Just picked up a minty single stack Romak 991 . Looks like it has the standard bolt but the narrow front trunnion . I’ve opened up a few single stack wasr 10s but never messed with widening the trunnion . Has anyone done it before ? Thanks in advance

You will need a mill or a dremmel.  My dad did it to one and got it to take take standard mags but had to cut off a good part of the inside part of the rivets and decided to modify a few mags rather than mill off more trunnion/rivit.

When he passed and I ended up with it, I took it to a shop and they milled it a little more and redid the rivets. Now it takes standard mags fine.

Mine has a single stack bolt, but still strips both sides of mag.