I bought some 338/378 brass at the right price new ,to fireform to 378 ,should I anneal it first, then fireform ? or Anneal before and after ?
Some years ago I got some very old 378 brass and the necks split around the neck ,to the point a lot of the necks came completely off and exited the barrel.
I would like to try to get the best life I can out of this brass as its getting more expensive and harder to get ,
cheers thanks for any tips

I would neck the brass up in 2 steps. From 338 to 358 in step 1 and 358 to 375 in step 2..Lube the inside of the case necks before expanding. I would then anneal load and fire.Treat them like any other 1-fired brass from there.

The change is not that great, I think one pass should work.

Plenty of lube, and SLOWLY!

I neck up 223 brass to 308 in one pass.

I haven’t lost ant cases, though others here seem to crack the neck sometimes.

Oh, I had to read it correctly (I think)

You have 338.378 brass and want to neck it UP.

Ya, I'd anneal first.



Zeke

Will add another comment. Had a friend necking up 300 Wby cases to 340. He started by annealing the first box of brass and had the radius shoulder collapse when necking them up.Lost 4 or 5 cases out of 20. Yes he lubed the necks. He asked for my advice and I suggested we try another box and lube the cases neck up then anneal. He never lost a case with that method . You guess which method he uses now

Thanks for the info ,i was using cream of wheat to fireform them, and wondered should i anneal before or after doing that

From 338/378 WBY to 378 WBY

quote:

Originally posted by Robertcat:
Thanks for the info ,i was using cream of wheat to fireform them, and wondered should i anneal before or after doing that

We never use cream of wheat.

We use bullets seated into the rifling.

Cases form perfectly.

Use a bunch of fast powder and seal neck with wax.