12g brass cartridge length trimming

[Anvil]

Hello all,

I'm making up some dummy 12g cartridges from unprimed Magtech brass cases, and I need to trim them down to the length of a loaded 2 1/2 inch cartridge (e.g. not including the crimped portion). I think that's about 52mm or 2 1/16 inches but if anyone has a better idea let me know - I'm working 300 miles away from my gun cabinet. 

Does anyone have a tip for trimming? I know there's the Gaep case trimmer, but I would have thought that wouldn't work on the rather thick brass. I've tried a pipe cutter, but it tends to crimp the brass in and it's not great at cutting a dead straight line. I'd be very happy to hear any tips any of you might have before I wreck a whole load of expensive cases. 

P.S. if anyone wants to sell some used Magtech 12g cases cheap I'd be happy to buy them, I don't know if they reach the end of a re-loadable life but as I just want them for the aesthetic, that's not a problem. 

Thanks in advance.

[TIGHTCHOKE]

Can you make a wooden dowel to fit inside the empty tube and keep its shape and size while you cut them down with a pipe slice?

[Anvil]

22 minutes ago, TIGHTCHOKE said:

Can you make a wooden dowel to fit inside the empty tube and keep its shape and size while you cut them down with a pipe slice?

That was my first thought, but the case crimps down onto the dowel like grim death and it's almost impossible to remove - not to mention the difficulty of keeping the pipe cutter aligned. 

https://www.amazon.co.uk/Preciva-Cutter-3-22mm-Aluminum-Cutting/dp/B073TZCZXC

That's the sort of cutter.

[Jaymo]

Your possible over tightening the cutter- it’s a multi sized plumbers cutter and they aren’t exactly designed for super clean cuts ( hence why plumbers have a De-burring tool)

Make it easy for yourself and use a thin cutting disc on an angle grinder , finish off with a file if out of ‘true’ 

 

Edited August 8, 2019 by Jaymo

[Anvil]

5 minutes ago, Jaymo said:

Your possible over tightening the cutter- it’s a multi sized plumbers cutter and they aren’t exactly designed for super clean cuts ( hence why plumbers have a De-burring tool)

Make it easy for yourself and use a thin cutting disc on an angle grinder , finish off with a file if out of ‘true’ 

 

You're probably right - these cases are very thin and very soft, so tend to form more than they cut. I think if I had a harder mandrel, something like delrin or copper, it'd work better.

However, as is usual when you tell someone your problems, I think I've found the solution. I'll make a tube of the right outside diameter and length, and that way I can use a fine sawblade to cut them down. I'm afraid the angle grinder idea might be overkill in a London flat! Does anyone know if I'm right as to length before I go mutilating 50 of them?

[Jaymo]

Never overkill 🙂, use mine for all sorts ........

[saddler]

Make a hollow jig or mandrel to hold them
Cut to length in a lathe

[figgy]

Make a straight cutter for a hacksaw, used to cut pipes.

Or what I would do is use a wraparound. But of straight card or plastic. Wrap around the case at your mark, wrap it twice around adjust it so it's tight and all lined up. Mark with a marker, cut with saw or disc cutter dremmmel or grinder with slitting disc.