Auto Gas Plug

[Rich 3]

Closing the bleed hole wouldn't matter. It can only bleed after the action has already cycled.

 

 

That makes sense, I may be the victim of some bad advice.

[Guns Are Great 140]

Well I love the idea of the auto regulator!

Anybody using the auto adjusting gas plug that is being sold by CSS. The idea of not having to remember to change the plug every time I change loads would be great, (the memory is one of the first things to go).

 

 

[BobAsh 582]

Tony posted it but it's not his work. If I recall correctly, the 12" was the best compromise between speed and short-ness.

 

The cycling pressure bleed is not going to affect velocity.

 

Also I don't want anyone to get the idea I was dissing this product. It's a good idea and as far as I can see it works as advertised for a lot of guys. I just tend to speak like an engineer.

[Bean.223 365]

I'll be getting one in a few weeks, I'll have to leave a report!!

[RJWesleyIII 7]

Does anybody have the measurement on the total length, and the length of the part of the plug after its screwed in? The part that sticks out?

[weissfe 3]

I own the Autoplug and I love it. But I can personally attest to the fact that it can't overcome the need for a break in period. I had to run at least 200+ rounds of high powered buck and slug before I was able to get the Autoplug to run with Wallyworld Remington bulk pack.

[Gunfixr 76]

Like BobAsh has said, no plug will give the gun more gas than the factory plug. Only so much will come through the ports, and last so long depending on barrel length and where the ports are in relation to the muzzle.

All the various plugs do is close off part of the gas, let it all through, or bleed off some. The shape of the puck end will have some effect on how it flows to the puck, even though it cannot bring more to the puck than the ports will allow through. This channeling can improve function, but only to the limit of the gas amount. If the gun does not have enough gas flow (undegassed), then no plug will make up for that. I said all that years ago, nothing has changed.

Also, as BobAsh said, the bleed port at the back of the gas block has nothing to do with function. During normal cycling, the puck moves rearward, pushing the bolt carrier, until it is bottomed out at the far end of the gas block. The bleed port simply allows any gas escaping past the puck to flow out, as well as ensuring that there is no back pressure building behind the puck as it travels rearward, since the carrier piston head blocks most of the hole it travels through.

As for the ETAC plug, while the "spinning" action is possible, I doubt it happens much, if at all. The reason is simple. The puck travels less than 1/2" longitudinally during function. That's just not enough for any appreciable spinning motion to happen. However, it does give more crud room, which doesn't hurt. The bad part, however, is that it makes for a slightly larger gas chamber. The gas chamber is the area between the plug and the puck. This space must be filled with the expanding gases before puck movement starts. Since there will only be so much expanding gases available, too much chamber will effectively undergas the gun. Since the rotational cuts in the sides of the ETAC puck go to the front, all of that area must be filled as it becomes part of the gas chamber. A flat faced puck reduces the gas chamber. A smaller gas chamber can make a barely undergassed gun run, as less gas is then required to move the puck. I made an experimental gas puck with a chamber in its face to collect crud, and it shut down an otherwise working gun, even though it was tighter in the gas block, having a better seal.

[BobAsh 582]

The bad part, however, is that it makes for a slightly larger gas chamber. The gas chamber is the area between the plug and the puck. This space must be filled with the expanding gases before puck movement starts. Since there will only be so much expanding gases available, too much chamber will effectively undergas the gun. Since the rotational cuts in the sides of the ETAC puck go to the front, all of that area must be filled as it becomes part of the gas chamber. A flat faced puck reduces the gas chamber. A smaller gas chamber can make a barely undergassed gun run, as less gas is then required to move the puck. I made an experimental gas puck with a chamber in its face to collect crud, and it shut down an otherwise working gun, even though it was tighter in the gas block, having a better seal.

 

 

This is a great point, I hadn't thought of that mainly because I've never seen one installed.

 

But yeah, increasing that chamber with either the "cutting" legs or dished piston face is going the wrong direction reagrding gas pressure, especially when you consider the small cycle time.

[RJWesleyIII 7]

So a bigger flat faced puck would be ideal? Is there such a part?

[Mephis 82]

When looking at pucks I would view it the same way as a piston in a car.

 

If you want to raise compression, you reduce the combustion chamber size. Usually by domed pistons.

 

 

I wonder why no one has made a "domed" puck for the saiga 12? I'd think the science behind a piston in a car engine and the puck in a saiga 12 would be practically identical, except there's less force involved so there's no need for rings to completely seal the puck, since it'd create drag and prevent it from working.

 

I'd think a puck that was loose enough to move freely with a slightly domed face would drastically improve a low-gassed gun. But since this doesn't exist, it makes me wonder if I'm being stupid or if someone just hasn't thought to do it yet(which seems unlikely).

[RJWesleyIII 7]

When looking at pucks I would view it the same way as a piston in a car.

 

If you want to raise compression, you reduce the combustion chamber size. Usually by domed pistons.

 

 

I wonder why no one has made a "domed" puck for the saiga 12? I'd think the science behind a piston in a car engine and the puck in a saiga 12 would be practically identical, except there's less force involved so there's no need for rings to completely seal the puck, since it'd create drag and prevent it from working.

 

I'd think a puck that was loose enough to move freely with a slightly domed face would drastically improve a low-gassed gun. But since this doesn't exist, it makes me wonder if I'm being stupid or if someone just hasn't thought to do it yet(which seems unlikely).

 

Thats a good way to look at it Maybe I should try to weld some material on a cheap stock puck and do some testing Whats the worse that could happen, be out a few bucks for a stock piston?

[HotShot308 11]

When looking at pucks I would view it the same way as a piston in a car.

 

If you want to raise compression, you reduce the combustion chamber size. Usually by domed pistons.

 

 

I wonder why no one has made a "domed" puck for the saiga 12? I'd think the science behind a piston in a car engine and the puck in a saiga 12 would be practically identical, except there's less force involved so there's no need for rings to completely seal the puck, since it'd create drag and prevent it from working.

 

I'd think a puck that was loose enough to move freely with a slightly domed face would drastically improve a low-gassed gun. But since this doesn't exist, it makes me wonder if I'm being stupid or if someone just hasn't thought to do it yet(which seems unlikely).

Thats a good way to look at it Maybe I should try to weld some material on a cheap stock puck and do some testing Whats the worse that could happen, be out a few bucks for a stock piston?

Something to consider along this line of thinking... A piston in an internal combustion engine is connected to a connecting rod.

The dome in a domed piston is shaped in a way that it "fits" the shape of the combustion chamber in the head.

State another way, this achieves greater compression by reducing the size of the combustion area by making the top of the piston fit into the domed area in the head.

 

The puck is not connected to anything, and the plug is usually flat faced except for angles to adjust the gas opening. I was just looking at my stock plug today, it is flat.

 

Taking this into consideration, making a domed puck would be counter productive, as the plug is not domed, rather it is primarily flat..therefor already having the smallest available volume (think combustion chamber) until the gas charge starts to push it back.

 

In stock form it probably makes contact when being driven forward by the bolt carrier returning the bolt into battery, but it probably is not actually pushing it against the plug or there would be a possibility of not letting the bolt completely close. With a flat face, however, the contact area is spread out, and little to no wear/damage occurs.

 

The only 2 ways you could make a domed puck would be to reduce the overall height of the puck by trimming around the front circumference, or adding to the face of it.

 

If material is added, it could create a situation the creates excessive wear or damages parts in the gas system, or bolt carrier, similar to an over-gassed gun damaging the trunnion, but occurring at bolt close instead of during the ejection/charge cycle.

 

In either case, since the puck is not connected to anything, it would create a smaller contact point, creating a wear surface at the peak of the dome against the gas plug. Also not good.

[gunfun 3,931]

Tony posted it but it's not his work. If I recall correctly, the 12" was the best compromise between speed and short-ness.

 

The cycling pressure bleed is not going to affect velocity.

 

Also I don't want anyone to get the idea I was dissing this product. It's a good idea and as far as I can see it works as advertised for a lot of guys. I just tend to speak like an engineer.

 

 

Any chance you know where I could find this data? I'd love to at least archive it on my pc for personal reference. I just had a lib conlaw professor say that part of the justification for 1934 NFA act used to support the MIller decision was that SBS shotties were abnormally dangerous due to extreme spread. It would be handy to offer more than my recollection and personal experience with an AOW as a counterpoint. Plus since questions about the effects of SBS come up in new guy inquiries every few months, it would be helpful as a reference to keep from misstating the facts as memory becomes more distant. (as has happened by me in this thread already.)