Carbine Support Grip
I get quite a bit of emails as to why I grip a carbine the way I do with my support hand. The opening segment of Tactical Arms shows me shooting an M4, as do a couple pics that have been on here and the web.
First off, I didn't invent this grip even though it's been attributed to me on more than one occasion. Unfourtunately, I don't know where it came from, so I can't give credit where it's due. I would guess that it began as a three gun thing, and maybe John Shaw brought it to the SEAL Teams?
In any case, there are quite a few pro shooters out there besides me that run a carbine with this grip (Jason Falla, Tony Reeves, Looey Gines, Billy Solares, Brian Searcy, Larry Vickers, Chris Costa) or a slight variation. And to be honest, I didn't originally do it for the same reasons I do it now.
The reason for placing the hand as far forward as possible is to have better control and balance on the gun. Especially when shooting from standing or on the move. If you think about a correct pistol grip, all I'm doing is replicating that on a longer plane. Gripping an M4 closer to the mag well would be the equivalent of doing a cup and saucer grip on a pistol. Now, an important thing to note is that when you go to a supported kneeling position, you can't use this grip. You must roll your hand slightly more under the rail so you can make contact between your elbow and knee. It will work in the prone though, no problem, especially if you rest the mag on the ground.
I place my thumb over the top rail because that's how I activate my laser. The on/off button for all IR devices is on top. I 100% hate pressure pads and cables of any kind (if you're doing anything more than standing still, they will screw you eventually). I discovered by accident that when shooting a carbine without a laser, that thumb does an almost unbeleivable job of reducing upward recoil during rapid fire. To the point that you can keep up with iron sights and this grip against a guy that has a red dot and does a traditional under grip.
So does your hand get hot? Not really. If you decided to unload an entire mag at once, yes, it would get uncomfortable. If that's you-wear gloves.
A few years ago when Larue and others came out with rail systems that where longer than normal 7" issued one, a lot more people started to adopt this style of support hand, either on purpose or by accident. My new M4 will have an extended foregrip, no doubt, for the sole purpose of getting my hand as far forward as possible for better overall control of the weapon.