Do not Dremel your mounts. On the bottom of the locking latch, there is a nut. It's a pain, but you loosen or tighten the nut one-quarter turn at a time. You'll know which way you need to turn it. It may take a few minutes, but ALL of the side mounts are adjustable this way.
Slide your mount onto the siderail and (try to) close the lever. If it will not close, the tension is obviously too tight. Loosen the nut a little at a time, and keep trying the mount.
Once you have made the adjustment, make sure it only takes moderate pressure to unlatch the mount. If it's too tight, it can damage the locking mechanism and make it hard as Hades to remove.
If your mount is made by Kalinka, then this should help.......
Adjusting the Clamp of POSP/PSO Scopes