450Bushmaster.net

I bought a Bushmaster 16 inch complete upper back in 2015. It broke on me (long story probably for another post), but now I found a 20 inch Bushmaster 450 barrel for sale at CDNN that I couldn’t resist.

So I plan on changing out the barrels, and re-using everything else except the gas block. The barrel is what went bad on the previous upper. The old syrac ordinance detent adjustable gas block I have locked up and the Allen screw stripped out.

I want to use an adjustable gas block but I saw a post somewhere on this site saying it is not recommended on this barrel because of the long dwell time on the 20inch barrel with carbine length gas system.

Questions:

-should I use an adjustable gas block and what brand/style is recommended. I’m leaning towards ODINWorks

-do I need to check headspace. I’m thinking I should buy a field gauge just to be safe.

I used a Bushmaster 20" barrel for most of my 10 years with this caliber and never felt compelled to use an adjustable gas block, despite trying a lot of different bullets and a few different powders. Ideally, a 20 inch barrel would have a mid-length gas system but I could count on two hands with fingers left over, where the carbine length system was not optimal over the years and only when pushing loads faster than they needed to be. I've never checked the headspace on an AR barrel/bolt combination that I put together, but that's just me.

My chrome lined barrel took about 100-150 rounds to feel like it was broken in. My SS Bartz barrel broke in a lot quicker. That said, its hard to beat a chrome lined barrel for ease of cleaning, even the copper buildup. BTW, never use a chemical copper remover on a chrome lined barrel. There's a copper layer between the chrome and the steel. You don't want to compromise that. JB compound or Remington 40X compound does a whiz bang job on copper buildup and speeds barrel break in.

Hoot