Interesting thread!
Haven't yet had the time to read through all the posts, but when I did so one question crossed my mind: How about reducing the playmo-guns caliber? This can easily be done (I know german board member funky has done so for almost every playmo gun that's available), while the gun is still able to shoot. OK, one cannot use the original ammo any more, but instead use small lead balls (originally intended as curtain-weights) of the right caliber.
I haven't tried this myself yet, but I assume that the long range fire would become more efficent while the overall range of the gun would be a bit shorter (major advantage is, that you would never run out of ammo

).
Besides, I suppose even canister fire would be possible at short range ...
EsDoc