Bumps and bruises of learning to build.

[Klem]

If your groups have blown out because of a can it could be because it is not exactly square the the bore. While it might not be baffle striking a bullet can still exit a slightly angled can with more gas on one side than the other.

After a session is there more carbon on one side at the mouth or a pattern of carbon, paint stripping on one side more than the other?
Are the holes in the target exactly circular?
Is it a screw-on can - they always come loose as they heat up?