Might be a known issue but I found the hard way that the MecGar base pads are wider than CZ brand.
I have grips with extended 'magwell' sides and rear, covers the full length of 18 rd OEM mags.
The MecGar 10 and 19 rd both have slightly wider plastic base, mags would insert but not fall free.
EZ fix with surform [woodshop cheese grater] and 60 grit paper but FYI
