Re: Cheetah Barrels
Posted: Thu Feb 20, 2020 8:57 pm
Today i got a good look at a 8.5 twist 7mm IBI barrel to be used in Fclass as a 284 Win 0.317" no turn chamber.
Looking from both ends in i saw no tooling marks anywhere. No chatter marks from the button or reamer in either of the grooves or lands which is a good indicator that those two processes are under control. This was a 5R button barrel where you could see a uniform radius on each land and each land was uniform for width along its length.
Looking down a barrel is not a science and no one can determine if a barrel is going to shoot or not.
Everything looks great with just the one comment i would make. After looking down virtually every brand of barrel at some point, the lapping in this barrel was done with maybe one grade too course lapping paste. The common belief is courser can be better as opposed highly polished. A finer grit of around 1000 or finer can lead to copper streaking that can be nighe on impossible to remove. Course will burnish, or that is the hope, but this barrel looks just a little too course where the sharp edge on the lands on the trailing side was rounded slightly. These should be sharp in a new barrel and not look like buttressed rifling when this barrel is meant to be a 5R. Dont get me wrong, a buttressed land is very strong and doesn't break off the edge easily, but this was not machined, it was worn to that shape.
My opinion only where shooting will tell.
Looking from both ends in i saw no tooling marks anywhere. No chatter marks from the button or reamer in either of the grooves or lands which is a good indicator that those two processes are under control. This was a 5R button barrel where you could see a uniform radius on each land and each land was uniform for width along its length.
Looking down a barrel is not a science and no one can determine if a barrel is going to shoot or not.
Everything looks great with just the one comment i would make. After looking down virtually every brand of barrel at some point, the lapping in this barrel was done with maybe one grade too course lapping paste. The common belief is courser can be better as opposed highly polished. A finer grit of around 1000 or finer can lead to copper streaking that can be nighe on impossible to remove. Course will burnish, or that is the hope, but this barrel looks just a little too course where the sharp edge on the lands on the trailing side was rounded slightly. These should be sharp in a new barrel and not look like buttressed rifling when this barrel is meant to be a 5R. Dont get me wrong, a buttressed land is very strong and doesn't break off the edge easily, but this was not machined, it was worn to that shape.
My opinion only where shooting will tell.