Crimping small calibre rounds and maybe large ones too -

[Gspragge]

Use a copper pipe cutter, remove the cutting disc and put in a suitable washer (hopefully better than
the manky one I used) add a spacer if it's a sloppy fit and ensure it is not too tight a fit and not be able to rotate.
Clamp the round together end to end to keep it tight into the case and not able to shift or move about. A large
wooden clamp is best. Slowly rotate the cutter as in cutting a copper pipe and after several rotations slowly tighen the clamp and it will crimp the case nicely
to suite. Rounding the egde of the washer will likely make a better job of it. I didn't have a brass washer to try, but that may
also give a good result. The bigger the pipe cutter the bigger the round that might be crimped. My round was a 20mm ~
It may be possible to place individual crimp indents using a larger tool and some care, I suspect a cleaner result than a mallet and flat screw driver
if one is carefull.
(I realize that in most cases one wants to be able to remove the projectile from the case and recrimping isn't an aid to that. But here I had two unused cases that had
never had projectiles in them and after fitting in the projectiles they wouldn't stay put so I had to figure out how to crimp them in place. )

 

[tigbrand]

That's a cracking idea Gordon, You can get bigger cutters for galve pipe so even bigger cases could be done. Just want to anneal the neck first.