I have built a aero m5e1. I used this barrel. Got it all assembled and noticed there was around .020" of rotational play when the barrel was full seated in the upper receiver. Using the correct lube, I torqued the barrel nut to spec and the barrel canted. The gas block (sl) is bolted down correctly in the correct location.

Any ideas to correct this, shimming it maybe?

Something is very wrong...there should be a raised pin on the barrel extension that fits into a slot on the upper receiver which prevents this type of rotation. You should probably take it to a gunsmith for a proper evaluation.

I hate to do this to you...but can you pull the barrel and take a pic of the barrel extension?  Specifically the TOP of the extension where the locator pin should be.

I took it all back apart and cleaned the grease off of everything including the extension and in the upper receiver where the extension goes in. I lubed the threads again and where the barrel nut contacts the barrel.

I kept working the barrel back after it moved when the nut was turned and was able to get it tight without it twisting. I think the extra friction of the extension in the receiver plus making sure the contact area of the barrel nut/barrel was well lubed. It's straight now.I do think the slot machined in the receiver is machined too wide by a little.

If you are at torque and straight, you should be good to go.



Glad you got her!!!!  Good job!!!