch it done on YouTube. Once I learned that method, it was easy.

Clevis pin…well don’t you learn something every day? Never knew they had a real name. Dad always just pointed to the pins on his Kubota when we’re would help him hook up the three point implement, said “gimme that pin”.

Seems if you had the right diameter it would work like a charm.

It really easy to make what you need easily do by drilling a hole in a piece of 1/4" rod stock, but to buy one what you want is a 1/4" clevis pin. I think the single hole ones are easier to deal with than the multihole ones.

The Magpul Bev Block is both a reaction rod and a lower receiver Magwell block. That and their multi tool can handle almost everything.

But I use the clamshells for barreling uppers and have never left a mark or damaged any upper. For the exact reason shown in the video above. I have gone all the way to more than 80 ft-lbs to time GI nuts that are just past time with the previous notch at 30 ft-lbs. I've had this happen with two different fixed front sight base barrels and multiple uppers I tried. Would have needed to go under spec to time them, but ended up at the top limit. Facing the upper or putting a 0.001 shim behind the nut would have helped, but that means pulled the FSB off which is a PITA. I have the tools for it and can do it though.

Worst case was trying to remove the barrel nut on my HK MR556. The gas block is canted a little in the clockwise direction and I wanted to check if the upper notch got wallowed out (or the pin broken) when they barreled it at HK. The barrel is notched to time to a key in the gas block before drilling and pinning it so it's not the gas block to barrel fit, unless it was machined out of time, or if the barrel extension is installed after the barrel is machined and timed to the gas block notch and hole.

Factory spec on these is 80 ft-lbs and I went over that by a decent amount and it didn't budge. I've heard they use a bedding compound on the barrel extension to receiver - probably something like Loctite 609 or 620 - and if any of that got on the threads that nut is not coming off without a lot of heat and torque. So I gave up on it. But the upper is fine, no marks at all from the clamshell.

I don't know about you but applying 80+ ft-lbs to the barrel extension lugs is not exactly the best sounding idea. And if you loosen the extension your barrel is done for. I'd rather ruin a $100 upper than a $300 barrel.

When using the clamshell, the only torque the barrel will put on the upper is from friction between the inner step of the nut and the flange around the barrel extension. Use plenty of grease on the front face of the flange and you won't have any problems. Dry, the friction might turn the barrel enough to damage the upper.