Brass swelling

[Tundra Cruiser]

So had my Remington 700 7mm rum rebarreled to a 300 rum. I have coupe boxes of ammo through it. Started reloading for it the other day. Never payed much attention to the brass tell I started reloading. Any idea why brass is swelling so bad? Could it be the chamber is cut to big? The rifle shoots really good. Should I be worried?

 

[TwoMore]

Hello, what does it measure at about .200 from the base. 300 rum chamber should be around .551

 

[J E Custom]

View attachment 143129 So had my Remington 700 7mm rum rebarreled to a 300 rum. I have coupe boxes of ammo through it. Started reloading for it the other day. Never payed much attention to the brass tell I started reloading. Any idea why brass is swelling so bad? Could it be the chamber is cut to big? The rifle shoots really good. Should I be worried?

The chamber looks to big. But you have to measure the brass to make sure as Two More said. If it is accurate, don't worry about it. Only size enough to chamber and your brass will last longer because you wont be over working it.

J E CUSTOM

 

[Tundra Cruiser]

The average is .558

 

[Tundra Cruiser]

The chamber looks to big. But you have to measure the brass to make sure as Two More said. If it is accurate, don't worry about it. Only size enough to chamber and your brass will last longer because you wont be over working it.

J E CUSTOM

So should I buy a neck sizer and stop FL sizing?

 

[L.Sherm]

If it was me I would take it back to whoever rebarreled it and check the headspace. Sounds like one of 2 things happened either the reamer was run to deep or reamer is out of spec.
Make them fix it.

 

[Chamberman]

Either the reamer is out of spec, or they had to sand the chamber because of heavy reamer marks, they could have also dragged a chip while pulling the reamer out with the machine still spinning.. If they were using a flush system, it could have stopped and a chip was lodged..... Either way, if it gouged the chamber, they would have to try and sand it out, which would cause the chamber to go out of spec. Usually in these cases the barrel needs replaced or set back and re- chambered.

 

[BountyHunter]

Send your die back and have it honed out a little at the base if everything else checks out. RUM is just too powerful to neck size. You will end up downloading it to save the brass or just throwing brass away when it gets sticky. Key is correct fitting FL dies

 

[cohunt]

Saami spec is .5510 with a tolerance of + .002"

Are your pics before or after sizing? If after you may be "plowing" brass to the rear when sizing.

 

[J E Custom]

So should I buy a neck sizer and stop FL sizing?

You can still use the Full length die, Just don't go all the way down to the shell holder. Take the expander ball out and size one case just a little, try it in the rifle (Place the case under the extractor before inserting it in the action to prevent a false feeling trying to get the bolt over the extractor) and then try the case to see if it is tight, (Don't force it Because you want to just feel the cartridge when it chambers). if it doesn't want to go into battery easy, tighten the die a little more and repeat the process until you get the cartridge sized enough to chamber but not full sized.

This is normal if the tail stock on the lathe is not perfectly on the same center line as the bore The reamer will cut a larger chamber in the rear than the reamer.

The chamber looks rough but over time it will smooth out. Max loads are not recommended because they can be hard to extract. You can buy a go gauge for less than $40.00 and check head space if you don't have a smith handy.

J E CUSTOM

 

[TwoMore]

I just checked my .338 edge and my 7rumAI, both brass's measure .549 fired and my reamers are both .551 @ .200, sounds to me that the reamer is either over or it may not have been centered. I dont know what would be acceptable but .558 on the brass would put the chamber at around .560 and that doesn't sound good it would have to be way off on the headspace to get .560 both my reamers are .559 at the very back .500 from the stopping mark on the reamers

 

[TwoMore]

You can still use the Full length die, Just don't go all the way down to the shell holder. Take the expander ball out and size one case just a little, try it in the rifle (Place the case under the extractor before inserting it in the action to prevent a false feeling trying to get the bolt over the extractor) and then try the case to see if it is tight, (Don't force it Because you want to just feel the cartridge when it chambers). if it doesn't want to go into battery easy, tighten the die a little more and repeat the process until you get the cartridge sized enough to chamber but not full sized.

This is normal if the tail stock on the lathe is not perfectly on the same center line as the bore The reamer will cut a larger chamber in the rear than the reamer.

The chamber looks rough but over time it will smooth out. Max loads are not recommended because they can be hard to extract. You can buy a go gauge for less than $40.00 and check head space if you don't have a smith handy.

J E CUSTOM

I have 2 factory A-bolts that have very large chambers and that is how I load for them

 

[Tundra Cruiser]

Probably should have gunsmith replace barrel. I do feel better knowing it safe to shoot.

 

[CatShooter]

So should I buy a neck sizer and stop FL sizing?

YES!! If you FL the cases you will get head separations - neck size, and the cases will last a long time.