I have just acquired a A1 upper that had the bayo lug removed and a muzzle A2 type muzzle brake attached to it. I also received with it a F/H that looks like the 5.5" one but slides over part of the barrel to make it like the shorter one while it is 16". It is threaded .25 of the way from the end. I was wondering if one could make a plug for the inside were the slots are with an opening slightly larger that the projectile size and make it a muzzle brake or does the entire inside need to be filled to cover the slots? Thanks for any help. To be legal I was going to drill, pin and weld over the pin it on the barrel.

What Troy said, as always :D.

On the 22MM thing, it is PROBABLY better to go bigger, rather than smaller. That way they can't come back later and say "By the way, a grenade STILL slides over that muzzle device".

Scott

Thanks for the replies.  I will measure the diameter of i to see what size it is.  By the way who does make these type just in case?

I have a A2flahider type mzzle brake that is the same size as the one on the pre-ban Colt I sold.  The only difference is that the brake has a piece of metal at the end, but it still has the slots.  The 5.5" one is a little larger than both.  Of all times to not have a ruler anywhere in the house.  If a 9mm equals a .36 caliber, anything over .90 on an inch ruler should suffice.  I Intend to drill through and pin the device on.  If I go this route would I need to cover the slots in the hider or could I just make a end cap like on the A2 type one that it came with?  I tried Kurts forum for one but no reply.  Thanks guys.

Just measured and it is 1" which I believe works out to about 25mm.  Quess I will have to be patient.  Thanks