As to my question, you said the magazine was to big. What do you mean to big? Is the magazine loose in the well and how so? Is is sliding around front to back or side to side? If its front to back, then yes you can use a spacer, just like the Glock does. If its side to side, you can use spacers, but you'll probably want to disguise them some how. Or are you worried about the rounds not sitting right in the magazine? If thats the case, then you might be better off to recut the magazine. If you try to use spacers, and plan to have a springloaded magazine to feed the rounds up, then you could run into problems with jamming the spring from faults in the spacer, welds or anything else.