Anyone with Small Base Die Issues?

[DaveB]

I have a 308 semi-auto that is having trouble with brass that has been through a small base sizing die (RCBS).

I cannot this moment check the shoulder angle but would swear it is set back too far.

We have used the same 308 SB dies in our bolt 308 with zero issues and again, very good accuracy.

The semi-auto 308 shoots factory junk ammo extremely well. My stuff has all kinds of trouble-mostly FTF.

I believe the shoulder is set back so far the brass is in contact with the lands. There are marks on the brass that certainly look that way-equal spacing for one.

Has anyone observed similar issues?

Note:
I have used SB dies in my 223 world forever with no issues and hyper good accuracy.

 

[Remi]

Sounds like you have the die adjusted to size too much creating excess headspace and causing ftf . If the chamber on your semi is larger than on the bolt gun brass sized to work in one may not work in another. I had two 30-06's and the difference in chamber size was enough that brass had to be kept separate because one was much larger and I was over sizing brass based off the smaller chamber.

How much shoulder bump are you getting?


Ive never used small base dies in anything. Was there a need or was that your preference?

 

[TiminTN]

Has to be excessive headspace in the semi auto.

 

[DaveB]

We returned the rifle and damaged brass to the manufacturer who sent it back after some adjustments. We also went through a pretty detailed adjustment session with the FL sizing die.

The 308 bolt would take the same round that had marks on the brass no problem at all. So we had this issue where the bolt action would function properly and the semi auto exhibited damage to the brass on the same cartridge. The factory adjustments and the die adjustments brought the semi-auto back into full functionality with no damaged brass whether we shot factory ammo or hand loads.

The very good news is we have not sacrificed accuracy.