Sizing problems 300BLK

[Sig220]

I think it is a die adjustment problem most likely. If you get the sizing ball too low in the die it will bind with enough force to cause the rim to shear.
JMHO.

[TRshootem]

The trick to using One Shot is to apply liberally. It works fine but many apply too little and have the issue you describe. I loaded 250 .223 varmint loads in once fired IMI 5.56 brass yesterday, all sprayed with it. I used the spray because this was a small load session and easy to remove with a cloth as I load into ammo boxes. I, like so many others learned too little was not enough

One Shot is not exactly economical compared to other lubes, but can be left on the loaded ammo once dry if one wants to skip that step. Rifle cases larger than .223 or .22-250 surely do need being sprayed with more. At that point of cartridge size like .308 or larger, it's wise to use lanolin based spray or the greasy stuff of choice.

[treadwm]

That pic looks funny to me. Are you sure you're using the correct shellholder?

I thought the same thing. That is supposed to be correct but I'm ordering another RCBS one to be sure.

Wheres the decap pin? Is the expander ball too high?

I decap everything first with a dedicated decap die that doesn't ever jam. After the 5th time having to recover from a stuck case, I raised the expander a little at a time to see if that would help. It didn't

These are not new dies. I have reloaded prob a couple thousand rds thru them prior to this. In the past, they only stuck if I was stupid was ran them thru dirty or not lubed. Each time they've stuck, after removed the brass, I've cleaned them and relubed them w/ OneShot and let it dry. Till now that has worked well. Honestly, I'm looking hard at the shellholder. It isn't marked as clearly as I would like and the rims are being torn off much easier than I would expect. I have new shellholders and other lubes on order. When they come in, I'll report back on whether any of it made a difference.
Thanks everyone for chiming in. Much appreciated!

[treadwm]

For those of you that've been following along, I think I've solved the problem. And the silly answer is:

Bad shellholder!

Rummaged through my spare reloading crap and found another RCBS #10 shellholder. Popped it in and finished the batch that had been giving so much trouble. Tumbled another 100 or so and ran those through without a single problem.

Dunno what the problem was w/ the original. Didn't look damaged or worn but it's in the scrap metal bin now. Of course I found the spare shellholder AFTER I placed my order for a replacement. Oh well, now I'll have another spare and some other lubes to try out.
Thx, guys!