Gas Gun Techniques???

[taliv]

Re: Gas Gun Techniques???



read this: http://sadefensejournal.com/wp/?p=1093

note the pressure they measured when the bullet exited the bore.

are you seriously contending that that "puff of smoke" is more than 5700 psi?? cause that's what it would have to be if the bolt unlocked before the bullet left the barrel.


of course pistol barrels move before they bullet exits the barrel. they are recoil operated, duh. the barrel starts moving at the same time the bullet does. http://www.youtube.com/watch?v=KfaqwxFpzGg

 

[taliv]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Captain Kirk</div><div class="ubbcode-body">

A AR style bolt rotates and unlocks before the bolt carrier can move rearward. I think a slow motion video of the action with a view of the exiting projectile will put this to rest.

</div></div>

uhh, no. the gas acts on the carrier, moving the carrier back, which causes the cam pin to rotate the bolt unlocking it. you can see this easily simply by pulling the charging handle and observing.

 

[Lowlight]

Re: Gas Gun Techniques???

Dude the problem is, everyone looks at when the brass comes out and not when the BCG begins to move, there is movement there before it unlocks, and my point is how much the gas passes the bullet which is where you get the bleed off, the fact the bullet increases that when it passes the gas block is not the issue, the issue is you have gas passing the bullet which bleeds it off to huge degree.

Even in a handgun, if you watch the video, and is part of my point, the brass "exits" the chamber when the bullet is long gone, but clearly the system is moving. Same thing here...

The brass and bolt will unlock after, but it starts moving first.

 

[taliv]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Look at the video and watch how much, more, and how much faster the gas leaves the barrel before the bullet, even with a short barreled handgun. </div></div>

sure, but that handgun bullet will only ever be about 800-1300 fps. the gas is traveling 5x as fast as that bullet. however, the gas behind a 220swift is only going maybe 1.2x faster.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
The gas passes the bullet... the delay unlocking is from the distance the BCG has to move to actually unlock the lugs, not because the bullet is 15ft past the muzzle, that is insane.

The bullet doesn't start at 2600ft, it ends up there, the gas speed is much faster from the start. It takes time to reach that speed over 20" the gas is much faster.

</div></div>

the delay is from adding weight of the carrier, bolt, buffer and the force of the action spring, all of which slow the carrier down. sure the gas gets there fast, but it has to build up pressure in the carrier to move it. that's why you can slow down the cyclic rate by using a heavier carrier, or an H, H2, H3 buffer.

think how little extra weight (H to H2) is required to slow the unlocking of the bolt.

the added weight is needed with suppressors because the suppressor keeps the system pressurized longer, and the weight slows the bolt from unlocking, giving the system extra time to reduce pressure to less annoying levels. (giving the brass time to shrink back from the walls of the chamber)

 

[Lowlight]

Re: Gas Gun Techniques???

You guys don't understand english apparently...

I never once said the BOLT UNLOCKS, I said the BCG Begins to move before it unlocks the bolt from the chamber. That movement happens with the bullet in the bore.

How does a 308 get a last round deviation when you empty the magazine if the bullet was long gone ? We see it all the time, the last round in the magazine will impact different than the others... explain that phenomenon ?

 

[taliv]

Re: Gas Gun Techniques???

"there is movement there before it unlocks,"

yep, i agree. recoil moves the bolt, not the gas. recoil pushes the bolt back against the barrel extension and moves the whole gun. and there is typically more play between the bolt / barrel lugs in a gas gun.

 

[elfster1234]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MistWolf</div><div class="ubbcode-body">
Studies by the army show that the bullet fired from an M14 is several feet down range before the reciprocating mass of the action even begins to move. The gases in the AR have even further to travel before reaching it's piston.
</div></div>

I'm sorry mistwolf, but I need to call you out on this one. Show me this study <span style="font-weight: bold"><span style="text-decoration: underline">with</span></span> a crazy slow mo video with the bullet even 1 foot out of the barrel without the action moving one single bit and I'll shut my mouth and eat my words & will take back everything I've said so far.

 

[Lowlight]

Re: Gas Gun Techniques???

There is also a preload in the gas tube, some of that gas, in the barrel that passes the bullet will escape up the gas port, because it is the first exit before leaving the barrel.

That pre-load on the gas tube has value, and time... heavier BCG does slow it down, but that doesn't mean it is not moving from the gas, maybe not enough to unlock, but enough to start the process.

The bolt carrier moves... Try shooting and not crunching numbers and you can see the results, like the last round deviation. Recoil moves the whole rifle, the more recoil the tighter it lock into the lugs, the BCG is the only way to unlock it, not recoil.

 

[Captain Kirk]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: taliv</div><div class="ubbcode-body">
uhh, no. the gas acts on the carrier, moving the carrier back, which causes the cam pin to rotate the bolt unlocking it. you can see this easily simply by pulling the charging handle and observing.
</div></div>

I missunderstood you, I thought you meant the bolt was already moving rearward (bolt fully unlocked and bolt carrier moving rearward) which would be the other extreem of what is being discussed. What Lowlight is saying ^^ is how I always understood the function of the gas system/bolt, if you remove or close off the gas system, the gun will not cycle. Would the bolt move rearward from recoil alone or is the gas required to unlock the bolt before the carrier can move (?)

 

[elfster1234]

Re: Gas Gun Techniques???

hell, i bet someone on snipershide got to have a <span style="font-weight: bold"><span style="text-decoration: underline">.308 AR-10</span></span> type rifle that can take some crazy slow mo video showing a nice side view of bullet in flight with the action moving.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: elfster1234</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MistWolf</div><div class="ubbcode-body">
Studies by the army show that the bullet fired from an M14 is several feet down range before the reciprocating mass of the action even begins to move. The gases in the AR have even further to travel before reaching it's piston.
</div></div>

I'm sorry mistwolf, but I need to call you out on this one. Show me this study <span style="font-weight: bold"><span style="text-decoration: underline">with</span></span> a crazy slow mo video with the bullet even 1 foot out of the barrel without the action moving one single bit and I'll shut my mouth and eat my words & will take back everything I've said so far. </div></div>

 

[Mike_in_FL]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: taliv</div><div class="ubbcode-body"> and the weight slows the bolt from unlocking, giving the system extra time to reduce pressure to less annoying levels. (giving the brass time to shrink back from the walls of the chamber) </div></div>

Which is the "how" of Tubbs' carrier weight system working without tweaking the gas sytem. The gas is inducing a velocity/acceleration to the carrier. If you want to know where the bullet IS at X time you would have to be able to time it from ignition to a known distance to chronograph. You need to work the acceleration from velocity and get your numbers at pertinent distances in the system. Then, if what I have read is true, use the 550 microsecond lock time of the rifle gas system.

That's what you're looking for if that's all it takes to get the carrier to move and disconnect from the gas tube. Where is the bullet 550 microseconds after passing the gas port?

EDIT: I don't know the true definition of lock time either. That is, I can't tell you if the quoted value is 550 microseconds after ignition, or bullet passing gas port.

 

[Lowlight]

Re: Gas Gun Techniques???

And you are missing a key point of interest in your graph... that is bore pressure with a 556, take a 308 which has that much powder burning.

And that chart is at the muzzle on exit, take a 20" 308 which needs more pressure to move a 175gr bullet then give the gas a 7" head start... Again, right numbers in the wrong place to prove a point, so you sound and look official.

At 13" the bullet is not going 2600fps, and yet at your gas exit, it shows higher pressure at 14.5", it can easily be 10k psi at the gas port while the bullet might just be reaching 2000fps ... see the difference. give it that head start and the BCG is moving .

 

[Mo_Zam_Beek]

Re: Gas Gun Techniques???

Taliv - you're talking past LL. Read these two quotes carefully: (emphasis added by me)


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">You guys don't understand english apparently...

I never once said the BOLT UNLOCKS, I said <span style="font-weight: bold">the BCG Begins to move before it unlocks the bolt from the chamber</span>. That movement happens with the bullet in the bore. </div></div>



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: taliv</div><div class="ubbcode-body">"there is movement there before it unlocks,"

<span style="font-weight: bold">yep, i agree. recoil moves the bolt,</span> not the gas. recoil pushes the bolt back against the barrel extension and moves the whole gun. and there is typically more play between the bolt / barrel lugs in a gas gun. </div></div>


Good luck


ETA - someone is going to have to get their calculator out and prove forces vectors but on face it is a different game - explosion + the weight of the bolt = bolt wiggle vs the weight of the BCG + spring force + buffer weight + X pressure = BCG movement.

To the casual observer (me) it is hard to fathom that the first substantive movement is the movement imparted on the bolt by the explosion. Logically if it were the primary force, it alone would be the most responsible for unlocking the lugs. That is not my understanding of how the gas system works.

 

[LoneWolfUSMC]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: finbox</div><div class="ubbcode-body">On my DPMS 6.5 CM the bolt is moving before the bullet is leavening the barrel.</div></div>

This is not an accurate test of your hypothesis. There are way too many variables.

The simple test is to run a high speed camera on it. Unfortunately I have not been able to fund that project yet.

 

[Lowlight]

Re: Gas Gun Techniques???

I am gonna talk to someone here about getting a high speed Phantom I know where to get access to one local

 

[CoryT]

Re: Gas Gun Techniques???

Newton was not wrong. As soon as the bullet begins to move, energy is being delivered in the opposite direction. As the bolt is locked into the barrel extension, that force is transmitted as recoil. Since the mass of the rifle is much larger than the mass of the bullet, the movement of the rifle is much slower than the bullet.

The bolt carrier begins to move well before the bullet exits. The system is timed so that the bolt does not unlock until the bullet has left the bore and pressure has dropped to a safe level. However, a much larger mass has be put in motion. Having done plenty of high speed video for Gun Stories, I've quite clearly seen the gun begin to move before the bullet has left the bore.

 

[MistWolf]

Re: Gas Gun Techniques???

Tell the Army they are wrong. It's their report.

The part I left out is that the 2750 is what's listed for velocity from an M14 with a 22" barrel according to some sources. Yes, it's about as accurate as any other manufacturer's claim. The point is, the bullet is travelling down the bore even slower than most 5.56 ammo. If the US Army- let me say that again- if the US Army has found that the bullet from an M14 has exited the muzzle before the gas causes the gas piston to move, it should be correct.

The problem here is many pass off the information they read on the internet without thinking what that means, as factual. What is the port pressure of a M4? Around 10k? (You can look it up). What do you think the consequences of extracting an empty case from the chamber would be if pressures were still thousands of psi?

As far as the small puff of air, I never said "while shooting suppressed" did I? The fact that there is greater pressure coming out of the action from shooting suppressed proves that it comes because the suppressor delays blow down, not because the bolt unlocks while the bullet is still in the bore. If the bullet was still in the bore while the action was working, the bullet would be at the same spot, with or without suppressor and be in the same spot when the gas key separated from the gas tube and the amount of gas would be the same and BCG velocity the same.

But it's not

 

[MistWolf]

Re: Gas Gun Techniques???

From Armalite's Tech Bulletin dated July 3, 2010
<span style="font-style: italic">There is a common belief that the external piston operated systems are less accurate than the Stoner internal piston system because the operating parts start moving while the bullet is still in the bore. This is not true: Army Ordnance tests conducted in the 1960s revealed that the bullet is 25 feet out of the bore of the M1 and 15 feet out of the bore of the M14 before any operating part begins to move. It is more likely that the imbalances of the external piston, operating rod, cylinder, and other parts hanging on the barrel produce disruptive vibrations as the bullet exits the bore</span>

http://www.armalite.com/images/Tech Notes/Tech Note 54, Gas vs Op Rod Drive, 020815.pdf

 

[LoneWolfUSMC]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">I am gonna talk to someone here about getting a high speed Phantom I know where to get access to one local </div></div>

I know where to get one. I just can't afford to rent it for the time I need to do the shoot.

 

[Randoman5]

Re: Gas Gun Techniques???

We could all just request more high speed video from Brass Fetcher.

His equipment looks pretty outstanding. Definitely the best high speed ballistics gel video I've ever seen. Everyone should take a look at his 750 grain A-Max .50bmg.

 

[Lowlight]

Re: Gas Gun Techniques???

Reports from the 60's are worthless, you have no practical experience and that is not how it works. They didn't have the technology then and were basing that on the brass ejection, not the movement in the system prior.

 

[Mike_in_FL]

Re: Gas Gun Techniques???

The more I've dug up, the more I believe the system was designed to have the bullet leave before the carrier begins to move much. I'm saying "much" because it only has to go something like .375" before it would vent gas. So if it is moving at all, it may be hard to detect.

This is really a case of two different projectiles traveling in opposite directions and the timing of which one gets there first.

The velocity of the gas in the barrel is much higher than what flows through the gas tube. As long as that gas arrives into the carrier cavity with about 3k psi, the rifle cycles properly. For some of this to make sense I think you have to visualize the gas as definitely having a mass rather than thinking it essentially weight-less.

You push that mass through a small port with a pressure initially around 15k psi. As soon as the bullet leaves the barrel the pressure would begin to drop to zero, however this is insignificant. You already have a mass moving down the tube towards the carrier and it's not going to stop or reverse direction because the force that accelerated it has stopped.

I'm editing now, the 2nd sentence in the paragraph above has a BUT. That holds true as long as the dwell length, that 7" of barrel past the gas port, is the same. If the pressure is not held sufficient for that mass in the gas tube to be accelerated and arrive with 3k psi all bets are off. The rifle will not cycle.

What makes the gun go bang? Obviously something leaving the barrel at supersonic speed. If you had that same gas mass traveling supersonic into the carrier would we not get a bang somewhere there too?

I think the answer has already been observed and mentioned here. When the rifle is fired without the suppressor, you don't detect much if any gas blowing back. Yet it's the opposite with the can, so why?

The only way I can conceive this is happening is because the bullet is still inside the can. The system has to still be sealed somewhat at the muzzle to feel pressurized gas leaving the carrier or bolt. A paper from 1971 was stating they knew then that leakage was occurring from around the rear of the bolt so how could it not leak more under greater pressure?

I think the only way you could stop the blow back into your face suppressed would be to either move the gas port farther down the barrel or if in the same location, decrease the port size. You would probably just have built a rifle that would not run without the can though. Or to do so would require lighter buffer, less powerful spring.

All things being equal in use, round count, a 14.5" M4 should wear parts faster than a 20" M16A4. This being due to the M4 gas port pressure being about double that of the M16 and pressure in the carrier gas cavity being > or = to 4k psi. The guns won't cycle when that pressure is down to 2k psi. The carrier in the M16 moves something like 160"/second and 240"/second in the M4.

In the 1971 tests at APG a .036 gas port wouldn't cycle the gun. With the gas port at .120 it stated the buffer button compressed to the extent that the key was hitting the receiver. Yet, the muzzle velocity was essentially the same with 5 different port sizes.

I still want video though!

 

[MistWolf]

Re: Gas Gun Techniques???

The reason there is more gas in the rifle during extraction when firing suppressed is the can slows the velocity of the gas, increasing the amount of time for the system to blow down. The can becomes a pressure reservoir. Remember, gas has mass as you stated

 

[BCP]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CoryT</div><div class="ubbcode-body">Newton was not wrong. As soon as the bullet begins to move, energy is being delivered in the opposite direction. As the bolt is locked into the barrel extension, that force is transmitted as recoil. Since the mass of the rifle is much larger than the mass of the bullet, the movement of the rifle is much slower than the bullet.

The bolt carrier begins to move well before the bullet exits. The system is timed so that the bolt does not unlock until the bullet has left the bore and pressure has dropped to a safe level. However, a much larger mass has be put in motion. Having done plenty of high speed video for Gun Stories, I've quite clearly seen the gun begin to move before the bullet has left the bore. </div></div>

Yeap. I've seen a few videos as well. The rifle definitely moves before the bullet leaves the barrel.

 

[Mike_in_FL]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MistWolf</div><div class="ubbcode-body">The reason there is more gas in the rifle during extraction when firing suppressed is the can slows the velocity of the gas, increasing the amount of time for the system to blow down. The can becomes a pressure reservoir. Remember, gas has mass as you stated </div></div>

I agree with you. The suppressor slows the gas mass down from that cracking supersonic speed. I'm just not seeing how without the bullet being within the can at that time it's still semi-plugging the system to the same extent. I could be wrong, wouldn't be the first time.

I base this guess on the fact that even within this pressure reservoir the gas velocity should be a greater speed than what is in the gas tube blowing back into the carrier. Suppressor manufacturers feel free to jump in here, lol.

This would be a lot simpler to visualize if you think of water. Of course, some of the crazy equations I've just seen and would never be able to solve state that they're not only applicable to a rifle but also to jet nozzles such as in a turbine using steam (water).

Somewhere, someone knows all this already since we're talking a 50 year old system here. But since you can find tests run using pressure sensors at the gas port and the muzzle, it sure seems to imply that this was "timed", like an engine, to start cycling when the bullet left the muzzle. Therefore, why the 7" dwell length is so important.

 

[finbox]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: finbox</div><div class="ubbcode-body">On my DPMS 6.5 CM the bolt is moving before the bullet is leavening the barrel.</div></div>

This is not an accurate test of your hypothesis. There are way too many variables.

The simple test is to run a high speed camera on it. Unfortunately I have not been able to fund that project yet. </div></div>

http://m.youtube.com/#/watch?v=NMT1leu-bYc&desktop_uri=/watch?v=NMT1leu-bYc

Slowest I could find. I realize its a crude hypothesis. Bullet is WAY faster than the bolt.
Why do groups change on bolt hold shots?

 

[tallhorse89]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">You guys don't understand english apparently...

I never once said the BOLT UNLOCKS, I said the BCG Begins to move before it unlocks the bolt from the chamber. That movement happens with the bullet in the bore.

How does a 308 get a last round deviation when you empty the magazine if the bullet was long gone ? We see it all the time, the last round in the magazine will impact different than the others... <span style="color: #FF0000">explain that phenomenon </span>? </div></div>

Could it be the that a round in the mag holds the bcg in one place(during feeding). and when you take round out there is no upward force on the bcg. basically its the feeding that is different not the extraction? did that make sense? it did in my head.......

 

[sinister]

Re: Gas Gun Techniques???

http://www.youtube.com/watch?gl=US&hl=en&client=mv-google&v=NMT1leu-bYc&nomobile=1

Perfect.

In this one you can even see the gas pulse hitting the vent holes in the bolt carrier before the carrier starts to move:

http://www.youtube.com/watch?v=OzeGPq23veU&feature=relmfu

 

[Mike_in_FL]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">How does a 308 get a last round deviation when you empty the magazine if the bullet was long gone ? We see it all the time, the last round in the magazine will impact different than the others... explain that phenomenon ? </div></div>

If I live 5 more lifetimes you're still going to have shot more of these than I ever will so I put your question back to you. Aren't there exceptions? Do you run into this with the GAPs? POFs? LMTs? Seems like this is a typical event in an FN FAL, but not necessarily a given with all ARs. Is it more prevalent with the .308 than .223 in your experience?

 

[MistWolf]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fngmike</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MistWolf</div><div class="ubbcode-body">The reason there is more gas in the rifle during extraction when firing suppressed is the can slows the velocity of the gas, increasing the amount of time for the system to blow down. The can becomes a pressure reservoir. Remember, gas has mass as you stated </div></div>

I agree with you. The suppressor slows the gas mass down from that cracking supersonic speed. I'm just not seeing how without the bullet being within the can at that time it's still semi-plugging the system to the same extent...</div></div>

It's easy to illustrate for yourself how it work. Blow up a balloon, the release the air inside. It does not flow out instantly, it flows out over time

 

[hk dave]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MistWolf</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fngmike</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MistWolf</div><div class="ubbcode-body">The reason there is more gas in the rifle during extraction when firing suppressed is the can slows the velocity of the gas, increasing the amount of time for the system to blow down. The can becomes a pressure reservoir. Remember, gas has mass as you stated </div></div>

I agree with you. The suppressor slows the gas mass down from that cracking supersonic speed. I'm just not seeing how without the bullet being within the can at that time it's still semi-plugging the system to the same extent...</div></div>

It's easy to illustrate for yourself how it work. Blow up a balloon, the release the air inside. It does not flow out instantly, it flows out over time</div></div>

A balloon is low pressure, non chemical, non violent reaction...

Trying to see how your analogy can be compared or related to a violent chemical explosion, chambered in steel strong enough to contain it.

Aren't these two completely different things?

 

[BasraBoy]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">http://www.youtube.com/watch?gl=US&hl=en&client=mv-google&v=NMT1leu-bYc&nomobile=1

Perfect.

In this one you can even see the gas pulse hitting the vent holes in the bolt carrier before the carrier starts to move:

http://www.youtube.com/watch?v=OzeGPq23veU&feature=relmfu </div></div>

Great clips!

 

[MistWolf]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hk dave</div><div class="ubbcode-body">...Aren't these two completely different things? </div></div>

We are still talking about a pressure vessel. The principle is the same. Gas has mass and mass takes time and energy to move.

That's not to say a suppressor is not filling with pressurized gas while the bullet is inside, but it's not the bullet that slows venting. The bullet still exits before the action begins opening, if the suppressor isn't too long!

Smokeless powder burns rapidly rapidly at a controlled rate which will build to great pressure if contained, but it does not explode

 

[Mike_in_FL]

Re: Gas Gun Techniques???

I'm not disagreeing, but a balloon and a metal suppressor do not seem very analogous. Then again, I never blew into a suppressor, LOL.

 

[MistWolf]

Re: Gas Gun Techniques???

Every time you fire a rifle or handgun equipped with a suppressor, you are blowing into a suppressor.

Just because the suppressor is much less elastic and is charged to higher pressures more rapidly than a balloon, it does not change the fact both need time to vent pressure.

C'mon guys, just because it's rocket science, doesn't mean it's complicated

 

[hk dave]

Re: Gas Gun Techniques???

It's complicated to me.

 

[thejeep]

Re: Gas Gun Techniques???

III. For every action there is an equal and opposite reaction.

In 2012 speak if sh!t is moving foward then other sh!t is moving backward.

 

[freeflight]

Re: Gas Gun Techniques???

interesting topic

 

[Ed-G]

Re: Gas Gun Techniques???

1) Firing pin strikes primer.
2) Cartridge fires with a huge increase in pressure.
3) Bullet moves down the barrel. Gun is moving back and rotating opposite to the barrel twist
4) Bolt is loaded due to pressure and is restrained by the bolt lugs.
5) Bullet travels past gas port but has not left the barrel. During this dwell period gas is released first up the port and then redirected down the tube. The gas velocity is around 4000ft/s

Why is a gas gun tougher to shoot than a bolt gun.
1) Gas gun uses a rotating hammer to move the firing pin. Bolt gun uses a spring inline with the bore.
2) Gas gun has a bunch of loose parts that "wiggle" when the bolt is thrust back on pressure build. These include the bolt carrier, buffer and buffer spring.
3) Gas gun has a carrier that "wiggles" when the pressure rises in the gastube.
Note: items 2 & 3 have not started cycling but they are "wiggling".

1, 2 & 3 is why gas guns are tougher to shoot than bolt guns.