Say for example you have a carbine with a gas port that is too large. Would adding a heavier buffer be the equivalent to installing an adjustable gas block or something that will regulate the gas flow to a more appropriate amount? I know that a heavier buffer will slow down the BCG thus making it shoot smoother but is this more of a band aid than a remedy?
I have 16" midlength barrel with a .750 gas block seat with a port size of .078 that was measured with a 5/64 drill bit. Even with an H2 buffer, blue sprinco, and Rainier XTC it seems as if it is still a bit over gassed. The recoil is a little harsh and it smells a bit gassy when firing with my nose close to the charging handle. I have been thinking about installing one of Black river tactical’s threaded inserts in the shaved down FSB to smooth it out a bit more.
If I were to go that route what would be a good combination of buffer and port size? I was thinking about using the .076 insert or maybe even the .073. Would it be best to go with the setup that provides the heaviest buffer? For example would the .076 insert + H/H2 buffer > .073 insert + Car/H buffer?
Man… .078" isn’t that bad for a 16" middy. Optimally you’d want to be at an H2 carbine or H2 A5 buffer. You’re close enough in port size that I’d tune with a heavier buffer.
The XTC doesn’t have any sort of expansion chamber. There shouldn’t be an impact on back pressure. But there’s psychological damage form the flash and concussion.
Correct. The larger the expansion chamber, the more dwell time is added, all things being equal. Baffled brakes and comps vent to atmospheric pressure almost instantly.
ESK has said that this is why he included a small chamber on the longer BCM comp (for 14.5" pinning)…to bring it up to the functional equivalent of a 16" middy or thereabouts. He also said that some comps with larger expansion chambers (possibly like the BC design) could add up to 3 or 4 inches of equivalent dwell time to a gas system. That’s a LOT of extra dwell time and can substantially alter the balance of the system.
So, a comp with a bigger expansion chamber (like the BC) means an adjustable gas block become even more important.
I noticed the difference on my 18" barrel with rifle gas when I went from a Precision Armament AFAB-Mini (similar in concept to the BC) to a Lantac DGN556B Dragon baffled brake. The Lantac created noticeably less backpressure in the gas system than the AFAB-Mini. So much so that you could feel it in your shoulder in how the BCG was cycling when shooting off-hand. It does make a difference.
You know what? Pappabear has a BC on one of his Bergara 16" carbines. And the thing I like about them when we first rolled them out with A2 flash hiders was that they were gassed right. But the BC fitted gun runs “harder” and doesn’t have that nice rifle like ejection any more.
That has to be it. I’m going to pop that BC off and shoot it this weekend with a no nonsense flash hider.
Mark, I have commented on the BC’s having a very sharp, yet straight-back shove as compared with other devices. I even got shitted-on when it first came out when I stated that it felt like it increased recoil on some guns. Going by what ESK stated, on some guns, the difference in BCG speeds during recoil COULD cause it to bottom sharper on the rear of the RE (which is one of the issues an adjustable GB addresses).
I’d imagine that, the heavier the gun, the less difference one would be able to feel.
