223AI forming dilemma...

[Roger M]

I have a 223AI with a .248 neck i need to prep brass for. While this isnt my first tight neck its my first AI. My worry is turning too much or too little of the neck. My initial thought was to use the cream of wheat method to form the cases then turn to the shoulder. I was setting up to form "false shoulders" for the fireforming then i thought why cant i do that and just turn the neck to the false shoulder? Then i can fully form with bullets and be done with it. To form the false shoulder i was expanding with a 6mm expander then sizing in a redding bushing die with the bushing adjusted to allow the bolt to close with some resistance. Any input would be great thanks

Roger

 

[DCRYDER]

If your forming from 223 brass there should be no false shoulders to make. Chamber should be reamed for a crush fit on existing shoulder.

 

[Roger M]

I do feel a small amount of resistance on the virgin brass. I guess more what i am trying to do is determine how much of the neck to turn if i want to neck turn before forming. My biggest fear i guess is some of the neck becoming part of the new shoulder resulting in a thin area. I dont want to ruin my pretty new brass. Im probably over thinking this. Just trying to do this the best way.

 

[fivering]

As stated earlier, the chamber should be cut a couple of thousandths short for a firm bolt closure against the shoulder.
I've been using this cartridge for several years and several thousand rounds, go ahead and turn your necks to the shoulder, load regular load and bullet and shoot. No need for all that cream of wheat, dacron filler and stuff like that.
Don't make a very simple process complicated.

 

[mackr]

With a 248 neck dimension you have no choice but to turn your outside necks down. I don't see how you could even chamber a piece of brass before turning some off the outside-forget about any false shoulder. Whoever chambered your barrel should have at the least made sure understood this, you have a very dangerous situation trying to put brass that is possibly 5-6 thou. too thick in the neck into this chamber. Find someone who can give you some hands on help. Be careful !!
Mack

 

[Ackman]

With a properly cut/headspaced chamber there's no need to mess with a false shoulder. Your .248" is a tight neck but not real tight. A light cut with the turner will be all that's needed. A loaded unturned caseneck will be around .248". Measure neck dia. with a seated bullet and turn to about .002" less. Don't mess with fillers, use bullets. Start at what's top end for a std .223 and go up from there. Find an accuracy load just like you would with any other cartridge and then use it. Think of them as working loads, not fireforming. You'll be going faster than a std. 223 and getting a perfectly formed case at the same time.