Changing Uppers Help

johhny12gauge

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Hello, I have a complete upper/lower 20" Bushmaster Hbar 1:9 AR-15. I am interested in getting another complete upper either 16"or 10.5" 1:9. Are they fully compatible or will I need to swap out any parts to make the set up functional? The shorter upper would be used primarily for a CMMG .22 kit I already have but possibly for .556 as well.
Thanks for the help CGNers
 
The only thing I can think of is you might have to change the buffer. Typically a 10.5” barrel will require a heavier buffer, which is assuming you have a carbine buffer currently.

I am not sure what additional changes have to be made for a CMMG .22 kit, I imagine everything is included in the kit.

2.23/.556 uppers should just swap out.
 
A 22LR kit will only need you to switch out the Bolt Carrier group with the 22LR bolt carrier which is the kit, oh and have a the 22LR magazine.

A 10.5" upper *should* use an Heavy or H2 buffer.

The Bushmaster lower uses standard mil-spec "small" pin size. Other than Colt, all uppers will match the "small" pins.
 
The buffer will be a rifle length buffer. For the most part those are all the same with the rare exceptions of hydraulic buffers or something like that.

The rifle lower should work with most carbine length uppers.
 
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