Bulging at the bottom of the shell

[Flywire]

Probably an incredibly noobish question but is it normal for a shell to bulge about 1/4" from the rim in a .303? its a well defined line where the brass looks different. Ive been having some accuracy issues with my no1mk3 and thought this may be an issue...and help would be greatly appreciated, thanks guys

 

[OKTREE]

Mine has done the same thing from day one. The 303 typically will have a very loose chamber.

 

[shotgunjoe]

This is normal for a lot of different calibers, it depends on how loose the chamber is cut and how straight it is. It is also a good reason for neck sizing as the brass does not get worked as much.

 

[mooncoon]

you seem to be describing a gun with excessive headspace. The different coloured area, I would probably describe as a bright ring and represents where the shell has stretched. I would suggest annealing your brass and only neck sizing from now on with the hope that the shell will index on the shoulder instead of the rim.

cheers mooncoon

 

[glycerin]

Sloppy(wide) chambers don't have much to do with headspace. A No.1mk111 with perfect headspace could still bulge like crazy. X2 on neck-sizing and annealing(sometimes). Good luck

 

[Tex Critter]

It could be leading up to Incipient case head separation

 

[Hotwheels81]

It could be leading up to Incipient case head separation

pretty much every .303 milsurp rifle does this to some extent.... my old No1 mkIII chamber is actually a little out of round and leaves a ring around the bottom of the case.

straighten out a paper clip and bend about 3/16" of the end at 90* and scratch the inside of the case were the line is... if you feel a noticeable bump inside the case flatten the case with a hammer and toss it in the scrap bucket.