bulging at the base of the neck in a 243 win

[MNbogboy]

I'm having the same problem loading .260 rem. The fired case ejects/rechambers perfectly. I full length resize with Redding dies. A resized case chambers fine. Seating a bullet causes a bulge at the neck/shoulder junction creating noticable bolt closure resistance. Worst case the bolt won't close. I can't solve the problem either. Called Redding but their recommendation didn't work. Using Nosler brass, 3-4 firings.

Tree farmer,
Yours sounds like typical "donut". Hard chambering on loaded rounds can possibly drive up your pressures.
My fix for this has been to ream before sizing and after sizing with 2 different reamers.
You will have to measure your brass just inside the neck at both stages to determine reamer sizes.
This has worked for me on one of my 257 Bob A.I.s and my 6.5/257 Bob A.I.s as well as one 260 I had.
The donuts on the Bobs were caused by being formed from longer (270) brass. The 260 donuts I believe were caused by mixing neck sizing and full length sizing.
Donut formation seems to dissipate with seasoned brass. Annealing often may accelerate it.
Imho,
Randy

 

[Methow Packer]

This might seem a silly question but, have you flipped the bushing? The size stamp should be up when place in the die. Good luck with this issue.

I've always had the label up but tried it the other way to see. I did however figure somethings out that has fixed the problem. So far. A third time fired Lapua case through the body die to bump the shoulder back, but this time I back the pressure of the ram back some. Still having cam over but with a lot less pressure. So far so good. Still could run a bullet up and down the neck ,so no inner donut. Then I neck sized with lube of course with a .002 bushing but with less than a full throw. Some where around 2/3 or so resized neck length. Chambered. Perfect!! No donut on the outside at all. Smooth no friction chambering. So probably too heavy a ram pressure did something to the die to case relationship. As well as not fully resizing the neck down to the shoulder. I wanted to share this for other members who has responded with similar problems.

 

[Innovative]

TxPhred . . . .

Your picture looks like the case neck has small drops of water around the outside. You can't "see" a donut. They are only visible inside the case (at the base of the neck), and you need to measure the case ID to know if your case has one.

Most shooters see little or no effect from donuts, because most production rifles have extremely generous neck clearance. The advantage of a tight neck chamber is outstanding accuracy. However, you can experience weird symptoms when the neck ID and throat clearance are not exactly right.

 

[ShtrRdy]

This might seem a silly question but, have you flipped the bushing? The size stamp should be up when place in the die. Good luck with this issue.

I was wondering about this. My thought is that the size stamp should be down. This would allow the smooth surface on the bushing to contact the die plug and hopefully making the bushing squared up to the case neck.

 

[Methow Packer]

I've always had the label up but tried it the other way to see. I did however figure somethings out that has fixed the problem. So far. A third time fired Lapua case through the body die to bump the shoulder back, but this time I back the pressure of the ram back some. Still having cam over but with a lot less pressure. So far so good. Still could run a bullet up and down the neck ,so no inner donut. Then I neck sized with lube of course with a .002 bushing but with less than a full throw. Some where around 2/3 or so resized neck length. Chambered. Perfect!! No donut on the outside at all. Smooth no friction chambering. So probably too heavy a ram pressure did something to the die to case relationship. As well as not fully resizing the neck down to the shoulder. I wanted to share this for other members who has responded with similar problems.

I realize the brass is growing forward to the bace of the neck creating this donut. I can't make it go away without reaming the inside as suggested by Innovative. I'm buying a Le Wilson trimmer and the reamer to fix the problem

 

[George Dean]

I enlarged that pic quite a bit with my phone. It's just barely visible looking at it on my bench. Even my twice fired brass still hasnt all fully expanded to chamber dimensions and I've got a minimum spec chamber. Havent begun bumping shoulders back on any of it yet. Still have @ .001 to go.....

Maybe this is a better (enlarged) view.

 

[Innovative]

This is a much better picture. If all of your FIRED cases look this way, it is because your chamber is cut to imprint that shape on your case. If your RESIZED cases look like this, it is due to brass migrating forward on previous firings.

It's as I said earlier, your case necks appear to have this condition called a "donut".

 

[MNbogboy]

Can you post a picture of a fired case before sizing?
Like Innovative stated if these are your sized cases the expander mandrel pushes the migrated brass outward from the inside out.
The bulge would account for the hard chambering. If it was sized the full length sized the bushing would push the bulge inward.