AR-15 Possibly Overgassed

[Dolomite_supafly]

A heavier buffer will not prevent the bolt from unlocking while the pressure in the barrel is still high but an adjustable gas block will. If you are running a suppressor most of the time I would tune it for it. A properly gassed gun has less felt recoil, less crud in the receiver, less crud in the face as well as less wear and tear on the gun.

You could also look at getting a MicroMOA gas block. The can be had with up to three positions. Have them make it with .050" on two holes then drill them out for unsuppressed and suppressed.

Or get a click adjustable block and count clicks.

[Oh Shoot]

A heavier buffer will not prevent the bolt from unlocking while the pressure in the barrel is still high ...

 

Seems to me a heavy buffer would have to delay unlocking just as a heavy slide on a blow back pistol does? Or a heavier spring would do same, seems?

 

Sure are lots of other folks who think so too, just for the record. :) :
 

https://www.google.com/search?q=ar+15+heavy+buffer+delay+unlock&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb

 

Including Windham Weaponry, who makes ARs?

 

By increasing dwell time, it delays unlocking of the bolt thereby reducing stress on the extractor/case rim.

 

http://www.windhamweaponry.com/shopexd.asp?id=275#ixzz32JGuVn4u
 

- OS

[molonlabetn]

Seems to me a heavy buffer would have to delay unlocking just as a heavy slide on a blow back pistol does? Or a heavier spring would do same, seems?

Sure are lots of other folks who think so too, just for the record. :) :

https://www.google.com/search?q=ar+15+heavy+buffer+delay+unlock&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb

Including Windham Weaponry, who makes ARs?

http://www.windhamweaponry.com/shopexd.asp?id=275#ixzz32JGuVn4u

- OS

Heavy or light, a carrier will start moving at the same time for a given gas tube length... The difference is how quickly the carrier accelerates. There is some small difference in the time it takes to rotate the bolt, because of that, but not an appreciable difference.

[Dolomite_supafly]

A heavier buffer or spring will reduce the bolt speed. It also masks the problem of being over gassed. The barrel will still have a high level of pressure that will escape when the bolt unlocks early.

Using a standard buffer and a properly gassed system will reduce felt recoil compared to just adding a heavy buffer alone.

There are a lot of manufacturers out there that seriously have no clue. Look at all the over gassed guns on the market. The heavy weight buffers are what they came up with to try to mitigate some of the effects when a properly gassed gun is better.

[Oh Shoot]

Heavy or light, a carrier will start moving at the same time for a given gas tube length... The difference is how quickly the carrier accelerates. There is some small difference in the time it takes to rotate the bolt, because of that, but not an appreciable difference.

 

Well, since the whole cycle takes less than what, .5 sec?,  seems anything that slows down the bolt unlocking at all would be "appreciable", even if just a few ms?

 

A heavier buffer or spring will reduce the bolt speed. It also masks the problem of being over gassed. The barrel will still have a high level of pressure that will escape when the bolt unlocks early.

Using a standard buffer and a properly gassed system will reduce felt recoil compared to just adding a heavy buffer alone.

There are a lot of manufacturers out there that seriously have no clue. Look at all the over gassed guns on the market. The heavy weight buffers are what they came up with to try to mitigate some of the effects when a properly gassed gun is better.

 

I certainly don't disagree that many if not most manufacturers produce over gassed guns, and the reason is obvious, as you have often said -- most overgassed guns will still run okay with any ammo while running closer to true spec can cause short stroking with weaker ammo.

 

And of course an adjustable gas block is the best way to tune an AR for various power loads, even if the gas port is in true spec to begin with, no argument with that at all.

 

But on the other hand, for real world average use, if the user problem is a gun so overgassed that he's damaging or even tearing through cartridge rims and throwing casings at 1:00, or overriding picking up the next round, and a heavier buffer and/or spring alleviates those problems, that really is a  simple and inexpensive "fix" as I see it. Even using heavier buffer for less perceived snap or "recoil" has a benefit too (I did it with my pistol, even though wasn't having any problems to begin with).

 

Yeah, I know you may still be accelerating wear even after doing that, and likely running the rifle dirtier than necessary, but you know, that's really splitting hairs at that point for the long term. And of course, anyone with an A2 sight base block is gonna have to do some significant work, whereas a buffer and/or spring change is a snap.

 

On a similar topic, does that adjustable gas tube you mentioned really work reliably, seems like the adjustment at that level would have to be incredibly precise?

 

- OS

[molonlabetn]

Just from F=ma perspective, at a given input force (gas pressure) the difference in bolt/buffer mass would have to change by a far more significant percentage than going from a car to h2 buffer, to change unlock time significantly, since acceleration to velocity is a root... (ie, a 1oz change in buffer or spring weight is barely 10% of the total inertia, which would be barely a 3% change in bolt speed... I apologize for not showing my work...)

ARs run best with the lightest buffer that will pick up a cartridge, once enough gas is introduced to accelerate the carrier enough to fully compress the buffer spring. Edited May 21, 2014 by molonlabetn

[Dustbuster]

Discussed this w dolomite and used JP and bte adj gas blocks. Problems solved after spending time tuning the guns, I also changed extractor springs to wolf springs and added rubber d rings. My stuff runs fine as frog hair. It took some work but am happy w it.
Gunsmith I recommend:
tony at Maximus arms in Franklin. He knows class 3 stuff very well, is fairly priced and backs up his work. Gets on stuff ASAP and doesn't dick around.
Hole this helps


Sent from my iPhone using Tapatalk 2 of course it ate my spelling.

[Oh Shoot]

Just from F=ma perspective, at a given input force (gas pressure) the difference in bolt/buffer mass would have to change by a far more significant percentage than going from a car to h2 buffer, to change unlock time significantly, since acceleration to velocity is a root... (ie, a 1oz change in buffer or spring weight is barely 10% of the total inertia, which would be barely a 3% change in bolt speed... I apologize for not showing my work...)

ARs run best with the lightest buffer that will pick up a cartridge, once enough gas is introduced to accelerate the carrier enough to fully compress the buffer spring.

 

Convinces me ... but of course high school algebra dropped me from the honor roll a year in high school and I had to really book for the one math course I had to take in college while even the easy A type jocks breezed through it. :)

 

edit: but meant to still emphasize, that there are ARs that just won't run reliably as first configured, but will with a heavier buffer and/or spring, so the bolt unlock is just part of the equation between success and failure in the overall timing. Also throw in the fact that an extractor upgrade (heavier spring and possibly o-ring addition) will also "fix" some to run reliably also.

 

- OS

Edited May 21, 2014 by Oh Shoot

[Ted S.]

....I do like not having to  clean as much gunk out of the gun, and it's also nice not seeing glitter all over the bolt carrier and  from fragmenting casings......

[Oh Shoot]

....I do like not having to  clean as much gunk out of the gun, and it's also nice not seeing glitter all over the bolt carrier and  from fragmenting casings......

 

I've been lucky I guess, got 3 rifles, one SW barrel and two with PSA's FN made ones, and pistol with whatever J&T uses, all with A2 blocks, and all four will shoot bottom rung .223 to NATO 5.56 no probs. And I do like not having to change settings or anything, so haven't much cared about any finer tuning to see if they might run a bit cleaner or whatever.

 

Even the pistol that I put the heavier buffer in didn't change what was already a reliable shooter with good ejection pattern, and not really sure it made any appreciable difference in feel, been meaning to swap buffers back and forth sometime to really see if I can tell a diff.

 

- OS

[molonlabetn]

I can swap between a CAR, H, H2 & H3 and feel the difference, even though the recoil impulse is the same for a given cartridge and gas setting... Adding weight decreases bolt rearward acceleration and forward acceleration; and adding more spring tension increases bolt rearward deceleration and forward acceleration. So, a light buffer and weak spring will pick up rearward speed quickly, and not be slowed down much before bottoming out, then rebound at a moderate pace back to battery. A heavy buffer and weak spring will pick up rearward speed slowly, but not be slowed much before bottoming out, then rebound slowly back to battery. A heavy buffer and heavy spring will pick up rearward speed slowly, and be slowed significantly before rebounding to battery at a moderate pace. A light buffer and heavy spring will pick up rearward speed quickly, but slowed down significantly before rebounding to battery very quickly.

[Ehunt]

On 12/22/2013 at 8:54 PM, Oh Shoot said:

Assuming everything else is up to snuff, earlier than 3:00 ejection pattern does indeed suggest significant overgassing.  Dunno exactly regarding the casing dimples though.

 

So, confused about the adjustable gas block, are you using one or not?

 

edit: okay, see you answered that while I was typing.

 

- OS

 

On 12/22/2013 at 9:11 PM, Oh Shoot said:

Sorry about that, put so much thought into writing the first post that I forgot to mention about the gas block, that's why I went ahead and replied. I didn't want to confuse anyone who may already be reading it too much.

 

The one currently on there is the standard A1 style gas block/iron sight. Sorry about the confusion once again.

 

A heavy H3 carbine buffer might compensate enough to tame it down into spec, but yeah, an adjustable block undoubtedly offers the most control.

 

And sure, a combination of rifle buffer and Russian ammo may have run just about right before on your rifle. Rifle buffer is a bit heavier than even H2 carbine buffer. I shoot a lot of Russian steel, and find it quite satisfactory, but none that I tested has ever hit 3000 fps, so it's underpowered compared to military spec 5.56 or hotter commercial .223.

 

- OS

 

On 12/22/2013 at 11:28 PM, Oh Shoot said:

.....but I don't think it's the solution for a simple overgassed port.

 

Half the ARs out there come with with biggest port possible within the (debatable) specs and are overgassed to some extent, as the manufacturers want to make sure they run period.

 

What, though,  is your solution for an oversized port, though, if not heavier buffer/spring, or often best, adjustable gas block? Weld it up smaller? What's the difference, you're making the aperture smaller before the gas tube either way. Buy a new barrel?

 

When you get one that is so overgassed that it's throwing empties out at 1:00 and overrides the mag to where it doesn't even pick up the next round, and you put an adjustable block on it so that it slings them at 4:00 and runs 100%, I'd call the thing fixed, myself.

 

- OS

I have the same thing happening with my 8.5" pistol. Being that my barrel is much shorter, I am thinking an H3 Buffer and a stronger spring will bee what's needed to correct the over gassing?

[Oh Shoot]

16 hours ago, Ehunt said:

 

I have the same thing happening with my 8.5" pistol. Being that my barrel is much shorter, I am thinking an H3 Buffer and a stronger spring will bee what's needed to correct the over gassing?

If overgassing is truly the prob, then yes would likely help, though it's a band-aid, where an adjustable gas block would be a cure.

Depending on exact symptoms (you quoted a bunch of stuff so not sure which one),  another very common fix is to beef up the extractor (if didn't come that way) with extra power spring and/or o-ring. (short dwell time not allowing cartridge to shrink back down so that normal spec extraction fails).

- OS

[Ehunt]

1 hour ago, Oh Shoot said:

If overgassing is truly the prob, then yes would likely help, though it's a band-aid, where an adjustable gas block would be a cure.

Depending on exact symptoms (you quoted a bunch of stuff so not sure which one),  another very common fix is to beef up the extractor (if didn't come that way) with extra power spring and/or o-ring. (short dwell time not allowing cartridge to shrink back down so that normal spec extraction fails).

- OS

I cited three quotes because I am experiencing 1:30 ejection, damaged brass, and considering the heavy buffer and buffer spring to help. I was going to try them with an adjustable gas block. I have a Sharps Rifle Company BCG, so it is quite stout, however I can replace the extractor spring as I have one from a previous order from SprinCo.

I ordered a SprinCo RED Buffer Spring (see link below), an EXPO Arms H3 buffer, and a Superlative Arms adjustable gas block.

My question is this: should I use all three parts (Adjustable Gas Block, H3 Buffer, and SprinCo RED Buffer Spring) together, or is the Adjustable Gas Block enough to solve the over gassing on its own?

 

Link to RED Buffer Spring: https://bkingsfirearms.com/shop/ar15-spare-lower-upper-parts/tactical-springs-sprinco-buffer-action-springs-ar15-ar10-and-lr308/

Edited November 12, 2018 by Ehunt

[Oh Shoot]

19 minutes ago, Ehunt said:

.... I was going to try that before getting an adjustable gas block, mostly due to expense. ....

I ordered a SprinCo RED Buffer Spring, and an EXPO Arms H3 buffer from Primary Arms. I am hoping this will do the trick. If not, then I'll have to get the adjustable gas block......

I did get a Superlative Arms adjustable gas block Faxon Firearms has them on sale right now. ...

You have a confusing way of putting things, ya know.

19 minutes ago, Ehunt said:

My question is this: should I use all three parts (Adjustable Gas Block, H3 Buffer, and SprinCo RED Buffer Spring) together or is the Adjustable Gas Block enough to solve the over gassing on its own?

IF you indeed have an adjustable gas block, I'd go with that, since that's what they are for.

- OS

[Ehunt]

1 hour ago, Oh Shoot said:

You have a confusing way of putting things, ya know.

IF you indeed have an adjustable gas block, I'd go with that, since that's what they are for.

- OS

Sorry, I tired to edit that out. Thanks for your help.

[Ehunt]

On 11/11/2018 at 9:00 PM, Oh Shoot said:

You have a confusing way of putting things, ya know.

IF you indeed have an adjustable gas block, I'd go with that, since that's what they are for.

- OS

Used a gas block and "tuned" it to where it would lock open with an empty mag. It was still ejecting too far forward (2:15). I added the H3 Buffer and SprinCo Heave (RED) buffer spring. This did the trick! It is ejecting at 3:00 now and functioning perfectly!