I have a Fobus for a Keltec/LCP .380 (with a tension screw) that works perfectly and is very comfortable. However, I also have one for a Keltec P-11 (without a tension screw) that was VERY tight....I used a file to loosen it a bit where it was binding and it works ok but not reassuring enough that I use it for EDC.
Using your Ruger UNLOADED, insert and remove several times and it should mark the inside enough to see where it is dragging. A file/Dremmel can help but I'm not sure if it's worth the trouble. I was going to send the P-11 Fobus back but decided the shipping cost wasn't worth it....I store it in my box of other useless holsters.
Fobus has a good design but I don't think the quality is there for several models....I have a friend who continually presents his pistol AND Fobus to his target when practicing. On a good note, it may surprise the BG enough to make him hesitate his attack....I can almost hear his thoughts "what the heck IS that?"....Lol!