Ok so it's not really a new cartridge, it's just a severely downloaded .270win.
So I've got a .300 winmag for real serious targets and didn't want to put in the time to find a cast load for it when I already have a copper load doing over 3100fps shooting 1/2" @100yds. I already had some .270 dies and "needed" a gun to go with those dies. So I traded a Marlin .22 bolt action for a Savage 111 in .270.
I'm using Lee's 135gr .277" as cast and unchecked. My alloy is 3:1 WW:salvaged plumbing lead. I settled on this alloy when I was shooting SASS. It worked equally well for my .45Colt BP loads as it did for my 1400fps hunting loads. And if I keep everything the same I don't have to remember which is which!!
So, I have 2 loads, both of which are well below anything in a load manual. First, is 7gr of Unique under the 135 for 1150fps. Because Unique in large cases is position sensitive, I bought some Trail Boss to try. I started at 11gr and worked my way down. The best load I found with the TB was also 7gr. But the TB chrono'ed @ 1075fps. From the data I've looked at, this bullet at this velocity has about 50 more ft/lbs of energy than a .22Mag. It is nice to be able to to shoot the .270 without needing ear protection too.
I haven't recovered any game yet. Got some Muskrats in a farm pond that I've been looking for but haven't seen them when I had the .270 with me. I have shot at some turtles that have infested the pond but they don't come back up. I don't know if I'm hitting them and they are sinking or if I'm missing them and they are staying under. It's quite a challenge to hit a turtle's head from 50yds and the splashes are really impressive. I'm also hoping to call in a coyote for test media. No luck there yet either. I'll let you know when I have more "data".
CS