not sure which ones those are? the first stick mag i got had a completely different connector to the hopup and wasnt useable. (some chinese cheap thing) those stick mags are the king arms Thompson ones and very little problems with them. in fact id recommend them over the drum mag any day, nearly hold as much ammo(420 compared to 500) easier to carry etc. there's a little movement but then id guess there would be in such an old design of weapon. not good for lefty's do to placement of mag release(catches and releases mag very easily. if you wanted i could possibly do a vid showing how well the mags compare in it?
also ill throw in this pic to show ya the main problem with the drum mag, soo much wasted space for the size. was easily able to modify it myself to tak ea few hundred extra rounds and balance it a bit better...