I'm using up some parts I have laying around and I'm lacking 3 things.  A barrel,  buffer spring and buffer.  Have an old Colt 4 position stock and tube and am going to go with an XM177 copy - 11.5 in with the permanent attached FH to 16.5 in (dog gone local Sheriff )

What do you gurus think I should use for a buffer on this config? H, H2, H3 etc - I'm guessing a standard spring will be sufficient.

Also - was the twist rate of a "proper" XM177 1/12?

Thanks in advance

I think a heavy H buffer along with a new carbine spring will work great.

thanks Chris - appreciate the help

yes 1/12

ive got a 9mm buffer in mine left over from my 9mm carbine