View Full Version : Nuts and barrels

27 February 2015, 21:12
So, my class was canceled, and I had so many questions. So I've got an upper to assemble, and would like a recommendation or two.
I dont have the immediate ability to pin my gas block, and the barrel already has one dimple in it. I am assuming it's best to Rocksett both set screws.
Secondly, when mating the barrel to the receiver, do I do it dry, or with a thin film of lube. If lube, use the Molly grease I keep hearing about. Same for the barrel nut.
Thanks for the input.

27 February 2015, 21:19
The dimple with rockset should do you fine unless it's s duty upper. I always use some 33mm grease on mine but I'd recommend at least some type of lube, especially on the barrel nut.

4 March 2015, 18:55
Either blue Loctite or Loctite C5-A on the barrel extension when you put it into the receiver, C5-A on the barrel nut.

4 March 2015, 20:06
Hey Clancy,
class was cancelled huh? That sucks. I have rocksett if you don't already, and I also have the graphite free moly for the barrel nut, same one they recommended in the now cancelled class. I also have the Geissele reaction rod for ar15's you can borrow. I've used it on everything with good success.

We need to hook up one of these days at the range (I have suppressors to play with!! LOL)

4 March 2015, 21:10
Thanks Jim, but they are already on order. I should have the rifle assembled this weekend. Let's shoot when it cools down. This 35 degree weather is far too warm to spend outside at the range.

5 March 2015, 07:11
AeroShell 33MS for the barrel nut and I use it on the extension, too. You can get small jars for $4 off of eBay that will last you many builds. The military doesn't use loctite on the barrel extensions, so I don't either.

Here is a good write-up: http://thearmsguide.com/5758/build-ar-15-upper-receiver-barrel/

Since you live up north, here is another trick: if you are having trouble fitting the barrel extension into the receiver, use a heat gun to heat up your upper receiver. The thermal expansion should give you the extra bit of room you need to easily install the barrel.

5 March 2015, 10:53
AeroShell MS33 on everything that touches the barrel nut. We have a lot of aviation suppliers in the area so IIRC a 14 oz. tube runs about $15.00. The date on the tube I have is 2002 LOL

I know Bill Alexander claims lock tite on barrel extensions improved accuracy on barrels over 18" but I saw no effect but a mess to clean up after if it ever has to come apart.

5 March 2015, 12:19
Threadlocker anywhere on or near a barrel is going to melt. Loctite and similar compounds are not meant for high temperatures. Rocksett on the other hand is a ceramic-based adhesive meant for high temperature. It's great for muzzle devices and gas block set screws. High temp synthetic bearing grease works fine for the barrel extension, and it's super cheap at the auto parts store. Put a light coat on the receiver threads as well before you install the nut. That will make it easier to remove and your torque reading will be more accurate as well (you ARE using a torque wrench right?) [:)]

5 March 2015, 12:56
I was assuming you have a torque wrench, but if you need to acquire one I suggest: http://www.amazon.com/SK-Hand-Tool-76130-150-Feet/dp/B00EMIBWPS/ref=pd_sim_sbs_hi_4?ie=UTF8&refRID=1VK3655PMTKSKEAH4TG4

Reasonable cost, low/no maintenance (you don't have to worry about setting back to zero for storage), continuous readouts, and from a reputable manufacturer.

5 March 2015, 23:41
Thanks for the help. I d have a torque wrench, but my ALG EMR barrel has a timing/torque wrench and peel washers. My torque wrench isn't happy right now, it just wants to click.