.250 Helldiver
Overall length of case 2.321
Overall length of cartridge 3.00
Case- 30-40 Krag left full length, neck to .25 cal
In a letter from Wallack dated July, 6th 1954, he states use of 48 grains of #4350 powder with 100 grain bullet. He further states it would be wise to start with a lesser charge of powder of about 46 grains and work up the load for best results.
Wallack mentions never having used any bullet in .25 cal under 100 grain weight and his having no use for any .25 caliber bullet under that weight.
Test fired four (4) 30-40 Krag cases necked down to .250 ****-diver and fired same in gun on 12/8/1956. Used forty eight (48) grains of #4350 powder with 100 grain weight Remington Core-Lokt bullet.
After test firing - cases extracted very easily for m chamber of gun and priers showed no flattening beyond normal found in use of 46 grains #4350 with 100 grain bullet. Indications are that use of 48 grains #4350 perfectly safe.
My disclaimer: Use of the above info is at your own risk!
Although I haven't shot my rifle in over 30 years, it was a hoot to shoot. My cousin and his friend have been working on fire forming cases and reloading some for me. I'm hoping they'll put there escapades in an article format as there is a lot of history to this caliber and rifle.