HFC HG133 shell issue. Other brands?

[Mineshaft]

I'm trying to source some more shells for a HFC HG133 gas revolver, but they're unavailable in the UK and none will ship form the US.

So my question is this, will other brands of gas revolver shell work in my HFC. For e.g., could I use a 6mm Dan Wesson shell?

It's probably a really stupid question, but i thought i'd see if any of you guys had a solution.