I pick up a tactical 30 a few weeks ago,
when I load the factory magazine that came with it, the last round on top dosn't seem to be in line with the feed lips,
Its "nose diving" and willn't chamber.
I have to push down on the round in the magazine so that it will seat right, is this normal?
It is possible that the spring was mis-installed. Dismantle the mag, and rotate the spring 180 deg on its' vertical (long) axis, and try that.
Sometimes the spring has to be installed "just so" to prevent the follower from nosediving. You might also have to flip the spring end-for-end and try that. Since most followers have some sort of hole or slot by which the spring is secured to the follower, there are only so many ways the thing can be put together. Common sense and a little experimentation will probably set things right.
If that does not work, and it is a Ruger factory mag, contact Ruger. They will make things right.
Several of the factory 20-round mags I purchased for my mini-thirty tactical did this. After a half-dozen firings through the rifle, it stopped.
Thanks for the info