257 Weatherby

I couldn't wait to fire my new rifle and the brass ordered hasn't arrived but the dies did so started thinking how to solve the problem. I have a lot of 300 Win. Mag. brass, so my first thought was to squeeze some down. This would be a lot of reduction and would require an intermediate die to step it down. I thought of various dies I have and remembered the 7mm mag dies, that would be a good step down. Then I remembered some 7mm brass I had scrounged. There were 16 cases in the box, and when compared to the 257 case the shoulders were even at the start, and the necks were close. I lubed one up and ran it into the 257 die, it went smooth as silk and didn't take a lot of pressure. It looked great but when I measured the length to see if I needed to trim they were .050 short. The 100gr. Sierra's would have at least .250 to the base of the neck, looked like a 300 Win. Mag with the short neck. I tried the case in the gun and had to run it through the sizer again to get it to go without hard camming of the bolt. I primed with win. LR mag primer and put a start load of 4831 in, then seated the bullet to the base of the neck. Test firing seemed mild in report and recoil. The case did't even havethe lube dent blown out, so this was a mild load. I then resized all 16 cases, rotating each case 180 degrees and sizing again. All worked through the action well. I next loaded 69 gr, of 7828ssc(my chosen powder for this round) in a case and 71 gr. in another. The 69 gr. load was noticably hotter than the first load and the case was nicely fire formed with no signs of pressure. I then fired the 71 gr. load, it was a little hotter by the recoil and report, but still no signs of excess pressure. I have loaded all 16 cases with 71 gr. and am waiting for weather and opportunity to permit bench testing to see where we go from here. 73 gr. is listed as max load, so I would like to stay at 71, but will let the gun tell me what it wants. I will be wanting to load some cast too, so am bidding on molds on Ebay. DALE