Are they worth the extra 10 rounds? I used to own some but can't remember if they a crap or not.... I was gonna get a few for my SHTF gear!

- Clint

I used to keep my 40 rd mags for the range only.... but after a few thousand rounds without a single failure..... they have moved to my SHIF bag!!!

Why?  

From a practical standpoint, the more bullets you have in a magazine, or the longer the length of travel for the mag follower, the greater the chance of a malfunction.  For a novelty, no problem.  For a defensive implement, you really need to weigh the advantages of the extra capacity against the disadvantages.

Advantage:  more bullets possibly available before needing to reload.

Disadvantage:  longer, more prone to snagging.  longer, precludes shooting from prone position.  weapon balance possibly ungainly.  greater length of travel increases chances of a failure to feed.  you only gain ten extra rounds.

In my estimation, ten more rounds isn't worth the effort.  Siimilarly, a Beta C magazine, while offering significantly more ammo than a standard mag, the reliability, or lack thereof, precludes using one in a defensive posture.  

Again, as a range toy, go for it.  I'm all for supporting consumerism when it comes to gun stuff and don't want you to take this as an attack on your idea.  In a defensive role, however, I believe that the science indicates that two 30 round mags beats a single 40 round mag for convenience, reliability and capacity.

Vaughn T, I understand where you are coming from, the answer to your question of why 40 rounders is.... I have several 30's and 20's but was gonna do a mass purchase of mags with a tacticool vest at a local gun shop. He has 1- 30 rounder and 7- 40 rounder's that are new.... with a plethra of old steel 30 rounder's.... I was gonna fill the vest with the 40's and call it good, but can't remember if they are worth the trouble....

Basically my AR is used for varmint hunting and I use the 20's for that when I have my 24" Bull Barrel on it. When I go to the range for some plinking I slap on the M4 upper and do a few mag dumps.... Thats what I'll be using these 40's for.... Or if the Zombies ever come around

- Clint

Hmmm... 40 rounders that are either VERY EXPENSIVE or unreliable or 30 rounders that are both reliable and inexpensive.

Just couldn't bring myself to purchase the 40's, I went to a different Gun Shop today and picked up 6 more of the Colt (Alum w/green follower's) 30's like I already have. Picked up the tacticool vest too..... The wife made me go put it on and started gettin' all frisky, so I won't be puttin' that thing on in the house again.... LOL   Good thing I had my AR handy or she woulda had her way with me

- Clint,      thanks for talkin' me out of the 40's ya'll.............

US GI is the best.