Not stoopid at all.
basically, the difference between a regular and a mini cocker is about an inch, maybe an inch+a half.
On a regular cocker, the front reg screws into a FRM/FBM - front reg mount/front bottle mount, also called a vertical ASA (that one I don't know).
This ASA is on the bottom of the body, between the grip frame and the front block (that lump that your 3-way, ram etc screw into).
On a mini-cocker, the front reg (if there is one) goes directly into the bottom of the front block, which is right next to the grip frame (the front components are closer to the grip).
You do lose out on valve chamber size though, which means (if I remember correctly) that the operating pressure needs to be slightly higher.
However, a mini and a stock cocker with the same barrel will still be the same length from back of bolt to tip of barrel.