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[Rebel_Rider1969]

Several folks have tried to do a 357 bullet case, off of the 223/5.56 straight case. It is just a wee bit too small in diameter, when you add the bullet to the case. So those folks ended up with a 9mm and a shortened case in the AR.
This is one solution, using military brass, based on the 6.8 SPC case. The 358 MGP.
It does most of what a 358 Win needs to do in the SE woods. With 1680 and 180s it will do 2,700 fps in a 16" AR-15. Similar to what a rimless 357 Herrett in a rifle would be.
The TAC 30 and 358 MGP are based on the 6.8 the 300 BO on 223.
View attachment 508892

So the 357AR (max) using 357 bullets in unformed 223 brass might be problematic? Split case necks etc..

 

[capt.joe]

When I bought my barrel I didn't hear of split cases. But you do have to ream the inside of the case for the bullet.