Trimming down 4590 cases to 4570

[Trailboss]

I just bought a stack of secondhand 4570 brass that I intend using in my 1895. I normally shoot a soft 405 grain cast Bullet .....I noticed after measuring that there is dozens of 4590 Brass in the bag. It’s all stamped 4570 govt RP ......can I just trim the longer cases down and use them in my 1895 marlin? Or am I better off just selling them to a 4590 enthusiast? .......nb....there is no hornady Flex tip short cases in the batch it’s all proper 4570 length Or proper 4590 length .......I was going to set up a jig to dock them with a thin mini disc in a grinder and then use proper case trimming equipment to deal with the last mm accurately, and properly

[sharps4590]

Being a 45-90 aficionado I'd like to see you sell or swap them to a -90 shooter if they're assuredly 2.4 in. Sometimes that brass is hard to find. If not then yes, they should trim to 2.1 just fine.

[JimB..]

Factory marked 45/70 that’s 2.4” long. That’s unusual.

[Trailboss]

Yes unusual, it’s almost as if they couldn’t be bothered to change the head stamp during manufacturing.....I don’t know how they make cases. They def are 2.4 inch long And I have oodles of 4570 cases so I don’t need any more. Much better I think to move them on to a good home. Somewhere, some time there will be somebody looking for some. In Australia new cases are 2-3 dollars per case. I’ll probably just offer these at a dollar a case

[JimB..]

Yes unusual, it’s almost as if they couldn’t be bothered to change the head stamp during manufacturing.....I don’t know how they make cases. They def are 2.4 inch long And I have oodles of 4570 cases so I don’t need any more. Much better I think to move them on to a good home. Somewhere, some time there will be somebody looking for some. In Australia new cases are 2-3 dollars per case. I’ll probably just offer these at a dollar a case
Just for grins, would you weigh 10 of them and compare to the weight of 10 45/70 cases with the same headstamp?

[country gent]

I believe at one time BACo and some others stretched 45-70 to the 45-90s 2.4 length. using heavy hydraulic presses. Hence the 45-70 head space wouldnt have changed. Starline now makes 5-90 with correct head stamp.

Weigh several of each case f they are close to the same weight they may be stretched brass

[MostlyLeverGuns]

I think country gent is probably right, there are techniques for stretching brass, with the 45-70 head stamp, my guess would be stretched. Some of the cartridges conversion books mention stretching or detail how to stretch brass.

[Trailboss]

I ended up just selling the cases to a 4590 user.......I told him about the headstamp and he understands that at some stage they were stretched or spun or whatever to lake them longer and he understands it’s sensible or essential to load them reduced for safety. So all good in the ind.