Forming 243 40' Improved

[Rev]

I agree with everything stated above. Use a moderate to full standard .243 W load of medium burning rate powder (4895, 4064, 4320. 748 or whatever you have most of near those burning rates.

In my 6mm. AI, I use new un-annealed brass (usually Rem.) and 95-100 gr. bullets. I do seat the bullets firmly into the lands when fire forming. That insures that the head stamp of the case is firmly against the bolt face and any stretching is forward as the fire forming takes place. Pressing the bullet into the lands also will increase initial chamber pressure slightly (but not dangerously) helping to fire form the case the first time. I also like to feel slight resistance when closing the bolt.

After fire forming, I like to neck size only for as long as possible. When chambering becomes more difficult after several (sometimes numerous) reloadings, I'll partially resize the case body just enough for easy chambering. With the 40 degree shoulder, my case lengths hardly grow at all.

I know I've repeated a lot of what's already been said, but just wanted to throw in another opinion agreeing with all the others.

BTW, IMR-4350, Nosler 95 gr. BT's, and Fed 210M's with Rem cases work best in my 6mm. AI.

Rev