In for info on the above ^^^^
OK, I'll try to keep this short. The Vltor A5 buffer system utilizes what is essentially an ar10 length receiver extension, a rifle length action spring and a specially designed set of buffers that are longer than typical carbine buffers by approximately 0.75“. Bravo Company makes an identical kit also. Eric Kincel, who now works for BCM, originally designed it and holds the patent.
Warning: it is not compatible with standard buffers and use of regular buffers will result in damage to the lower.
Cons:
Cost is about $100 per lower.
The RE is 3/4" longer, so most stocks will not collapse all the way down to the rear of the receiver. A few stocks like the EMOD and ACS will cover the tube though, because they are longer by design.
Pros:
The rifle spring is softer than a carbine action spring. This is the key. The buffers are longer in order to accommodate the longer tube. The buffers are also heavier than what you're used to. FYI, the most common buffer used is the A5H2. I equate it to a standard H buffer in terms of compatibility.
The combination of a softer spring and heavier reciprocating mass results in a system that behaves like a rifle buffer system, but shorter in OAL. It has several benefits, the best of which is that it is very forgiving. Meaning it works equally well, with and without a suppressor. It also provides a noticeable change in the recoil impulse, making it much softer and very smooth. Set up properly, the result is a flat shooting, very controllable gun.
It's a good reliability upgrade due to the innate forgiveness of the system and allows faster, more controllable follow up shots.
I've been running them for a couple of years. For most of that time, I've been using the Springco Green rifle spring. The green spring is made of chrome silicon steel. It isn't stiffer than the milspec spring, but CS does have a faster rebound rate. The more I've shot it, the more I've realized that the rebound stroke of the carrier is causing a slight downward dip of the muzzle between shots. The milspec spring (Colt) produces a more fluid stroke and slightly smoother (not softer) recoil impulse. Note: CS basically lasts forever and doesn't take a "set". The milspec spring will shorten over time and has to be replaced once it falls below the minimum acceptable length. This is normal for milspec rifle and carbine springs.
Depending on the gun, gas system length and gas port size, an A5H2 or A5H3 are the most common buffers used. Carbine gassed 14.5 - 16" barrels may call for A5H4. For guns with a smallish port, like the BCM 14.5 midlength barrel, an A5H1 may be appropriate.
Final note. There are two versions of the A5 receiver extension, the standard A5 and the A5SR. If you're using a standard length stock, like the milspec stock, SOPMOD, CTR, MOE, etc, you want the A5SR. The hole positions are different and the SR version allows the stock to fully collapse on the rear of the tube. This is important when clearing malfunctions, specifically when performing a mortar.
That's it in a nutshell. If you guys have any questions, let me know.
