A few years ago, my son had a similar problem with a Glock 10MM and I convinced him to trade it on a new Glock .40.  Later, I regretted that decision when the gunsmith at the shop we traded with said it only needed a couple of new parts and was functioning fine.  He didn't say which parts, so I can be of no help there.

Is there a legit reason that Glock won't use Underwood?  I have no experience with them.

I have to say it wasn't easy and a long time coming, about two years.  I took some part time work, not just for the 10, but other shooting needs as well.  Along the way I collected everything I needed to reload for 10mm, dies, brass, etc...  On trips to the occasional gun show, I would buy loaded rounds manufactured from new components, ending up with about 400 rounds.  Not earth shattering, I know, but a start.

Went to the range Monday night and the gun was everything we hoped it would be.  Functioned flawlessly over approximately 100 rounds, almost all reloads over a chronograph.  I'll post the data on the range report thread when I get the chance.  I did learn a valuable lesson about how modern loads are downloaded. I picked up a box of 50 PPU 180 JHP at a local gun shop.  Fired 5 over the chrono for grins.  Exceptionally disappointing, to say the least.  Averaged 1050 fps with a low of 992 and dropped the cases less than 3 feet away.  Won't do that again!

FWIW in case anyone is getting ideas, I'm not looking to adopt!!!  

Just last week gave my son his Father's Day, birthday and Christmas gift.  A SIG 220 DA/SA reverse two-tone in 10MM.  The quality of this gun is above reproach and we can't wait to take it to the range.  Ordered it at the Pro-Shop early January and it arrived about a month ago.

I've worked up 45 test loads to shoot over a chrono and for accuracy, so hopefully it will shoot as good as it looks.

I was at the shop last Monday trying to buy spare mags for it, and they didn't even have them, so will just keep checking.

This is my first post and I have to say I have learned a lot in the time I have been reviewing the info here. Thanks for all the info gentlemen.