Fireforming brass

[RevJim]

 In fireforming Ackley Improved brass, I always used a warm charge of medium rate powder (i.e. 4350,etc) and a long bullet seated into the lands. I did this for my 35 WAI, a .375 Weatherby, .280 AI, among others and a 338/280 I tried once, also a 30-30 AI. I did try to form some of the 338/280 brass with half a case of pistol powder and a cottonball tamped on it.  I had trouble with the nickel plated brass I had for the .280; flaked nickel, split necks, then just went back to the bullet method.
 Yesterday I tried something new (for me) I took some new and old Remington 35 Whelen brass, primed with rifle primers, dropped 15gr of Blue dot ( Lee dipper) tamped a 1/4 sheet of tp on it, filled the case up to about 1/8 of the top with cornmeal, plugged with wax. I ended up with perfectly formed brass, no losses. It was also fun to do!
 I had also used my regular Hornady 35 Whelen FL dies (elliptical expanding ball model) to neck up some new Nosler 30.06 brass to .35; I just lubed them a little with Imperial sizing wax .I had the die set up to not quite size the neck to the shoulder, leaving an "ever so slight" bulge at neck/shoulder junction. This made for a slight crush fit when chambering. I was searching for .358 win velocities using some Remington 200 PSP bullets and H4895. I started at 43 gr and ended with 47 being the best accuracy ( around 1.25 or so) I did not have my chrono set up, too many people at the range! I had seated the bullets out just a little below the cannelure and crimped them with a Lee Factory Crimp die. Point being, my brass came out perfect with this method too. Happy.

[crash87]

On my 257 Roberts A.I. I used the neck it up, then down, false shoulder method, and of course using a starting load of some medium powder, it foreformed them perfectly. The down side to this method is large amounts of powder is being used and bullets are sent down range basically to just form a case. If your in prairie dog country, I'm not, the matter is different.
Upon getting a 223Rem rechambered to a A.I. I didn't want to use up my, now precious, (Thanks to the current middle class American hating administration) components. 10 gr of bullseye, with Cream of wheat to 1/2 way up the neck. Then a piece of balled up tissue paper, in lieu of wax, pressed down to compress. Perfect formed case. And saving myself a bullet to be used for load development and then a mangy coyote. Also, a pound of bullseye goes a long way.
It is also rather quick and easy to do in volume, Set up to dump 10 gr. of bullseye, then set it up to dump the required amount of c.o.w., "volume reloading for fireforming". crash87

[RevJim]

 My very first Improved cartridge was in Rem 700 Classic .257 Roberts, early '80s. The gunsmith who set it up did a jam up job too. It had enough crush fit with factory ammo that I just shot it for practice to get brass. I never lost a case with it! I seated out that long Hornady 120 HP and a case full of IMR4350, shot crows with it. sold it to a friend who killed lots of whitetails with it. It turned me into an Ackley Freak, ha. My next one was the .280 Ackley...thing looked like a rocket! It was done locally and didn't have enough crush fit, so I went to the bullet seated into the lands method. Its a good method, as said, if you want to practice or shoot prairie dogs, etc.