Ya ever have dies stretch your brass?

[Smokinyotes]

So here is the story. After resizing my 257 wby brass the case length was +- 2.552” so I would trim them back to 2.540”.
After reloading and firing I checked and the fired cases were 2.540”. I tried to chamber them and they chamber just fine so I thought I would back my sizing die off about a turn just to resize the neck. Tried this and they wouldn’t chamber.

I measured the brass and it was 2.552”. I brush and lube the inside and outside of the neck and case body with Hornady one shot. I thought possibly the expander ball was too large and stretching the necks so I removed it and tried it and the brass is still being stretched to +- 2.552”

So the only way I can get them to chamber is to do a complete full length resize then trim them back to the 2.540”. Thinking this is stupid resizing and trimming when I only need to be neck sizing I phoned up Clay and told him to send me a 257 wby Redding neck size die.

I’m not sure if it is the soft Nosler brass or the die but I’m hoping the Redding neck size die solves the issue.

[Opalsasquatch]

Is the body of the case still being sized with the die backed out? As in, change in diameter from fired to partially resized case? Could be moving the shoulder forward.

Neck die should solve your problem I would think


"Shuuuuuuussssshhhhh.

You can't post stuff like that, too many heads will explode."
Hillbillyreefer

[Smokinyotes]

Originally Posted by Opalsasquatch

Is the body of the case still being sized with the die backed out? As in, change in diameter from fired to partially resized case? Could be moving the shoulder forward.

Neck die should solve your problem I would think


"Shuuuuuuussssshhhhh.

You can't post stuff like that, too many heads will explode."
Hillbillyreefer

Yes it’s pulling the shoulder ahead just enough that you can’t close the bolt. I have to have the die screwed down tight to the shell holder to get them to chamber.

[260 Rem]

Am I understanding that the resize process with the die backed off to neck size only...is pulling the shoulder forward...resulting in no headspace? And you need to trim each reload, or just the first time?

[Smokinyotes]

Originally Posted by 260 Rem

Am I understanding that the resize process with the die backed off to neck size only...is pulling the shoulder forward...resulting in no headspace? And you need to trim each reload, or just the first time?

Yes that is correct. Even with the die backed off and expander ball removed it is stretching the brass about .012. And have to trim after every resize. The brass is not stretching when being shot as it measures 2.540, then after full length or partial sizing the brass is +- 2.552

[260 Rem]

Sounds like the case walls must be thick...and on a FL resize, the brass has to move somewhere ... and the only way for it to go is forward. Would expect the need to trim should be less each time. Not that it is worth getting for a single lot of brass, but Redding makes shell holders of different thicknesses so the shoulders can get bumped back a bit further. They come in .002” increments.

[Dean2]

I also shoot a 257 but this happens with many other cartridges as well, belted or not.. Your problem is that even backed off a full turn, the case body is still being resized, at least partly, by the FL sizing die. This happens when you have a chamber a bit on the larger side as the FL die is usually built to SAMMI min measurements to ensure a fit in ALL 257 Chambers. As you push the round into the die it squeezes down the shoulder body junction, which creates the effect of pushing the shoulder forward and lengthening the overall cartridge length. The shoulder does not get pushed back into place as the die is turned out 1 turn. If you FL size the brass they will fit fine again, and likely won't need trimming except every third or fourth shot.

That said, FL sizing you are working your brass a lot more than it needs to be because every shot the brass will have to expand to fill the full chamber. Might as well just leave it where it is once formed.

The neck only die will solve this problem.

[Smokinyotes]

Thanks Dean. The brass I’m using has been fired 3x in this rifle and I’ve had to trim after each resize. After having to trim so much was the trigger that got me thinking “this is crazy”, so I decided to measure the brass before resizing and found it to be 2.540”. I thought by backing the die off and just sizing the neck would eliminate the problem but really didn’t make any difference.

My neck die came in the mail last night so I’m hoping it solves my issue.

[Bushrat]

Originally Posted by Dean2

I also shoot a 257 but this happens with many other cartridges as well, belted or not.. Your problem is that even backed off a full turn, the case body is still being resized, at least partly, by the FL sizing die. This happens when you have a chamber a bit on the larger side as the FL die is usually built to SAMMI min measurements to ensure a fit in ALL 257 Chambers. As you push the round into the die it squeezes down the shoulder body junction, which creates the effect of pushing the shoulder forward and lengthening the overall cartridge length. The shoulder does not get pushed back into place as the die is turned out 1 turn. If you FL size the brass they will fit fine again, and likely won't need trimming except every third or fourth shot.

That said, FL sizing you are working your brass a lot more than it needs to be because every shot the brass will have to expand to fill the full chamber. Might as well just leave it where it is once formed.

The neck only die will solve this problem.

This. Easy way to tell, measure the diameter of the fired brass and the resized brass at the outside of the shoulder case body junction and measure the shoulder length from the base. The resized brass shoulder diameter will be smaller diameter even though your intending to only resize the neck, the brass outside diameter of the shoulder is being squeezed down by contact with the die, forcing the shoulder to move ahead.

[lclund1946]

As Bushrat explained the die is sizing the diameter of the body/shoulder junction which forces the shoulder datum forward and it has to be pushed back until it fits back in the chamber. Partial full length sizing does not work, in most cases as FL dies are usually cut 0.001 + under Saami Maximum Cartridge dimensions. Saami Minimum Chamber dimensions are usually 0.001" over that with Maximum chamber dimensions 0.002" over Minimum. This leaves 0.004 + if you have a Sammi Max chamber.

Most people believe that the shoulder/body length has to be "bumped", or shortened, to create HS but that is not true. HS can be created without moving the shoulder/body junction by decreasing the diameter here and at the neck. HS, measured at the shoulder datum, can actually be longer on the sized brass than one fireformed to the chamber.

The belted magnums have a much greater tendency to have problems like you are experiencing as tolerances are actually quite great. Starting with the 0.004" HS tolerance at the belt and adding 0.007"at the shoulder , from Max Cart to Minimum Chamber, means the shoulder can move forward even more than 0.011" in a Max chamber. As the following diagram shows the shoulder diameter can expand as much as 0.007"+ from F L to fireformed. Also the diameter of the base, just ahead of the belt, can vary by that much depending on pressures being run.
[IMG][/IMG]

As suggested the best way to solve the situation is to go to Neck Sizing. However if you started with new brass and did a ladder to find the pressure at which the brass fireformed to just under Saami Maximum Cartridge specs at the shoulder (0.492") and base (0.512") you could likely use the FL die. You would have to back it out until the brass just forms to fit in your chamber. Of course you will likely not be happy with the velocities you obtain as you will likely be at a starting load. However you will be using FL dies as they were meant to be used and running pressures that will not destroy your brass.

[Smokinyotes]

I fired a few shots today from the 257 wby. After firing the brass measured 2.542”. It chambers fine so I ran it through the Redding neck sizing die and re measured. Still measures 2.542” Problem solved.