I just finished building my first complete custom bench rifle and am just starting to fire form cases. I was wondering if anyone on this site or anyone of the more experienced bench shooters here have written down a good procedure on how to start working the right load that works the best in my rifle. With all the different weight bullets, different powders and all the variables such as bullet neck pressures, distance from the lands, + a grain
- a grain. How is a person to start working through all these?
Thanks in advance for any help. I chambered my rifle in 7 mm WSM AI.
kraayenb

THANKS!! guys Looks like I have a lot of work to do ! One more question, When you fire form cases to AI are the cases fully formed after the first fireing or will they change some each time they get fired? I know I need to continually check case length and I plan to neck size only after forming.

it depends on the composition of the brass.
i generally have better results with remington brass in my ackleys.
i like to use a false shoulder on the neck for the first firing.

A true "AI" chamber, as in Ackley Improved will allow you to fireform your brass from standard factory ammunition. Just chamber a round and fire. That was part and parcel to P.O. Ackley's design at the outset.

The term "AI" gets over used and abused these days in my opinion, as every "improved" shape it seems is called "AI".

If I'm loading fresh virgin brass for my 257 Ackley Roberts, I load a mid range load, and I seat the bullet so that when it is chambered, it is jammed into the rifling. I don't use fired standard brass to fireform into AI brass, only virgin brass.

Once the brass is fireformed, it grows in length very little after the initial firing. One of the benefits of the AI design, less brass flowing forwards due to reduced taper in the case. You still have to check your brass length, sure, but don't expect it to grow much.

Lamar: I am not sure what a false shoulder is?
slowpoke slim: I am starting with virgin brass but Winchester. I also started with a smaller bullet 130gr Sierra Match King HPBT and the minimum powder listed in there book at 63gr because I have incorporated a few new design elements in my build that are basically experimental and untested and I needed to verify that my designs were safe and functional. I am pleased to find out after the first 25 rounds everything preformed flawlessly and I am now ready to reload for accuracy.
Thanks all for the input !!!
Bill