I have received 2 emails recently asking why I mount my front sights further back than they need to be on my carbine’s free float rails. The reason is that I use them as a thumb stop. There is at least one company out there marketing a thumb stop for use on AR-15 railed hand guards. The principle is simple. A thumb stop simply gives your thumb a repeatable index point and something to pull against when using a thumb over/thumb wrap grip with your support hand.
Thumb stops are good gear and they can make it easier to aggressively grip the carbine and pull it back into your shoulder to control recoil. However, you might not need to spend the extra money to buy one or put up with the additional weight (however miniscule it is). If your carbine has an extended free float rail (a rail that extends over a low profile gas block), consider moving your front sight back slightly to serve as a thumb break. You may have to experiment slightly with the location, but with some trial and error, you can find a location that falls naturally under thumb. You will be giving up some sight radius but these are your back up sights and you will likely still have a longer sight radius that you would with a standard front sight/gas block.
I have used this method with several brands of rail mounted front sights and all worked perfectly. Troy Folding Battle Sights have a nice bevel on the leading edge that makes them just about perfect for this technique. Magpul’s MBUS sights work well too and can be lightly stippled for increased grip. If you are using a rail mounted fixed front sight like the Troy Fixed Front Battle Sight or LMT Fixed Front Sight, consider mounting it backwards. The diagonal surface of the of the rear of the sight is more comfortable to pull against and the sight will still work fine. Just be ready to endure all the gun shop know-it-alls telling you that your sight is backwards.
I should also mention that this technique works especially well with a hand stop. I use IWC Weapon Control MOUNT-N-SLOTS (use code “triggerjerk” for 5% off from IWC) on 4 of my carbines in conjunction with the front sight/thumb break. The hands stop gives your fingers something to pull against on the bottom of the rail and the front sight/thumb stop gives your thumb something to pull against on the top of the rail. This set up also gives you 2 very easily found index points that allow you to recreate the same grip every time you touch the carbine.
This certainly isn’t a complex idea. I am not even really sure that it is original. It is just something that has helped me lock down my grip with the equipment that I already have. Try it!