why is my seating die crushing my brass?

[DocCarbon]

I've done it on 7.62x51mm cases ,by NOT changing seating depth when changing bullets . Also had an incorrect sizing ball in another Die . Seems someone swapped a sizer ball in a Die set and when I got the set of dies had NO clue ; Until I took it apart and measured it . Felt really stupid crushing #4 cases before it dawned on Me something was WRONG . Duh !.

 

[Old Navy]

I tried to seat a 6.5 CM in a 6.5X47 die once. I couldn't do it as good as you did. Only took one before the light bulb between my ears lit.

 

[CA_Shooter]

I drew what I had to do to fix this. The part that needs to be "raised up" was crushing the brass

 

[DukeDuke]

what I think happened is, my Forster sizing die was made for Lapua brass, Alpha brass has much thicker neck walls, so after sizing, the neck is super tight for the .243 bullet. During the seating process after the boat tail the resistance is too much and the shoulder collapses. Assuming I'm correct, would a bushing die solve this problem? The outside neck diameter of a sized case is .259, the outside neck diameter of a loaded one is .271.
I really appreciate your help!

 

[Old Navy]

You should be around .268 to .269" on your sized case.

 

[jasophil1]

Get you a set L.E.Wilson arbor dies .

 

[TheOtherZilla]

Maybe just maybe the brass is hitting the bottom of the die before the bullet is seated. Try putting an empty case in and see what hoppin.

 

[Old Navy]

Maybe just maybe the brass is hitting the bottom of the die before the bullet is seated. Try putting an empty case in and see what hoppin.

My thought exactly. I know it is super hard to do but sometimes it is necessary to read the instructions.

 

[jasophil1]

My thought exactly. I know it is super hard to do but sometimes it is necessary to read the instructions.

Hey that helps a lot.

 

[Bill Norris]

what I think happened is, my Forster sizing die was made for Lapua brass, Alpha brass has much thicker neck walls, so after sizing, the neck is super tight for the .243 bullet. During the seating process after the boat tail the resistance is too much and the shoulder collapses. Assuming I'm correct, would a bushing die solve this problem? The outside neck diameter of a sized case is .259, the outside neck diameter of a loaded one is .271.
I really appreciate your help!

So u have .012 neck tension? Thats alot.

 

[Old Navy]

You couldn't seat that with a Foster with out flaring the seating stem and sticking it in the chamber.

 

[DukeDuke]

My thought exactly. I know it is super hard to do but sometimes it is necessary to read the instructions.

not at all
non of this happened with brand new brass

 

[Murray Brook]

When you get this sorted out you should check the chamber in your rifle and make sure you have sufficient neck clearance . Loaded round at .471 seems a lot. Also a sized case at .259 seems small also. That could be your problem right there. It would seem that your bullet is doing the job of an expander. Not good. JMO

 

[CharlieNC]

not at all
non of this happened with brand new brass

Measure the neck OD of new brass vs brass you sized, that should confirm your suspicion that the sizing die is not correct for different make brass.

 

[divingin]

what I think happened is, my Forster sizing die was made for Lapua brass, Alpha brass has much thicker neck walls, so after sizing, the neck is super tight for the .243 bullet. During the seating process after the boat tail the resistance is too much and the shoulder collapses. Assuming I'm correct, would a bushing die solve this problem? The outside neck diameter of a sized case is .259, the outside neck diameter of a loaded one is .271.
I really appreciate your help!

Did you, by chance, decide to remove an expander from your sizing die? Can't do that, as the die is intended to size small, then the expander opens the case mouth back up. If you run it without the expander, the case mouth will be way too tight.

 

[Mike Casselton]

When you get this sorted out you should check the chamber in your rifle and make sure you have sufficient neck clearance . Loaded round at .471 seems a lot. Also a sized case at .259 seems small also. That could be your problem right there. It would seem that your bullet is doing the job of an expander. Not good. JMO

A sized case with a .259 OD sounds like you have a 6mm bushing in it designed for a BR case.


Start over from the beginning...

Look at your sizing die and make sure it's actually labeled for the cartridge you're trying to load.



I know, it sounds stupid, but verify it anyway.

^^^^^^ Read that again


If that's correct, then take it apart and make sure every piece of it belongs together.

People have been known to do a die cleaning session and assemble them with the incorrect parts.

For the seating die, do the same.


Then, put a case in the shell holder and raise the ram.
Back out the seating stem and screw the die into the press until it contacts the case mouth.
Back out one full turn.

If you have any loaded rounds or dummy rounds, drop the ram and change out to the dummy/loaded round. Raise the ram and screw the seater stem down until it touches the bullet.

At that point, your seater should be good.

Go back and test your sizer die and verify everything works properly.

Measure before and after and take notes. Your problem will expose itself.

 

[SKWERLZ]

I drew what I had to do to fix this. The part that needs to be "raised up" was crushing the brass

Years ago I did the same thing with a Forster seater.
I was new to the sliding chamber type seaters.

 

[Dave M.]

View attachment 1326573

Looks like an uncircumcised.308

 

[Bc'z]

Looks like an uncircumcised.308

It was really cold that morning.

 

[Dave M.]

So u have .012 neck tension? Thats alot.

That’s a ton of neck tension….and this is coming from a guy that preaches higher neck tension.