.300 WM mouth Bulge

[High H2o]

Hello reloaders,
I'll start by saying I've only been reloading for about 2 yrs., and apologize if this has already been covered elsewhere. When I full length resize once fired 300WM Hornady brass I get a bulge in the mouth of the case. When I full length resize virgin brass, this doesn't happen. I've tried two different dies (lee, Redding) , both with and without the expander ball, nothing seems to help. I use wax (very small amount) on the inside of the mouth every so often. Any ideas on why this is happening? some of the rounds are so bad, they won't chamber in the rifle they were fired in.
Any help would be appreciated!

 

[whiskeysierra762]

I'm not sure about why you are getting a bulge but have you tried a light taper crimp to remove it?

 

[jet_lagged]

Since this happens with fired brass, not new brass, perhaps the fired brass has "grown" in case legth, and the cases are now contacting the top of the die on the inside? They are getting rammed up into the top of the die, and are deforming as a result?

 

[lash]

Do you I.D and O.D. chamfer before sizing?

Oh, and check your overall case length as mentioned above.

 

[High H2o]

Hey, Thanks for the replies!
I trimmed them, After I sized them, didn't think to measure before resizing will have to measure that.
I Chamfer after sizing using a Lyman case prep station.

I've heard that Hornady brass is a bit soft, and was wondering if during the sizing process if maybe the mouth just buckled. I picked up some nosler brass, and I'll see if the same thing happens...Thanks!

 

[supercorndogs]

I don't see how a full length die could do that. The last thing the brass runs over, the expander ball, can not size something like that. I.E it would expand it uniformly. The part of the die that sizes the neck would iron that budge on the way out, if it was hitting something at the top that was belling it out. And the brass would not a hold a bullet if the neck sizing area of the dies was bigger than the expander ball. The brass look like you are running it into an M die.

 

[demolitionman]

Make sure your brass is entering the sizing die concentrically so it doesn't catch the edge of the expander ball going up......if there is a kernel of pow on the shell holder placing brass on it will can send it up at enough angle to dent one side or bulge one side. Now if this bulge goes around the entire mouth then I dunno man.

 

[6.5texas.shooter]

Are you tumbling in a stainless tumbler by chance? That may be the issue if they’re tumbled too long. Other than that.... check case length. But I’m still stuck on the fact it takes material from the inside to push to the outside (normal loading procedures observed). So I’m thinking tumbling is rounding edges. And the sizing ball is pushing the imperfections to the OD of neck