Originally Posted by bikeryoda
I bought it brand new about 8 months ago. It is a stainless ranch rifle.
Ruger has had thousands if not millions of complaints about their mini's ejecting brass into the next county. To reduce the distance brass would fly many Mini owners would install reduced sized gas bushings. These have a smaller hole in the gas port bushing allowing less gas to get into the ejection system thus reducing the distance brass would fly. Ruger finally listened to it's customers and reduced the size of the gas port bushing on the New 580 Series Mini, which is what I believe you have.
Now that the gas port bushing is smaller than the old brass chuckin Mini's you have two choices to make it function. Get a larger gas bushing http://www.ruger-mini-14-firearms.co...ccessories.php
or switch to a slower burning powder.
I like ball powders for my 223 for ease of metering and they fit though the little 22 cal hole better. If you can find them, I would give either 335, TAC, 748, 2230, BLC-2 a try. They are all ball powders and slow enough to give you the port pressure you need. My favorite is TAC.
BTW, make sure your mini is clean and lubed.