This is the base in question:

http://www.midwayusa.com/product/315...t-action-matte

On the bottom of the mount there is a ridge that runs perpendicular to the long axis of the mount, just behind the 2nd screw boss.

Is this to catch the lip of a right port action?

I'm looking to use this mount on a RBLP PTA, should I just remove the ridge?

Thanks, Matt.