Posted On September 10, 2021
Posted with little fanfare or comment, VGA resolution thermal video of a recent test of the newly installed (and subsequently uninstalled) VLTOR A5 buffer system and a L.A.R.B. Mod 3 buffer system.
In retrospect, I’m not sure why I thought it was a good idea to try using a 5oz buffer in a 14.5″ barreled rifle with mid-length, direct impingement, gas system using a .075″ gas port. Eventually I’ll swap in a Sionics NP3 BCG and see how an carbine H buffer performs in comparison to the H2 I have currently installed.
Besides the obvious potential for heavier buffer weight over that of the traditional carbine buffer system, the A5 buffer system’s main advantage lies in the increased length of the buffer tube, and subsequently the increase in compression length of the buffer spring that affords. The aim of the A5 enhancement to the M16A4 (the M16A5 as it could have been known, were the system formally adopted) was to offer a solution for reliability issues encountered with the existing Colt C7 and experimental H6 buffer in use with collapsing stock conversions available at the time.
Three needs were identified prior to the introduction of the A5:
(1) Enhanced length of pull over that of the carbine buffer tube and Colt M4 carbine stock adapted for the M16A4 to accommodate some shooters with especially long reach while in prone and other misc. shooting positions (longer than an A2 fixed stock)
(2) give more flexibility and range in terms of buffer weight adjustment or selection to mitigate the effects of gradual port erosion throughout the service life of the rifle so as to minimize dangerous bolt bounce possible with the higher compression spring rate of the carbine length buffer system
(3) extend the available space internal to the buffer tube for the buffer spring so as to prolong the service life of the rifle comparable to that of the original fixed stock and rifle buffer system
The A5 system, when adapted to a traditional carbine where the barrel mass is insufficient to require the full staggered effect of a rifle buffer with 5 steel weight, solely offers two of the three benefits: the increased life cycle of the spring, and the greater length of pull required by few shooters. The average person will find no need for the latter, so the life span of the spring is all that remains as a practical benefit.
There is, of course, the consideration of what having the ability to fit more mass behind the carrier does to the cyclic rate of the stoner in-line piston system, especially on rifles with very long dwell times (such as the M4 and M4A1 carbines with their nearly 7” of dwell distance). However, too much weight obviously leads to the short stroking of the carrier in scenarios where port pressure is insufficient— I.e., mid length gas on a 14.5” in colder conditions and with less powerful commercial ammunition.
Thankfully, the A5 system can be adjusted both ways; one can decrease OR increase the weight as necessary to find the optimal amount of mass to delay the opening of the chamber at a minimal amount of recoil. 5 ounces may have been too much, especially if the A5 system was also oversprung (very common for people to do both), and moving from an A5H2 to an A5H1 or even an A5H0 would have eliminated the issue encountered, entirely.