Getting ready to fireform some 28 Sherman Mag….

[nksmfamjp]

I used a false shoulder, but I had misfires in 6PPC, so I'm worried a bit about that. I think I will jam the bullet and be very careful with primer crush when seating. I'm using ADG 28 Sherman Mag brass, but it looks like 300 PRC.

Any suggestions about how light of a powder charge. I plan to use quickload and put in the muzzle pressure factor for jam. I'm using 28 Nosler case capacities, but probably need to look at that a bit more.

For now, I'm thinking maybe 20% under max QL pressure with 0.5gr increments up and look for when I hit max cbtd and then load just a bit over that. Any other opinions? I hate putting bullets in the throat with so much powder, but this has proven safe before in other rounds.

 

[twister]

you should not have to jam the bullets. when you neck it down just size until it just chambers and you will be good to go with a 10% reduced charge.

The SM series will need the shoulder blown out to 40 degrees so loads should be decreased by 8-10% for the initial firing.
The future plan is to add to the tooling now available to create fully formed brass in the next few years.
For bore sizes other than head stamped, the bullet may need to be jammed for the initial reduced load firing.

28SM

- brass will have a .308 neck and will need to be necked down