Hi I was thinking about a light short action in 270 something. Could someone tell me the basic idea behind making 270/257 imp. As in neck up first then fire form to improved or improve first then nesk up. That would require a 257 improved rifle also? Is it more trouble than it's worth, I could just go with a 270/308, (maybe improved)anyhow any imput into this procedure would help. When I get a better idea of how to form the cases I'll make up my mind. I'm stuck on 270 because it fill a nich in my battery.

Short action, 270 something? How about the 270WSM??

Well since the the 257 is based on the 7X57 go with it unless you really want something with a lot more power then go with the 270WSM. I can't imagine that the .277 could do anything the .284 couldn't do. In my opinion the 7x57 and 257 are best suited for a medium or long length action. There is also the 284Win. I know it is chambered in the short action but the bullet really eats powder space.

I have a 6.5/284, I was just trying to come up with something different, I thought about the 270/284 but was thinking I'd be able to fit another one in the mag sticking to slimmer cases. Probably go with the 270/308 for ease of everything. And I can't got with the 270 WSM, if I did that I could buy ammo, what fun is that?

Just for the sake of understanding let's call the round you want to end up with a .270x57mm IMP.Start wih an 8MMx57mm and neck it down. If you start with the 8mm you'll have enough shoulder to get good head space prior to fire forming.You can get complete or near complete form the first shot.It may come out a tad short but it will grow. You may or may not have to turn the necks. Probably not.After all is said and done you can go back to calling it a .270/.257 IMP---and it will be. roger

Have you thought of a 270 savage?

What I was really wondering is, say I am making 270/308 improved, do I size down 308 and fireform for improved or neck up 243 and fire form or do I have to start with improved cases before I neck size? I have a buddy with a 243 impoved so I could use brass from him if I had to. Any thoughts?

Start with a case that has a larger but, close caliber to start out with 708 or 308 will work. Its easier to size down ounce than size up to get a secondary shoulder then down to locate it for headspaceing. You may also split some necks sizeing 243 up to 270. I would also anneal the cases before forming. I wouldn't use improved brass to start out with unless I had to It may complicate reforming.

Personally I see that a 7X57 or 8X57 improved giving more increase than the 308. The 308/243 is pretty much improved already except for the shoulder.

But to each his own.

Since the differnce between .270 and 7mm's bullets is only 0.007. Why not go with a 7mm-08AI. That way you can simply use factory 7mm-08 rounds to fireform the AI shoulder. The 7mm-08AI route would be so much simpler and less fusy. But if you must have a .270 then a .270/.308 would be the second alternative.

C-ROY

270/308 Imp is called a 270 Redding. They already have the dies for you.

7X57mm AI! There is a much better selection of .284" bullets available than there are .277" bullets.

OK! We'll go one more. Wait a while and than Improve the new military .270. Eventually you'll be able to get a lot of cheap cases and it will be popular. Look what the military did for the ill designed.308. roger