question on bedding the barrel extension into the upper

[A5BLASTER]

A5B:
What thickness stock did you use?
Any issues keeping the shim material in place while working the cold extension into the heated receiver?

I have two rolls of it one says 5 thousands and one says its 10 thousands. Just depends on the extension what thickness I use. Mostly use the thinner one.

I haven't had a issue with it moving while installing the cold barrel mainly because I use a couple of small drops of gel super glue to hold the seams down and keep it tight. I do this before putting it in the freezer. You dont want the ends to over lap each other and you dont want the seam on the top/bottom always put it on the side. I also cut a small section out of it to fit around the indexing pin.