I need to fire-form some brass that is presently short on headspace. I intend to create an artificial headspace in order to ignite the round by running the bullet out to contact the lands.
My question is, since I have heard that reduced loads create, in some cases, more pressure than full charges, should I perform this proceedure with full powder charges? If I were to do this with a reduced load, how reduced? one-half charge? one-quarter?
A much better and cheaper method to fireform is to use your false shoulder but use a fast pistol powder, Cream O'Wheat or cornmeal as a filler, and a wad of toilet paper as a "bullet".
AI cases are usually factory brass fired in the chamber with a full load. That load is "reduced" because of the larger volume of the chamber. When fireforming with bullets I usually reduce the load from a max load, by 10%.
Posts: 1261 | Location: Placerville, CA, US of A | Registered: 07 January 2001
quote:Originally posted by GAHUNTER: I need to fire-form some brass that is presently short on headspace. I intend to create an artificial headspace in order to ignite the round by running the bullet out to contact the lands.
My question is, since I have heard that reduced loads create, in some cases, more pressure than full charges, should I perform this proceedure with full powder charges? If I were to do this with a reduced load, how reduced? one-half charge? one-quarter?
How do you guys fire-form "improved" calibers?
I use a 10% reduced starting charge of which ever powder that works in the cartridge that I have the most of or didn't work as well as I wanted.....I use a long seated into the lands firm bullet...again a less than good performer or heavy/long for caliber bullet.....a true improved caliber should have the same headspace and thus isn't difficult to fireform as some caliber changes and moving the shoulder a bunch....after fireforming the first time I like to shoot them again at a starting load with long seated bullet to get a good form and prepare the brass for detailing for accuracy or hunting loading....good luck and good shooting!!!
Posts: 687 | Location: Jackson/Tenn/Madison | Registered: 07 March 2001
GA Fireforming cases by seating the bullet out far enough to positively engage the rifling is the best way of forming cases in MY opinion. I would suggest you use a recommended start load for the std caliber and bullet weight you are using.I would load only 1 or 2 rounds and go to the range and fire them. Ensure there is sufficient pressure to completely form the case.If the shoulder is not formed clearly and sharp load 1 or 2 grs more powder and try again.Once you have arrived at a load that forms the cases nicely mark it down. I would also recommend using a medium speed powder such as 4895. Stay away from real slow burning powder for fireforming.
The thing about fireforming is that it is purty near impossible to not stretch the case. Even with fals shoulders on the brass, and with bullets into the lands.
With 25 lbs of pressure from the firing spring, it's very hard to keep brass from bending, or bullets from engraving!
I've gone to seating bullets backwards (flatbase forward) and using normal powder charges, aiming for an estimated 45,000 psi or so. That seems to be the point where you get sharp corners and such. The flat base is harder for the firing pin to engrave than a 5 or 6 caliber ogive. It seems to keep the case from moving forward upon firing pin impact. JMO, Dutch.
Posts: 4564 | Location: Idaho Falls, ID, USA | Registered: 21 September 2000
