What caused this?

[mc1119]

So I reloaded some lapua brass and I have 2 cases of 24 that won’t load(chambers but bolt will not close/lock over)at all, and 2 that close stiff.

I did the sharpie test to see where it’s binding and in the photo you can see the round on the left is marking at the bottom of the shoulder(loads but is a stiff close of the bolt), on the right you can see the difference(loads but bolt will not close/lock over). It almost appears as the shoulder is malformed?

Prep of the brass was neck sizing, never fired prior. I’m guessing I should have done a FL sizing?

Any idea what caused this? What I should do to correct?

 

[Muley Buck]

The brass needs to be ran through a full length size die or a Redding body die, and measure as to make sure it bumps the shoulder back .001-.002.

 

[mc1119]

Do you still bump the shoulder on new unfired brass?

If I can deprive these cases will FL sizing resolve?

 

[Rich M]

It will fix your problem. You have to size new brass. Neck size after you’ve fired it in your gun.

you can deprime and size without issues. I’ve not had any go off doing that.

 

[Lawnboi]

What caliber are you loading? Something looks messed up. That much deformation caused by unsized virgin Lapua?

 

[Muley Buck]

Do you still bump the shoulder on new unfired brass?

If I can deprive these cases will FL sizing resolve?

Yes and yes.

 

[mc1119]

Thanks all! Appreciate the feedback as I am still learning this hobby.

 

[B23]

Prep of the brass was neck sizing, never fired prior. I’m guessing I should have done a FL sizing?

Did you use a neck size only die or did you just back the FL die off a little and you're calling that neck sizing only?

 

[mc1119]

Did you use a neck size only die or did you just back the FL die off a little and you're calling that neck sizing only?

Neck size only die as I didn’t want to work the new brass, but wanted to ensure the necks were uniform for loading.

 

[BjornF16]

What brand of dies?

 

[mc1119]

What brand of dies?

Redding premium series deluxe 3 die set.

 

[tdot]

From the pictures, I'd guess that the bullet partially deformed the neck as it was being seated. Was there an unusual amount of resistance during the seating process?

Did you chamfer the inside of the neck, prior to loading the bullet?

Personally I use a mandrel to uniform neck tension, not a neck sizing die. I also use it after full length resizing of the case, instead of using the button in the full length die. Easier and more consistent reloading imo.

 

[Pickettpuncher]

I agree with everyone saying you need to resize new brass. You do not need to deprime any that’s already primed tho. It can be done with primers in. I would also check brass length cause I think it’s possible some pieces are hitting the crimp stage in your die. Make sure lengths are correct and back the seating die out a half turn.

 

[Gunnersdad49]

I always full length resize all of my rifle brass. I haven't seen any major benefits to neck sizing only, and I consistently get 100% of rounds to feed and fire. It looks like your shoulders were not consistent. Neck sizing is to reload stuff that is already fireformed to your chamber, so as mentioned above, I would at least full length resize your fresh, unfired brass.

 

[nhyrum]

To me it looks like your bullet seat die is screwed down too far, causing the crimp to start while the bullet is still being seated

Sent from my SM-G996U using Tapatalk

 

[Vern400]

All responses are great. Stiff bolt changes to " cannot close bolt over 0.0010 to 0.0015 inch. Push your shoulder back 0.003. then check

Run the full length resizing die down with the ram up, til it hits hard by finger tight. Lower the ram. Back the die out a little (1/4 turn). Your dies move 1/14 inch (0.071) per turn so this is super sensitive. Resize the case and check it in your gun. The case that WONT close in the chamber.

If nothing changes you did NOT push the shoulder back. If it the bolt falls shut you may have gone too far. You find the setting that JUST pushes the shoulder back far enough to chamber. Ideally you just want a few thousandths of running clearance.

You CAN cram the FL die to the lowest setting. But depending on your gun, dies, and press, the shoulder has to "blow out" or stretch to fit the chamber every shot. That stretching is what causes head separation of the case. So if someone says "no, you don't have to do all that painstaking stuff" they're right. But the result of just cramming that shoulder back is your Lapua brass may not last long. And you might have a head separation. See that little hole in your receiver on the side? Where the bolt locks? Picture high pressure gas coming out there. It's bad bad. Personally I'd rather my brass wear out by primer pockets getting loose, or case neck splits. Neither is super dangerous really.

I recently quit neck sizing because my shoulders blew out tight and hard bolt closing happened. Now I push my shoulders back 0.002 or 0.003. More or less that is what most winning precision shooters do, though they have better tools than I do. I had the problem because I ran low and blew some ammo through a different gun. Even though they're both M700 actions, they're headspaced a few thousandths different. That screwed up my brass tracking.

When you get the dies dialed in, lock them down hard if you're only reloading for one rifle.

Hope that helps. I'm just an ol' country boy but I can almost reload and shoot pretty good.

 

[mc1119]

Update/fix:
Bullet puller showed up today.
pulled the bullets, emptied the cases, FL die shoulder bump.
problem solved!
Thanks all!

 

[Rich M]

Excellent!

 

[Harvey_NW]

Just tossing out that I've never sized new brass, ever. I understand the concept, and I definitely recommend getting a comparator and bullet/bump gauges so you can accurately measure, but USUALLY new brass is under dimension and just needs to be ran over an expander to straighten out any dings in the neck. Makes no sense to smash the shoulders down even more if it will chamber easily.

 

[Northernpiker]

^^^^ I agree, I don’t FL new brass (but you can if you want) it’s usually a minimum size, I do run a neck mandrel to straighten out the neck. After that I always FL and bump the neck back a couple thousands.