I did similar in .358 using .30MI Carbine brass, .375 using .223 ammo and .458's using .303 Brit and sized down .250 Savage brass. I left the spent primers in the brass. I annealed the cases.
A 9.5 mm (.375 groove dia.) rifle chamber should have a .365" bore diameter.
So with a bore riding bullet, the bullet needs to have a .365" nose and .375" to .377" outside diameter.
With bullet cast hard enough and coated to withstand 3,000fps, the alloy must be VERY hard & the coating a VERY good lubricant.