No one recommended the Cobra mag; is there a reason?
I mentioned it and recommended it in post #16. They work great in my opinion, and are well made and thoughtfully designed. Tripp also has a lot of detailed information on his web page about magazine function and design that is educational. He explains exactly how and why his magazines are built the way they are, and he invites you to call and chat about it. His mags provide much better controlled feed than Wilsons. Plus you can call him on the phone and ask about that in person. I've had a tough time getting Bill Wilson on the line to explain his design, so that adds value to me, too.
Their "conversion kits" are also great, as I recommended. Great follower - which is I think their great strength. The follower is:
1) dimpled, for last round retention
2) grooved, for the same purpose
3) skirted, to:
a) protect aluminum ramps
b) prevent the follower "bobbling" fore or aft on the last round and allowing cartridge drop as the round is moving forward, creating low ramp strikes. After my own testing, I have found this the cause of many last-round ftf issues, but never see it addressed very widely. Much stiffer springs can usually fix it, but a skirted follower completely eliminates it as an option, weak spring or no.
4) steel insert in the polymer for positive slide-stop activation
These are the most evolved and intelligently designed followers I've ever seen, and no one makes anything with all of these features. Plus, for $8, you get a nice mag spring, so this is a great deal if you have quality bodies and just need to upgrade to the follower/spring.
I think Cobra mags are the best things on the market - I like factory Colt, and that is usually my first choice, but Tripp is slowly winning me over to them. The reason Tripp mags aren't regarded more highly is:
1) They don't have the marketing muscle and size of Wilson
2) They only sell direct to gut end-user costs, so you don't see them in catalogs online all the time.
So do not overlook Tripp, they are well worth it, especially if you are having last-round-hold open problems, have an alloy frame, or also having a drop-free failure with other quality mags. Their followers can really help with these issues where not all others can.