Getting Ackley Brass Right

[Coltdriver]

If you form and tweak any AI brass I would sure appreciate your comments.

I got some 243 Lapua brass, formed it with a blank charge, reamed the necks, then loaded up some 87 grain Noslers and got outstanding results.

When the brass formed there is a little donut around the neck right at the shoulder to neck junction.

Do you trim this off with a neck trimmer??

How close to the neck shoulder junction do you trim to?

Thanks!

 

[fguffey]

Coltdriver, I hear a lot about a 'do-nut', sometimes the donut is inside the neck at the shoulder, I can make those, the other do-nut is outside the neck at the shoulder, that one I know how to avoid, the Ackley Improved, any Ackley improved has a longer neck than original chamber, when chamber is reamed to an Ackley Improved chamber the barrel must be moved back to remove all of the original chamber, in the case of the 30/06 Springfield and the 30/06 Ackley Improved the neck on the 30/06 Springfield is .031 shorter than the 30/06 Ackley Improved, if not chambered correctly, the .031 thousands will appear as a collar on the formed case and is caused by part of the original chamber not being removed, I like the Gibbs chambers, in the case of the 30/06 the shoulder is moved forward .113.

The other collar, inside the neck at the shoulder is caused by brass not being able to flow around shoulder neck junction, this is not a problem when working brass with the 17 degree 30' shoulder or cases like the 30/40 Krag, 300 H&H, and 303 British.

You will hear about resistance to chambering when commercial ammo is chambered in an Ackley Improved chamber, the resistance is caused by it's short neck being chambered in the long neck of the Ackley, so the neck formed of the neck is formed when chambered and the rest of the case/shoulder is formed when the case if fired.

F. Guffey

 

[fguffey]

neck is formed when the case is chambered

F. Guffey

 

[Coltdriver]

Thanks for the reply fguffy.

So when I had this barrel re chambered it was removed and set back a full turn.

Do you suppose that if I fire formed the cases with a blank charge that I could get the same effect (forming the donut)? I can almost imagine the case shoulder blowing out to fill in the Ackley shoulder profile but the neck starting to expand then forming that donut and stopping.

Maybe I should fire form the cases using a regular bullet and a regular charge.

When I have fired factory ammo I do not get the neck donut. Just with these Lapua which were only formed with some blue dot initially.

 

[fguffey]

Coltdriver, I do not use reduced loads, I do it once, there is a cushion, the case must fill the chamber forward and out before pressure can build, if time is a factor, I worry about an obstruction created by the filler, oatmeal, paper etc., I just do not do it, as I said, I fire form cases once.

Because most of my fire forming is with Improved/Modified chambers, some cases shorten instead of lengthen, so blow out the case does not mean the case blows forward, if you measure the case before and after, there are times when the neck pulls back when the case blows out and fills the chamber.

Give the process a chance, use new cases (loaded ammo) and avoid reduced loads, this process increases the chance of success.

F. Guffey

 

[rundm]

K and N makes a carbide neck turner that will remove however much of the neck you want too. you can trim up the outside of the necks although the Lapua really never needs this unless it is a tight necked gun. when you turn the outside of the necks you can just touch the neck shoulder junction and remove just enough of what you want to. takes a few minutes per case but you do not have to do it again in most cases. the ackley cartridge is much less prone to streching and such like that so as long as you do not over pressure the cases, they should resize very easily. On my ackley I used to neck size only for the first few firings and then I would full length size every 3rd or 4th time. makes the brass last a lot longer also. load those suckers up with real bullets and go shoot them. do not go light on the loads because you want to make sure you form the cases right. if you do not give it a good load, you will not form the cases all the way and this is probably causing your problems. the factory loads are generally pretty stiff now. generally when shooting fire forming loads the ackleys are usually pretty accurate. RG