Okay. Sounds like you'll have to replace the magazine spring. I take it the back of the
follower is raising up on ya'. Contact Ruger customer service, and I'd request a new
magazine follower & spring. Good luck.

ps: I checked, and it appears you can also get the parts from Numrich Gun Parts.
Looks like less than $20.
Here is a link:
http://www.e-gunparts.com/products.a...l=1910zM77&MC=