I am toying around with the idea of suping up my MK II Sten and need some ideas on calibers.

My only requirements are that the conversion involve just a barrel change with out magazine modifications.

So far the calibers I have thought of are 30 luger, 22 TCM9R, and 32naa.

My only real concern with ones like 22TCM9R is that it has never been done to my knowledge and the gun is straight blowback and I imagine bolt velocity would be pretty high. I suppose a tungsten weight would have to be added to the bolt but I don't know.

If I did the other two I would be looking to load them to 9mm pressures for the sten otherwise the velocity is about the same as a 9mm but with a lower bullet weight

What other calibers do you think would be cool in this gun? What has been done with caliber conversions in tube guns in the past?

I would think bolt weight would be an easy fix compared to getting those Sten magazines to feed another caliber.

im thinking more and more that a 30 luger conversion and ammo that runs up to max 9mm pressures would work well and may not require a heavier bolt.