Not talking one of those old Colt “half-moon” carriers but a run-of-the-mill semi-auto one. Is the weight difference between a semi and a full-auto carrier enough to warrant a bump up in buffer weight, or is it insignificant?
Looking on the interweb, there is about .8 ounce difference between the lightest semi carrier and a full auto carrier. Each “step” in carbine buffers (H1, H2, H3) is roughly .9 ounce. It might be worth going to the next heavier buffer to offset the semi carrier, but you really have to shoot the gun first, then go from there. There are so many factors that come into play.
Andy
Negligible. If the gassing is rich, a heavier buffer might be optimal.
You also have the option to change buffer springs. Or jump into adjustable gas. I run a 1.5oz buffer with lightened carrier… gun runs like a typewriter
I’m not a fan of aftermarket springs at all. I insist on my guns running correctly with colt factory buffer springs.
Honestly i dont think you will even notice a difference. Changing carriers and buffers, I couldnt run the gun with much less gas. What buffer are you using?
I have an LMT Enhanced BCG coming (they were on sale a few days ago). It is the semi version. I have FA carriers in all my weapons for now, but I have a stripped Knight’s lower and now an LMT EBCG so it’ll probably be my next project. Was just wondering if the weight difference was insignificant and markm knows his shit so I’ll be confident that it won’t matter. To answer your question though there is no buffer yet assigned to this future build. It could be an H or an H2 (probably an H if I use a midlength gas system).
Not enough of an issue to be concerned with. If you need to tailor your spring or buffer, it will be due to gas port sizing or similar issues.
Having a selection of buffers is always good. Your going to be fine. Hope the build comes out to your liking!
I cannot find the info handy but I believe the LMT enhanced carriers are very close in weight wrt FA vs SA. I have both and want to say the weight is within a few tenths, not almost an ounce. If I get some time tonight I can pull them out and weigh.
I was looking at this too. There was a post in a thread on Semi vs Auto carriers where one of the moderators said there was only “.2 ounce difference”. Now, that number looked low to me, so I’ll wait until the LMT Enhanced BCGs show up, then I will measure.
BUT, there is one more thing to consider. The Enhanced carrier has an extra gas hole in the carrier and a different (longer I think) cam track. I was told that the Enhanced LMT BCGs require less(?) gas to cycle. I think its because the cam leaves the bolt locked longer and therefore gas is directed through the gas tube for a longer period before the bolt is unlocked.
Even if my memory is faulty about exactly how the Enhanced BCG operates I do know this…The changing of the weight of the carrier will not be a simple one-to-one change as the differences in the gas system will change the dynamics as well.
I keep every weight of buffer. C, H, ST T2, H2, H3. I’ll start with an H. Or I might go A5, but I don’t have but one A5H3 buffer, so I’d have to buy an H2 at least.
In any case, it may be a little trickier because of the Enhanced carrier. How much buffer you need will also be determined by the port size. Someone said use an adjustable GB. I’m not convinced of the reliability of these yet. I just got my first one (SLR Sentry 7) and have not installed it for testing yet. After I put 500 rounds through it without cleaning I’ll be able to determine if I want to use them.
Sorry for the long winded answer.
When I get around to purchasing another upper it will probably be a BCM 16" BFH ELW barreled one, which of course is a midlength. I will start with a H buffer and go from there when the time comes.
I run a 9mm buffer in the one AR I have that has a semi auto carrier. I have a H3 buffers in my other AR’s and I tried one of those out first with the semi carrier and it functioned fine. I picked up a 9mm buffer just because it was cheaper and the rifle is a range toy. David
The extra hole vents the gas from the expansion chamber quicker.
The cam track has nothing to do with how long the gas flows through the gas tube and into the expansion chamber. The longer cam track of the Enhanced carrier simply delays when the bolt begins unlocking, giving the bore a fraction of a second more blow down time before the case is extracted. Gas stops flowing into the expansion chamber when the gas key separates from the gas tube.
I’ve only tested one Enhanced Carrier but compared to a standard parkerized carrier, the Enhanced carrier required one click less on the adjustable gas block to achieve bolt lock back on the last shot
There are some distinct differences between the conventional M16 carrier and the LMT FA enhanced carrier in a few ways besides the basics on a print, but with more of a focus in function characteristics. More importantly though is identifying those characteristics and using them in a way to take advantage of positive attributes for function without going towards a path that bring up net negatives for a use.
While I don’t use the semi version of the LMT enhanced carrier, I wouldn’t assume that mass difference is automatically inferior compared to a full auto one. I’ve been in this long enough to know that the advertised buffer weight does not always follow through with actual weight. As long as a user is not at either ends of the spectrum of total reciprocating mass needs, it’s not that hard to come up very close to very similar total reciprocating mass with minimal exploration. Tungsten densities differ, total masses can differ from that, many are not hard to find.
We can go into a more in depth discussion about this if needed.
If indeed the difference in carrier weight is .2 ounce as has been published in this forum (believable I think), or even .5 ounce, the difference will be negligible. In fact, I cannot think of a real reason to be concerned about the use of a semi-auto carrier instead of an auto-carrier as long and the semi-carrier has a shrouded firing pin.
I agree that the design of the LMT Enhanced is different, but it makes no sense that the Enhanced BCG would have such a small window of operation that .2 ounce would make a difference in a semi-auto rifle. And why would LMT sell them and sell rifles with them installed if they won’t operate properly?
With all due respect I think the concern about the operation of a rifle between a semi-auto and auto BCG in a semi auto rifle is completely overblown on the internet and is a red herring. I have always bought Auto BCGs because they are common and everyone says, “buy an auto carrier”, but the truth is that there is very little difference unless you are getting a semi-auto BCG with an un-shrouded firing pin. I would avoid those.
I think that some of the point was missed. It’s not that a fraction of an ounce makes that much of a difference, it is that it’s pretty easy to get to a total reciprocating mass for whatever that requirement may be to equal the FA counterpart for most.
The LMT enhanced carrier does some things differently, compared to the base M16 carrier. We can look into those if interested.
True. I bought two full BCG, and one stripped carrier in this same sale. I never see these things on sale so for 200$ a pop, or 40% off and free shipping I jumped on it.
At first I was like ‘but they are semi, thats bad’ then I thought about it and realized they won’t go in an auto gun, what do I really need an Auto carrier for? I also hypothesized LMT for function would keep weight similar. This thread validated that for me.
its not the weight difference, its the mass x the velocity.
Just think of the difference an extra 20 grains of bullet weight can make at the same velocity.
Assuming .5 oz, that’s over 200 grains increase. Admittedly at a much lower velocity than a bullet. But my buddy newton tells us about equal and opposite forces, etc.
Since its gas operated its not a linear change in velocity like blowback would be. But it still changes timing and carrier velocity if buffer weight remains the same.
It could be better to look at the different timing events within the confines we have. If we breakdown the different events, we can have options that can better place ourselves and avoid some negatives.