Karl, sorry for not responding earlier, just noticed your post.

It's not my gun and it has been about 10 years since I played with it.

The Barrel was made from a Gi Surplus Machine gun barrel. I don't know its length. I can tell you the Muzzle brake is a direct copy o f the KDF brake and is 4 inches long...and it works just well as those big tank gun brakes.

The main ammuniton we were using was Dominican GI ball. We did use some tracer one time in it and after that we were real carfull where we shot that gun. That tracer round bounced 3 or 4 times out across the Texas pan handle for long ways. What was scarey was that it bounce over the hillside we were shooting into.