Rolling Shoulders

[bullet man]

Easy fix too much neck tension get a Lyman m die put a flare on the brass no more problem had a similar situation with 556 lc brass trying to load 75 match bullets put a flare on it saved the day. And the vld chamfer helps as well both together you should be good to go. You can get a universal flare die from lee it works just as well, but it's not cartridge specific like the Lyman.

 

[iceEworm]

I'm using a RCBS Gold Medal seating die. 300RUM ADG case and a 240gr Alco bullet. The first one went in without any trouble, than the next two did this. I've never seen this before, was wondering what the cause would be? Bullets have a coating of HbN.

View attachment 274224
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[Gcan]

I'm using a RCBS Gold Medal seating die. 300RUM ADG case and a 240gr Alco bullet. The first one went in without any trouble, than the next two did this. I've never seen this before, was wondering what the cause would be? Bullets have a coating of HbN.

View attachment 274224
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View attachment 274226
View attachment 274227

Chamfer Tool Controlled Depth Tapered Reamer, 6mm - .338

Reloading Chamfer Tool Controlled Depth Tapered Reamer, 6mm - .338, a newly designed handle with improved depth stop fingers for precise cutter depth control

kmshooting.com

best one money can buy

 

[iceEworm]

I had trouble with the Alco bullets also,they have a rebated boat tail and require a heavy chamfer. Mine did the same until I went HEAVY on the chamfer

 

[Wyowind]

Years ago I experienced the same problem with a .270 Wby cartridge. I was using new Norma brass and loading Swift bullets. Almost every case collapsed when I tried seating the bullets. Per the many comments already on here, I had full length sized the brass, chamfered the case mouth, had the dies adjusted properly, etc. Never having had that happen before, I was astonished and simply could not understand what was happening.

Long story short, I shifted to a Nosler Partition and the bullets seated just fine and I had zero case collapse. The Swift is a much stickier bullet than the Nosler Partition.

I also tried cleaning out the case mouths with a quick touch of steel wool, and then applied some dry case lube (mica) to the inside of the case necks. When I tried seating more Swift bullets after that preparation, they went in smoothly and easily with no more case collapse.

So the basic problem was too much friction/tension between the bullet and the inside of the case neck.

My problem could be solved by using an expander mandrel to open up the case mouth diameter to just the right size, or by switching to a more slippery bullet, or by taking steps to reduce the friction between the inside of the neck and the bullet surface.

YMMV.

- Wyowind

 

[idcwby]

Check this bushing on your sie and make sure it moves freely. The seating stem should pass through it without a round in it. Same issue I had and that bushing was sticking to the wall of the die. Cleaned it and put gun lube on it everytime I use itView attachment 274307

The bushing is loose. I learned my lesson on that one along time ago. I was holding the bushing up on that one to verify that wasn't the issue again. I know you can't see it in the pictures, but the collapse looks to be happening below the shoulder because you can still see some of the shoulder impression.

 

[idcwby]

What is the neck thickness of your brass? And what is the OD of your necks?

Busy moving cows today, so I'll try to get stuff measured tomorrow.

 

[camodave7]

What was your I.D. on the neck? Picture looks like you did not chamfer the neck, maybe you did. I had a similar problem with 5.56 rounds. They had very slight rolled shoulders, and I did not catch it until after several rounds. VLD chamfer tool helps also. I have never worked with ALCO bullets, so it could be something else.

Yep

 

[idcwby]

Thanks for all the replies. I'm thinking it's neck tension from all information provided here. Get some more measurements tomorrow, to answer some of the questions. All cases were chamfered with a VLD style.

 

[baggy270]

Die is set too low. Raise it up.

 

[The Oregonian]

Die is set too low. Raise it up.

He addressed that about 3 pages ago.

 

[Barkbuster20]

Definitely neck tension. I had the same thing happen when I thought I would make a 30-338 dummy round by just seating a boat tail .308 bullet into a 7mm rem mag case

Also 99% chance that goes away with sizing first and a proper chamfer

 

[338 dude]

I use a Lyman 22* chamfer tool, it's the "VLD" style like a K&M or Sinclairs (meaning 22* and not 45*), but a lot cheaper. Mine is in a RCBS prep station, not in the handle anymore.

Chamfer Reamer VLD (Very Low Drag)

Chamfer Reamer VLD (Very Low Drag) by LYMAN Lyman's VLD Chamfer/ Reamer eliminates damage to bullets caused by the sharp edges of the cartridge case neck. The long boat tail on VLD bullets are cut by the case mouth when chamfered with a standard 45 degree reamer. The sharp 22 degrees on the...

www.midsouthshooterssupply.com

FWIW I brush necks after I chamfer/deburr with an old RSBC case neck brush mounted on the prep station, it started as white nylon and is black now because I use an Imperial dry neck lube kit, so it probably has picked up enough graphite out of dirty necks to be the equivalent of dipping the case at this point.

Completely random aside for people who use the Imperial dry neck lube - do you dip the case or the bullet?

Case

 

[StoneyBurk]

What was your I.D. on the neck? Picture looks like you did not chamfer the neck, maybe you did. I had a similar problem with 5.56 rounds. They had very slight rolled shoulders, and I did not catch it until after several rounds. VLD chamfer tool helps also. I have never worked with ALCO bullets, so it could be something else.

I ve seen that happen on tight necks ! Try lubing the inside of the case and also chamfer the inside of the case neck