Get a different gas block or a different rail. If you want to get risky you could skim a bit off the gas block and rail.
Heat up the barrel (carefully) and freeze the gas block then tap it on (may have to use a brass punch), I had to do that on my AR build. Funny thing is once I got it on there I realized I put it on backwards...fail on my part.
Wait... wouldn't you freeze the barrel and heat up the gas block?
Wait... wouldn't you freeze the barrel and heat up the gas block?
Or you could just hand lap the inside of the gas block?
That would work, our just use a dowel rod and rap emery cloth around it...I ended up using a polishing wheel with a Dremel to smooth mine out a little as well.
Thanks. If I could say one thing rock river does a great job installing free float tube !! They had enough lock tight I had to heat the crap , out of it to get it off !!
I haven't changed mine, but on the 458 SOCOM forum, it's been said they use loctite by the 55 gallon drum and have a guy with tree trunks for arms tightening the tubes! The upper looks good. What are you going to run for optics?