We have owned a few MKII 6" barreled Rugers, presently one in ss. They are unbelievably accurate for fixed sites, I have shot many grouse threw the neck while out deer hunting in Colorado and have shot many digger squirels up to 100 yards. They are one of many another Ruger products that have never let me down.
I'll bet a spring isn't seated properly. Those rugers can be a pain to dis/reassemble. I know there's a couple guys here that could help you out better. I wouldn't just settle for having to pull each mag out from now on. Good luck.
I have (my wife actually has) a Ruger MARK II 10" Stainless Steel Bull Barrel, and 5 magazines. All the mags drop free. Pull your grips off then try your mags again, and locate the friction. Sometimes the grip panel screws are a little too long .