Finally got a chance to take my carbine out to the range today. Shot about 150 rounds through it, had a couple of failures to feed early on but it settled down quite nicely. Spent most of the time tuning my optic, a Bushnell Trophy red dot sight, and finally got to the point where I could regularly hit the 200m gong. Where everybody else's rifle makes the gong go "bong", the puny little 9mm bullet only has enough energy left for a "tink". About a 40" holdover from a 50m zero, with the muzzle velocity around 1300 fps ( measured on my chronograph ) using AE 115 gr ammo.
Lots of fun to shoot. and the other folks that tried it were all smiling and saying " Now that was fun !! ". Sounds like a success to me. Interestingly, there was a little bit more recoil than I expected. Not much , of course, but maybe the recoil reducing pad on the stock isn't such a silly idea after all.
Also, I found a pistol mag that works. Had to Dremel out some of the inside of the pistol grip ( very easy; love that plastic ) to seat the new mag a little further in, and a bit of tweaking on the feed lips to make it match the Hi-point mag. So now I have a working 10 round pistol mag.
The bad news; it's a fairly rare mag. I was lucky enough to find them at the local gun store. I'll make another post when I get a chance to call them and ask what the exact model of pistol is, but just from looking at some other mags and after getting a chance to really get inside the guts of the pistol grip, I still think that it might be a good idea to take a serious look at a Glock mag. You would have to Dremel away the inside of the grip all the way, but being plastic, that goes very easily. and the Glock mag looks like the feed lips are very close to the right dimensions ( it looks like they could be "adjusted" if necessary ). Also, if you used a mag for a Glock 22, it would likely hold 12 or 13 rounds of 9mm, heh.
More later.