I have two 10 round pro mags, and one 15 round promag....the 10 rounders took about 20 minutes each with my dremel, and some needle nose pliers to get them to work correctly, and the 15 rounder took a good hour or more.
With the feed lips being at an incorrect angle, I don’t see how yours could work without jamming. Pro Mag knows about their design flaw, but they aren’t willing to do anything about it. They stated that people still buy their products, so there is no reason for them to change the design, even though it doesn’t work from the factory (I guess none work right, except for yours). Sending it into them wont do any good, because like I said....its a design flaw, nothing is breaking, they just were not made to fit the hi-point carbine correctly.
If you hold the factory magazine next to a promag, you can see the difference in the feed lips. The hi-point magazine is angled inward at the top, the promags go straight up with no bends or contours. This causes the bullets to nose dive when the slide pushes them forward instead of pushing up into the chamber.
but dont just take my word for it:
http://www.midwayusa.com/eproductreview.exe/GetReviews?productid=136236
I will check into the 30 round drum...Im willing to buy one and modify it like I did my others just to have the extra capacity.