Sometimes,, the spacers, if their diameter is larger,, can rub against the mainspring. I always try & buy the smallest diameter spacers I can. But,,if the edge of the spacer is rubbing against the mainspring,, you can remove one grip panel,, (the socket side,) slip the spacer over the already inserted screw shaft, tilt the gun, grip frame etc to where the spacer is positioned towards the grip frame & away from the mainspring. Holding it in that position, assemble the grips. When tightened,, it shouldn't shift & touch the mainspring.
I have cut a few spacers down too much. I had a few go .010 (.4990) and I chose to not use them on any guns that measured closer to .5000. I have had a few frames that were polished below the .5000 enough to where I have used the shorter spacers.