Phil,
Those specs appear to be fine, and your bump is safe - but not optimum.
SAAMI permits a maximum case stretch of 0.0171" for the 6ARC. This from the deepest acceptable chamber (1.2001"), firing the shortest acceptable cartridge (1.183"). If you had such a chamber and then bumped the spent cases back to SAAMI they wouldn't last long. But after first firing, then bumping only .003-.004" for a gas gun, or even less for a bolt gun, they would be fine. Using recommended bumps as a benchmark you can adjust the bump to whatever is the most reliable in your gun, for longest case life. Whatever you end with will be close to the recommended bumps for gas and bolt guns.
In your case you are currently bumping .0075" so can improve case life by unscrewing the sizing die slightly to halve that. Given the die is slightly tapered, backing it out will also help with the axial squeeze that you are concerned about. After lessening the bump to .003" can you post a photo of what rings (if any) you are now getting.
Those specs appear to be fine, and your bump is safe - but not optimum.
SAAMI permits a maximum case stretch of 0.0171" for the 6ARC. This from the deepest acceptable chamber (1.2001"), firing the shortest acceptable cartridge (1.183"). If you had such a chamber and then bumped the spent cases back to SAAMI they wouldn't last long. But after first firing, then bumping only .003-.004" for a gas gun, or even less for a bolt gun, they would be fine. Using recommended bumps as a benchmark you can adjust the bump to whatever is the most reliable in your gun, for longest case life. Whatever you end with will be close to the recommended bumps for gas and bolt guns.
In your case you are currently bumping .0075" so can improve case life by unscrewing the sizing die slightly to halve that. Given the die is slightly tapered, backing it out will also help with the axial squeeze that you are concerned about. After lessening the bump to .003" can you post a photo of what rings (if any) you are now getting.