I am loading some 250 Sav brass for fireforming into the Ack Imp version and was wondering if H380 would be suitable, I'm loading about 3/4th of the way up the scale towards Max as I usually do with my other powder but have never used H380 for this before. I would go buy more of my regular powder but the Air Force is transferring us very shortly and can't ship powder in Household Goods and carrying it on the plane in baggage is sure a no-no. I'm also using a 120 gr bullet. Any ideas?

Steve E.......

Try 37 to 38 gr. H380 behind a 90 gr. bullet. roger

There seem to be two achools of thought on fireforming. The most well known procedure is to load a relatively fast powder to 90 percent of maximum and seat a long bullet into the lands to support the case as it is being fired and blown out.

An off shoot of the above procedure that also works well is forming a preliminary shoulder by necking a case up and then back down to head space the unformed case on.

The most recent development pretty much follows the first proceedure but uses as much of the slowest powder you can use to fire form. The advantage of using this compressed load technique is that the firing pin strike can't drive the case forward, which can still happen with the preliminary shoulder and standard fireforming techniques, because the bullet is seated into the lands and the compressed powder load wont allow the firing pin strike to drive the case forward. The firing pin strike can drive a case forward on a bullet seated into the lands if there is nothing else to support the case, shortening brass life considerably because the web area is worked too much and case seperation will eventually happen, especially if your die adjustments aren't right on. That's why AI improved cases should be chambered a few thousandths shorter than the parent cartridge but most smiths don't chamber them that way. The slow powder method covers your bases no matter how the chamber work was done...Rusty.

Thanks for the info, I was wondering if H380 was a good powder to fireform with. The way I cut my chambers is to have a slight crush fit on sized 'standard' virgin brass and when loading fireforming loads I usually seat the bullets snug with the riflings. Don't know if that helps against the firing pin driving the case forward in the real world or not but it does help in my mind. All this and the 120 gr. bullets has resulted in cases being formed correctly the first firing or at least it has so far. Now that I have said that my next cases will probably come out looking like Weatherby cases. LOL

Steve E..........

As your case is a crush fit (as it's supposed to be), any standard load (factory or handload) will form with no other messing around needed.

Dear Steve,
I would use about 7.0 grs of Bullseye and a cheap bullet. I make ALL my brass for the 250 AI from Lake City N.M. brass. I make it into standard 250 Sav first and then fireform to the AI with the above load. No loss and the cases last darn near forever. I still have a box I made up in Hawaii that I use to this day and that was 14 yrs ago and that many seasons.

Aloha, Mark

quote:

That's why AI improved cases should be chambered a few thousandths shorter than the parent cartridge but most smiths don't chamber them that way. The slow powder method covers your bases no matter how the chamber work was done...Rusty.

Rusty, I gotta disagree with you on this one! All "gunsmiths" chamber correctly when it comes to Ackley cartridges or whatever improved cartridge you would care to discuss. Gunplumbers chamber to close tolerances but "gunsmiths" chamber to correct tolerances. If your cartridge moves forward when the pin falls you have employed a plumber and not a smith.

Steve, Put a max load under the bullet of your choice and have a ball. Jim