6.5 PRC shoulder crushing issues

[Schmo]

I’m having issues with shoulders crushing when trying to reload virgin Peterson 6.5 PRC brass using 147 ELD-Ms. I ran them through an RCBS FL die, but that doesn’t fix the problem. Bullets measure .2635”, and neck ID measures .258-.260, even after a pass through the die. I’ve even tried lubing the necks, and still get a shoulder crush. Expander button measures .263”. I’ve even run them through a .264 mandrel, all with no positive effect. What next?

 

[fuzzymarindave]

You can push a .264 mandrel down the neck without issue but when you push a .2635 bullet into a case the shoulder deforms ? Try lubing the base of the bullets too. I prefer graphite powder. I think new brass can be grabby without any carbon (or lube).

 

[Schmo]

I’ve tried case lube inside the neck, and I’ve also tried graphite on the bullet. Yes, can run the mandrel, but it’s taper is more gradual than the bullet.

 

[king402]

Do you think you're getting too much lube on the case neck? I had a few cases get crushed and removed the lube (there was still a little residue inside the sizing die) and that worked for me. I've found its a delicate balance of not enough vs too much lube. Just a thought.

 

[Schmo]

Do you think you're getting too much lube on the case neck? I had a few cases get crushed and removed the lube (there was still a little residue inside the sizing die) and that worked for me. I've found its a delicate balance of not enough vs too much lube. Just a thought.

I don’t think so. I’m pretty used to loading for rifle, and haven’t had this much trouble before. The necks are 4-6 thou undersized.

 

[king402]

I don’t think so. I’m pretty used to loading for rifle, and haven’t had this much trouble before. The necks are 4-6 thou undersized.

Strange. Lets us know what you find when you figure it out!

 

[Odd1out]

If you have a brass tumbler, get some flitz green tumbler media additive. Squirt some in the media and let it run for couple of hours. Then throw your brass in there for 30 mins. It sounds like your new brass is too clean and super sticky. Alpha munitions has a video on this. If u get dry neck lube, get some rubbing alcohol. Put the alcohol and dry lube in a container. Use a q tip to apply. The alcohol will evaporate, but the dry lube will stay where you put it.

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[Harvey_NW]

I know this sounds stupid, but is your die set properly? I typically set up for ~.004" of interference, and the only time I've crushed a shoulder is when the die is improperly set where the case mouth contacts when seating. There is no way you can crush a shoulder by seating with only .001" of NT/interference.

 

[Schmo]

I know this sounds stupid, but is your die set properly? I typically set up for ~.004" of interference, and the only time I've crushed a shoulder is when the die is improperly set where the case mouth contacts when seating. There is no way you can crush a shoulder by seating with only .001" of NT/interference.

Shoulder crushes well before the handle stroke is completed, so it’s not an improper die depth. Also, NT is 4-6 thou, not 1 thou as you mentioned. Even after running them over a .264 mandrel, they’re springing back to 4-6 thou undersized.

 

[fuzzymarindave]

I’ve tried case lube inside the neck, and I’ve also tried graphite on the bullet. Yes, can run the mandrel, but it’s taper is more gradual than the bullet.

Just for the new brass you might pick up another mandrel slightly larger in diameter to reduce interference with bullets.

 

[Schmo]

Just for the new brass you might pick up another mandrel slightly larger in diameter to reduce interference with bullets.

I’ve wondered about that. Maybe a .266 or .267?

 

[Lawnboi]

First, sizing it did you no favor. Peterson in a saami cartridge should not need sizing. You likely worked the crap out of the neck for no reason, which may not be helping you.

Most premium brass comes annealed. Grab a new piece of brass and feel the friction of the annealed portion compared to the body. It’s the same inside the neck. You can have proper interference or neck dimensions and still have extraordinary seating pressure just due to friction.

To combat this you can use a mandrel, I’d use a wet lube, I don’t think dry lube works well enough, lots do but I had issues consistently.

Dry tumbling in semi dirty media will smooth out the inside of the neck, remove the lube.

Chamfer and debur and you will have consistent, not overly hard seating.

 

[Schmo]

First, sizing it did you no favor. Peterson in a saami cartridge should not need sizing. You likely worked the crap out of the neck for no reason, which may not be helping you.

Most premium brass comes annealed. Grab a new piece of brass and feel the friction of the annealed portion compared to the body. It’s the same inside the neck. You can have proper interference or neck dimensions and still have extraordinary seating pressure just due to friction.

To combat this you can use a mandrel, I’d use a wet lube, I don’t think dry lube works well enough, lots do but I had issues consistently.

Dry tumbling in semi dirty media will smooth out the inside of the neck, remove the lube.

Chamfer and debur and you will have consistent, not overly hard seating.

Gotcha. I was told to always size new brass to make it consistent, but maybe that’s incorrect. Neck ID measures basically the same before and after sizing or running it over a mandrel. Only have wet lube and graphite powder currently.

Are you saying I need to lube it, then run it in the tumbler for awhile to clean the annealing?

 

[Lawnboi]

Gotcha. I was told to always size new brass to make it consistent, but maybe that’s incorrect. Neck ID measures basically the same before and after sizing or running it over a mandrel. Only have wet lube and graphite powder currently.

Are you saying I need to lube it, then run it in the tumbler for awhile to clean the annealing?

Common practice when premium brass wasn’t a thing to size, not so much anymore with lapua, Peterson, alpha.

Wet lube on the mandrel and inside the neck. Run the mandrel through it. Dry tumble it for an hour or so and chamfer it. I’d bet that fixes your problem.

 

[Schmo]

Common practice when premium brass wasn’t a thing to size, not so much anymore with lapua, Peterson, alpha.

Wet lube on the mandrel and inside the neck. Run the mandrel through it. Dry tumble it for an hour or so and chamfer it. I’d bet that fixes your problem.

Okay thanks! Got some in the tumbler now.

 

[TaperPin]

Shoulder crushes well before the handle stroke is completed, so it’s not an improper die depth. Also, NT is 4-6 thou, not 1 thou as you mentioned. Even after running them over a .264 mandrel, they’re springing back to 4-6 thou undersized.

I’m confused. Is the shoulder crushing during the sizing operation or bullet seating? All the talk about neck diameter and expander mandrel has me confused if the shoulder is crushed well before bullet seating. Do you have a picture of a case with the crushed shoulder since that term means different things to different people.

There’s absolutely nothing wrong with full length sizing new brass - how else do you get a neck tension the same as your reloads?

If the sizing die is pushing the shoulder back too much your die is not adjusted correctly regardless of position of handle. If there is a machining mistake and a ridge in the die is snagging the necks, there’s no fix for that. Have you used a flashlight and looked in there? Take out your expander/decapper completely and run a case in. Is the expander button too close to the neck portion of the die and jamming the neck?

If you aren’t able to run a case in with the decapper/sizer button removed your die is not right. A new case should go in a FL die with little contact or effort other than the neck being resized. RCBS has been sold to new owners and it is not the same old RCBS that the reputation has been built on.

If the shoulder is being crushed as you seat bullets it’s usually because the die is turned down too far and the die is trying to crimp the bullet.

 

[JGRaider]

You're likely getting some spring back from that new brass. I use a neck sizing die and have never had any issues with my 6.5 PRC brass. You obviously need a bigger mandrel.

 

[Schmo]

@TaperPin,
The crush is happening during the bullet seating process, early in the stroke. I understand why you were confused

 

[Schmo]

Here’s a pic of the issue. I did what Lawnboi suggested. Lubed inside the neck, then ran it over a mandrel, then dry tumbled with polish for awhile. My mandrel is a .262”, not a .264” like I thought. What size of mandrel should I go to?

 

[Muledeerfanatic]

Man that is some soft brass