Slim....
I bought some off of e-bay, very nice looking ones, it took several phone calls with friends (remember Ted,
) before we figured out that the backside was too think and was interfering with the safety and magazine. So the gun might or might not fire and the magazine would fall out! A bit of playing with it, fixed that.
It comes down to that most grips were hand fitted, frames were slightly different by different manufacturers and so my opinion is that the repro guys make them sloppy to hopefully fit most guns.
Ed