Fire forming 223 Ackley Improved

[rkohles]

I am converting an 1885 Winchester/Browning Highwall from .223 Remington to a .223 Ackley Improved. Since the case headspaces on the shoulder, do I need to fire form the cases by seating the bullet into the lands to hold the case back? If I do, how many grains should the powder be reduced to keep from excess pressure?
Thanks all
Dick

 

[Rustystud]

Have you tried to load your bullets seated deeply into the rifling using the jam to hold the case back against the breech. Put just enough neck tension on them that the will soft seat. Wipe the case with a light coat of 20wt oil so the case push back against the breach shoot about 85% loads. They should fire form nicely. The other alternative is get a Hydrolic form die made. Hornady or any custm die maker can make them.
Nat Lambeth

 

[Preacher]

If the chamber was cut correctly you will have a bit of crush fit when you close it on a loaded round.
Loading into the lands will help out if the chamber is a bit long....
A grain or 2 under a max standard load for the .223 would be a good place to start.
If the cases don't 100% form on the first try add a bit more powder until they form good...

 

[Ackman]

To get a chamber that's right you'll want to at least set the barrel back one thread. A new case headspaces on the neck/shoulder junction. You'll want to feel some pressure - 'crush' - closing the action. It's the case sealing tight against the chamber in front and pushing hard against the action in back. Seating a bullet into the lands accomplishes nothing, lubing the case also accomplishes nothing. And think about this: The AI chamber is larger than a std. .223 chamber. Your .223 load is X amount of powder and the formed AI case holds a couple gr. more, so why on earth be fireforming with only 85% of your regular .223 load? Some of the advice people give out so freely about this stuff is just nonsense. When fireforming, start with your .223 load and go up from there, stop when you find best accuracy.

For instance.....the load in one .223 is 25.5gr/2015/50TNT = 3630fps. Fireforming load in a .223AI with tighter chamber is 26.5/2015/50TNT and velocity is a nicely accurate 3700-3725fps. I've shot whole gobs of varmints with this load and each case was perfectly formed.

 

[rkohles]

Thanks for the information gentlemen. It is much appreciated.
Dick