First off, let me start by saying I'm not a Glock fan at all, but they are the easiest to get into 10mm.  I already have a G21 that I converted to 10mm, so this would be another Glock I may consider buying.

There is a LGS that has a pre owned G30 with NS for $425.  I am considering buying it and swapping out barrels to make it a 10mm.  I really wanted to find a Gen 2 G29SF, but I'm not finding any locally.

Can anyone tell me what differences in the G30C...I heard that the slide is slimmer.  What frame do the G30s use?

I'm assuming it's just a barrel/mag/recoil spring swap and possibly extractor?

Any issues with conversion...LGS guy kept on insisting you cannot do the G30 to 10mm conversion, which is know has been done by some folks.

Also, any issues with say using the 4.6" G20 barrel from say Storm Lake in the smaller G30?  I've seen some pics of folks using a longer barrel, but I wanted to make sure.

Some very knowledgeable folks on this forum that I have a lot of respect.

I dropped my 10mm Lonewolf barrel into my G30sf and fired it without any problems, albeit it was only 30-40 rounds. I wouldn't carry it, but for the range it worked okay. The G30s uses the same frame as the G30, but the slide from a G36. I don't think those can shoot 10mm because of the lighter slide -- I may be wrong. Someone else will chime in who knows.

I also think the G20 barrels have a different spaced lug than the G29. You have to get an extended barrel for the G29/G30. You can't drop a G20/G21 barrel into the smaller version.

Good luck on the search for a G29. I bought a G30sf because I was looking for a G29 a few years ago. Last year I found a used G29sf. Used ones are like unicorns. 

A LGS had a used G29SF...I passed on it and am kicking myself because it was a great price and didn't look like it was fired much.

Guy on the other side of PA has a used G29SF for sale...I figured once I factor in shipping and transfer fees...I might as well get one at Cabelas as they also have a used G29SF.

I was looking at getting an aftermarket barrel to avoid any smiley issues and to give me better velocities with a 4.6" barrel.

I know, I was in my LGS about 5 or 6 years ago just browsing and he had a G29 Gen 2 in the case. Still had the the copper lubricant on it so it wasn't fired much. I gave him the asking price of $400 and took it home. First time at the range it was obvious it needed a new recoil spring. Replaced that and it hasn't missed a beat since.

I picked up mine for $450. It came with a Lonewolf 10mm barrel, and non-captive steel RSA. The owner was going to shoot heavy lead bullets. He purchased a Glock 40 after I bought the G29.

Good score.

I have someone local who has a G20 and G40 with RMR that we are working on trades for some of my firearms that I'm not using.

For someone that doesn't like Glock, I may end up with three  Glocks in 10mm.

10mm is fun. Good luck on the trades. The G40 is on my want list.