A few things to remember about the JAG kit:
You must machine the feed rails on the receiver! You cannot go back to the factory internal magazine after you install the kit.
We recommend Ruger factory magazines for the best functioning of the kit. The 2nd choice would be Pro Mag brand magazines.
No magazines are included in the kit.
The lips of the magazine must be spread open to about .540 to allow the rounds to ride up high enough for the bolt to pick them up.
Some minor fitting of the nose piece MAY be required, the nose piece was redesigned so that no fitting would be needed, but all triggerguards are a little bit different.