AR Barrell/flash suppressor question

[psion_008]

Hi all,
When Replacing the gas block with a low profile block last night it came to my attention that my barrel's end was not threaded back the whole way. The peel washer wasn't big enough to even touch the flash hider. The Crush washer went back on :/

Is this a common problem on newer DPMS barrels?
Who makes flash hiders that have a deeper seat?
Do I need to get the end retreaded?

[Fragger]

I've recently noticed on a very nice and well known aftermarket muzzle attachment to not want to thread back far enough to tighten up.

A simple fix for this was to add a bit of chamfer to the first thread on the brake.