I just bought a .300 WSM, and have started reloading for it. I bought RCBS .300 WSM dies, and use virgin Winchester brass. I full length resize the brass, chamfer it, then prime it. After dropping the appropriate load of H4350 powder, I use the RCBS seating die to seat the bullet to the recommended OAL. Here's my problem: Once the bullets are seated, the shoulders of the cartridges bulge, and won't feed into the chamber. There's no problem feeding into the chamber after full length resizing, only after the bullet is seated. I measured the shoulders both pre and post seating, and the shoulders expand by .015 after bullet seating. HELP!!!!!

Your seater is likely adjusted a tad too deeply into the press. Unscrew it a couple of turns, and see if that helps. You can achieve the bullet seating depth you are after by adjusting the bullet seating stem.

- mike

+1 your die is screwed into your press to far.... back it of a good bit then readjust your stem.

Also add trimming your brass to your regimine.

The others have got it pegged, the crimp ring in the die is contacting the case as the bullet is seated.
The easiest way I`ve found to set your seater is to place a empty case in the shellholder, and with the ram raised, screw the die until it makes contact with the case. You will feel it, there is no mistaking contact. Now back it out a turn and lock the ring. Make all OAL adjustments with the seating stem, then lock it when proper depth is reached.
If a crimp is needed, after the seating adjustments are made, back the seating stem out a couple turns and with the lock ring loosened screw the die body deeper in very small increments with the cartridge still in the shellholder, until the desired crimp is formed. Relock the body lockring, and screw the seating stem down until contact is made with the bullet and lock it in place.

Thanks, guys. Problem solved.

I use a five cent nickel on top the shellholder for all my seating dies....it's about right.

quote:

Originally posted by ray in seattle:
I use a five cent nickel on top the shellholder for all my seating dies....it's about right.

+1

Don

I would bullet seat then crimp in two separate operations as mentioned in the previous posts.

If you want a crimp I would us a separate die.
Specifically a Lee Factory Crimp die.

It does the best type of crimp and prevents you from applying too much roll type crimp which can loosen the cases grip on the bullet.

It also prevents shoulder bulge like you have already experienced and you don't have to mess up your carefully adjusted bullet seating die.

quote:

Originally posted by ray in seattle:
I use a five cent nickel on top the shellholder for all my seating dies....it's about right.

I'm all of it 5 cent nickels, can I use a 6 cent one?