Help with M16 malfunction

M

Machineguntony

New member
Tonight, while shooting my M16, the bolt refused to go back into the buffer tube. I disassembled the upper and pulled out the recoil spring in the buffer tube, and a ring shaped piece of plastic fell out (see pic below). I'm thinking that the ring is a piece of the buffer. Am I correct?

One of the guys at the range said that I need an H3 buffer, as the machine gun combined with the short barrel is probably over-gassing the gun. Do you guys agree?

What buffer do you guys recommend?







This is the gun. It is a registered M16 lower, with GI auto sear, 11.5 inch Colt LE upper (not the original upper), with some silencer that I forget the brand of. The buffer is also not the original buffer. It is just the buffer that came with the collapsible stock. I run this gun in silenced full auto a lot. A very fun gun.

 
I'll bet you're right, that's most likely a piece of the buffer.

I'm guessing that you're using a lightweight carbine-weight buffer because that's what comes with most buffer system/stock combo packages. A carbine buffer is way too light for your setup; the full-auto and the short barrel don't help, but the biggest thing over-gassing your gun is the silencer. Your BCG is unlocking too soon and slamming way too hard against the back of the buffer tube, and that's why the end of your buffer is all beat up. You need an H2 or an H3 buffer. Not only will a heavier buffer slow down the cyclic rate, making the gun more controllable and greatly reducing parts wear, but it will also lower the amount of gas you get in your face.

I have a similar problem with my new 10.3" LMT, for some weird reason LMT shipped it with a carbine buffer. It's already overgassed without my silencer, and way over-gassed with it. My buddy loaned me a heavier H buffer, but I didn't even bother to try it yet, I'm sure I need an H2 or H3.

Last night I was online looking to order one or the other, and I came across Griffin Armament's SOB buffer (stands for Suppressor Optimized Buffer). It's designed to handle the extra pressure that a silencer puts on a buffer system: It's supposed to cushion the blow better when the buffer hits the end of the buffer tube. I don't know if that part works or not, but what I like about it is that it weighs a little more than an H2 buffer, but not as much as an H3.

I want the heaviest buffer that will still allow my LMT to run flawlessly without the silencer, and I know that an H2 will do that. An H3 will work even better when suppressed, but I was worried it wouldn't be 100% reliable when the rifle was shot unsuppressed and really dirty. So the weight of the SOB seems perfect. It should arrive within the week and I hope to be able to test it soon after that.
 
I'm no expert but I would get the heaviest buffer you can that will allow the bolt to lock back. For example, you can put the H2 buffer in, load one round in a magazine and if the bolt locks back after firing, try the H3. If the bolt won't back with the H3, then use the H2. With a suppressor, you may have to go to an adjustable gas block.
 
MT,
In my 11.5, I use either an H2 or a 'dead blow' two piece buffer I picked up at a show.
Seems smooth with my loads and the H2, and a pal wants to try the two piece for his Shrike.

With the standard weight carbine buffer, the gun runs fast (to say the least).
Figure that can't be good.

If my camera was not in the shop, I'd take photos.

FWIW
Your photo makes it look like the roll pin for the plastic bumper is backing out.
Mine were doing that and hanging on the spring during assembly (and probably during firing as well),
so I rolled over the ends over with a tapered punch and filed things flush.

I've never seen a buffer in that shape that did not come out of a Shrike!

JT
 
Machineguntony said:
Should I get an H2 or H3? How do I know if I should be using H2 or H3? Is there a test?
Click to expand...
There's no way to know for sure without trying it. An H2 buffer would almost certainly work, but an H3 might work even better. But it's also possible that an H3 buffer would be too heavy and the gun will short-stroke.

Like 2damnold4this said, you just need to test it out. Try an H3 buffer, and as long as rifle cycles properly and the bolt consistently locks back on an empty magazine, you're good. If it doesn't, go with the H2.

Also, keep in mind that you should make sure it runs properly without the silencer if you plan to shoot it that way. My LMT is going to be my primary HD rifle, so I want it to be as reliable as possible in every configuration I could possible shoot it. So I need a buffer that will work even without the silencer and with the rifle really dirty. However, if this was just a range gun that I shot only with a silencer, I could afford to go with an even heavier buffer; it might not work without the silencer, but it would be even smoother with it.

I suggest buying both an H3 and an H2 and testing them out. You'll probably find a use for the other one down the road. Some people will suggest only buying an H3 and if you need an H2-weight buffer you can just switch out some of the internal weights from your current carbine buffer. I don't like this because then you can't just look at the head of the buffer to see which kind of buffer it is, but to each his own. I suppose you could figure out a way to permanently mark it.
 
Looks like the buffer is beat to snot. Something one would expect to see in a seriously over gassed scenario. Changing the buffer won't correct the over gassing.
 
DUDE!!!!

That buffer is In BAD shape. Lol

I would buy a H3 buffer and try that. I doubt you will have problems with that setup. If you do then swap out 1 weight and you have a H2 to try out. You can engrave "H2" or whatever on the face of the buffer and know what's inside just by cracking the gun open and looking inside

Another option, and prob a better one, would be to go with an adj gas block. With that you can fine tune the gas to optimism function. Some of the adj gas blocks have an " off " position turning the gun into a single shot. This makes for the quietest rifle possible.

I know a full auto with the gas turned off seems oxymoronic, but some gas blocks allow easy and fast changing of the settings. Run the gun full auto, and then if you want to get as quiet as possible....shut off the gas
 
I'm guessing that you're using a lightweight carbine-weight buffer because that's what comes with most buffer system/stock combo packages. A carbine buffer is way too light for your setup; the full-auto and the short barrel don't help, but the biggest thing over-gassing your gun is the silencer. Your BCG is unlocking too soon and slamming way too hard against the back of the buffer tube, and that's why the end of your buffer is all beat up. You need an H2 or an H3 buffer. Not only will a heavier buffer slow down the cyclic rate, making the gun more controllable and greatly reducing parts wear, but it will also lower the amount of gas you get in your face.
Click to expand...

That is very interesting and I like your analysis. Would a Tubb carrier weight system help in delaying the unlock? http://www.davidtubb.com/carrierweight-ar15 I am using them in my match AR15's, but these rifles are full sized AR15's with everything full sized.
 
Thanks fellas. I freely admit that I'm an urban commando. I shoot these guns and share them with people because I enjoy and support the shooting sports. I am not an AR/M16 expert.

Mobuck mentioned that changing the buffer will not fix the overgassing situation. I thought changing out the buffer slows down the bolt, thus holding more of the gas in the chamber and gas tube longer, thereby helping with the overgassing situation. If changing out the buffer tube won't help with the overgassing situation, what will solve that problem?

I don't think I want to go with an adjustable gas tube. Turning the gun into a single shot isn't ideal.

I do run this gun in F/A a lot, just because I like it. That explains the beat up buffer. And in F/A, it runs really fast. It's probably killing the buffer.

I'm going to make my regular range gun another gun after I fix up this M16. I do enjoy the short 11.5 inch barrels, so I'll have to find another 11.5 inch barrel to go with my newly designated range gun. The 16 inch barrel with silencer is too unwieldy.
 
Machineguntony said:
Mobuck mentioned that changing the buffer will not fix the overgassing situation. I thought changing out the buffer slows down the bolt, thus holding more of the gas in the chamber and gas tube longer, thereby helping with the overgassing situation. If changing out the buffer tube won't help with the overgassing situation, what will solve that problem?
Click to expand...
What he means is that you're fixing the symptoms of your problem and not the root cause.

The rifle combined with the silencer is putting too much gas into your system. So the heavier buffer is counteracting that extra gas. But to fix the root cause you need to figure out a way to not have all that extra gas in the first place.

The solution to that is to get an adjustable gas block. I'm not a huge fan of adjustable gas blocks on DI rifles because I've seen a few that didn't work well or managed to adjust themselves. Personally, I prefer the simplicity of just throwing in a heavier buffer. But if you're willing to play around with an adjustable gas block -- and especially if it's just a fun range gun and you're willing to take a chance with durability -- that could be a better overall solution.

Machineguntony said:
I don't think I want to go with an adjustable gas tube. Turning the gun into a single shot isn't ideal.
Click to expand...
The purpose isn't necessarily to ever shut the gas off completely, it's to be able to tune the gas system so it has the optimal level of gas and no more.
 
I'm with you on this, Theo. I'd prefer to keep it simple and just use a heavier buffer. I understand what you're saying. So if I just use a heavier buffer and don't use a gas block, will that damage or put stress on the lower, due to the excessive gas in the system?

If the only cost of excess gas is to put stress on the upper and requiring a regular buffer change, I can live with that. I just don't want stress on the lower.
 
The heavier buffer only delays the cycle but won't reduce the battering of the buffer at the end of the cycle if there's a serious over gassing problem.
Just my opinion but I'm sticking to it.
If you're not tearing rims off, delaying the cycling isn't the answer.
 
Mobuck said:
The heavier buffer only delays the cycle but won't reduce the battering of the buffer at the end of the cycle if there's a serious over gassing problem.
Click to expand...
That's not true at all. A heavier buffer will greatly reduce the battering of the buffer at the end of the cycle since it slows the initial velocity of the carrier and the buffer. Remember, when you have the proper weight buffer the gas pressure has dropped significantly by the time the bolt unlocks.
 
The use of suppressors on rifles creates yet another dynamic in firearms design that is not commonly understood or communicated. Consider the suppressor on a firearm the same as a muffler on a car. The suppressor works as a filter for the gas (noise) that is escaping the barrel during firing. As a “filter”, it takes longer for the gas to leave the confines of the firearm, and thus, it creates back pressure. This back pressure, ESPECIALLY in a gas operated firearm forces an extensive amount of gas back through the firearm’s operating system that may create too much thrust too early during the firearm’s cycle of operation.

To counteract this back pressure, the use of an adjustable gas system is advised. By metering the gas system to ensure that it will cycle the firearm correctly and not flood the system with gas/pressure, the gun will work properly and will still benefit dramatically from the increased velocity potential of Superformance ammunition.
Click to expand...
http://www.hornady.com/ammunition/superformance-in-gas-operated-firearms
 
"Remember, when you have the proper weight buffer the gas pressure has dropped significantly by the time the bolt unlocks."

That debate can rage for days. I doubt the milliseconds that the heavier buffer delays cycling will make so much diff if the extractor isn't tearing rims as run currently.
 
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