Thread: Barrel-bore enlargement

Originally Posted by Toby

What do you mean by the barrel "opening up?

Some barrels will open up at the end of the barrel where the thread is cut due to bigger bore size eg 30cal and to much steel taken off from the outside due to thread. On smaller contoured barrels.

This is copied from D Maiseys website;
All DFM muzzlebrakes feature an internal shoulder, so muzzlebrake can be seated either in the conventional manner to pull up tight on the 'shoulder', or on the muzzle/nose (actually the best method). This permits the gunsmith to use the maximum thread size possible for the diameter of barrel at the muzzle. This provides better strength, less chance of barrel stretching (due to unnecessary over-tightening by rough operators), and less chance of the barrel-bore enlarging under the threaded section at the muzzle (common problem on button-rifled barrels).

There is another article on accurateshooter.com if you feel the need to know more.