The two brands of magazines that I'd recommend are the
Tripp Research Cobramag and the
Wilson Combat Wilson-Rogers47CB. (Yes, the 47CB, a magazine designed for .45ACP, works perfectly in .40S&W too. With no modification either. It's the best of both worlds.)
Tripp, you can buy directly.
http://www.trippresearch.com/
Wilson, you can get from
Brownells
http://www.wilsoncombat.com/
http://www.brownells.com/.aspx/pid=16398/Product/1911_AUTO_WILSON_ROGERS_MAGAZINE
While I like some Metalform magazines, I
don't recommend the
Metalform for .40; for me they were all
jam-o-matics, but, if you want them, you can get them from any STI dealer or our STI importer,
Freedom Ventures.
http://www.freedomventures.ca/
See these BrianEnos Forum topics:
Best mag for .40 single stack, Which brand is best?
1911 Magazines For .40
Single Stack 40 Mags