ProMag looks like the only source for new mags. Do they work or are they ProMag?

Ebay has some buy they are crazy pricey

I had a Promag mag years ago for mine and they are garbage like the rest that they sell. The metal lips don't hold up well and the springs don't last. I would buy a used mag and get a new spring for it. Unfortunately, they are not always easy to find either at decent prices. Mag prices for obscure guns are not cheap but most pistol magazines average around $30.00-40.00 anyway, so your not alone. Numrich has them for $42.00.

Out of stock now, but I've had good luck with Manventure Outpost. Get on their notify list.

Never buy ProMag junk!

Promag is shit. I got two of their extended ten rounders. The feed lips don't hold the ammo in place. Other than the range they have no use. I have my stash of factory mags and will be holding on to them like gold.

Another vote against ProMag, I've never had one that was worth a crap.  I used to occasionally pick up 3rd gen S&W pistol mags new from CDNN but I haven't seen them on sale there for a while. 

Agreed.  I picked up a couple from CDNN or Midway about a year ago, but neither has them now.  Keep looking, I'm sure they're out there.

https://www.gunpartscorp.com/Products/1491640.htm

http://www.gunbroker.com/Pistol-Magazines-Pistol-Clips/BI.aspx?Keywords=4506+magazine&Exclude=pro+mag

I found this but also found several spare mags at a local gun show so I never tried to convert any.

Ive suggested converting 1911 mags since I bought my 4566TSW last year. Even the local gun show had mags over $35 used, it's no help to see posts from owners with 15-35 laid out to use with the 2-3 guns they own. There is apparently some concern they are drying up so it's getting to the same situation as .22LR three years ago. Hoarding. And nothing can be done about it. It really is first come first serve and money talks.

The 1911 uses the same stack angle - and the rest of the mag copies the working clearances necessary for the .45, so critical differences are minimal. The feed lips seem to present at the same angle and the S&W has a far superior feed ramp design which can compensate if there were some issue. It's why the slide sits slightly higher - the ramp is one piece and the barrel supports the case well.

About the only difference is where the slide catch is positioned and that shows that the diminishing supply of S&W mags isn't that big a deal. What seems to be missing is someone who will bankroll having 10-25,000 made - or more. It's a niche product to many as the guns are no longer made and the whole gun market is leaving full metal frame guns behind in yesteryear.

Except that the 1911 market is still growing, and it's not that hard to punch the relocated mag catch at the correct location. APEX is in the market to make parts and has expressed interest in making some for the 3Gens, they have the swing to see magazines produced and enjoy the profit that can bring in.

We're just in the 'tweener' time where the original ones are drying up and the new ones aren't out. If you need mags then quality .45 mags are out there - that and Mr Dremel can produce working ones. But - they won't be cheaper, 1911 mags are the same prices new or used. There are just a lot more of them.

One analysis of submachine gun mags used in WWII German gun showed it was the height from the top down and the body angle which were critical for feeding. While a lot of owners would caution using a modified mag I find it somewhat laughable that in the world of guns everybody mods the gun all the time - triggers, springs, sights, grips, extended controls, it goes on an on. All completely useless if you don't have a working mag in it.

I'd rather have a modded Chip McCormick 1911 mag in my 4566 than a Promag. It's either that or shell out $45 - and going up - for used ones which have to be proven to still work. Some might say I'm throwing away the cost of a good 1911 mag but no - adding a new mag catch doesn't affect it in a 1911. If you have both, no big deal, or rather, big deal, you won't suffer if you mix them up.

Of course it sounds whacky but then owning a S&W 3Gen and not a 1911 should define it.

I would buy from Numrich.  They have factory in stock right now.  They weren't a couple of weeks ago.  First link posted by Bradd_D.