Re: 243 Ackley Improved Problems
When you say it Wont close, will it close but with some resistence? If this is the case and the chamber isnt a tight neck this is normal. With Improved cartridges there is always some resistence when chambering unformed brass, this is providing your headspace until fireformed. If it closes with some force look at the brass and you should see a ring at the neck shoulder junction and it should chamber easier if you try it again. There are other issues like neck diameter that it could be but I would make sure that this doesnt work first. If it doesnt work, Then you would have to find out if you need to neck turn your brass or trim to fit.
I dont know of any formed brass and it really wouldnt help you anyway.
BTW: If the bolt closed easily in the chamber with a standard .243 you would have more to worry about.