Gas Gun Techniques???

[308Shooter1911]

Since I have started researching semiautomatic gas guns I have heard several of you mention that the techniques for gas guns and bolt guns are different, Several of you mentioning that it is more difficult to shoot a precision semi automatic gas gun than it is to shoot a precision bolt gun. How do these techniques differ?

 

[KillShot]

Re: Gas Gun Techniques???

The follow-through with a gas gun is very important. A gas gun isn't as forgiving as a bolt and will reveal poor shooting technique/form.

There's a video in the Sniper's Hide Online Training in which Lowlight addresses/demonstrates on driving a semi-auto .308.

 

[308Shooter1911]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KillShot</div><div class="ubbcode-body">The follow-through with a gas gun is very important. A gas gun isn't as forgiving as a bolt and will reveal poor shooting technique/form.

There's a video in the Sniper's Hide Online Training in which Lowlight addresses/demonstrates on driving a semi-auto .308. </div></div>

Really? I did the Snipers Hide training and don't remember that...Thanks

 

[Temp9]

Re: Gas Gun Techniques???

In my experience, the techniques are pretty similar. Gas guns, though, are much more picky, especially trigger control and followthrough. It becomes very obvious with a gas gun if I'm having an off day.

 

[deadly0311]

Re: Gas Gun Techniques???

You have to deal with 3 different recoil pulses on the gas gun where the bolt gun has one. Gas guns are a little harder to shoot because if your follow through isn't spot on and body position is out of whack, you will definitely notice these deficiencies down range.

 

[308Shooter1911]

Re: Gas Gun Techniques???

So...Is it safe to say that practice on a gas gun will make you that much better on a bolt gun.

 

[LoneWolfUSMC]

Re: Gas Gun Techniques???

Yes and no.

Practice on a gas gun can improve your follow-through. It isn't going to improve your speed and technique in operating a bolt rifle (which is very important in competition).

On the other hand, practice on a long barreled match .22LR can improve your follow through on center fire rifles. More barrel time makes follow through critical.

 

[DavidAR10]

Re: Gas Gun Techniques???

I've never experienced different "riding techniques" in 20"-24" gas guns @ 10.5lbs or more compared to a bolt in 7.62/.308.

I don't think it takes the integral f(x) by separation of parts to figure out that the bullet from a 7.62/.308 round has left the barrel before majiks has imparted their say-so in the matter.

Yes, barrel whip, harmonics yada yada are real... buy good shit from good people to minimize the effect.

Those that shoot below 20" pipe and add cans go into another universe that is parallel, real and frightening... because it is REAL.

20" pipe and +10.5lb rifle less scope, scope mount, ammo, etc... bend over, I'm driving: hot, straight and normal.

 

[LoneWolfUSMC]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DavidAR10</div><div class="ubbcode-body">I've never experienced different "riding techniques" in 20"-24" gas guns @ 10.5lbs or more compared to a bolt in 7.62/.308.

I don't think it takes the integral f(x) by separation of parts to figure out that the bullet from a 7.62/.308 round has left the barrel before majiks has imparted their say-so in the matter.

Yes, barrel whip, harmonics yada yada are real... buy good shit from good people to minimize the effect.

Those that shoot below 20" pipe and add cans go into another universe that is parallel, real and frightening... because it is REAL.

20" pipe and +10.5lb rifle less scope, scope mount, ammo, etc... bend over, I'm driving: hot, straight and normal. </div></div>

Could you possibly translate and re-post that in English?

 

[JPShooter]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body">Could you possibly translate and re-post that in English? </div></div>

+1

 

[Heronion]

Re: Gas Gun Techniques???

Sounds like if my shit is good enough I don't have to worry about physics.

 

[B4forever]

Re: Gas Gun Techniques???

The fundementals are obviously the same, but it my experience most shooters shoot a bolt gun better. My personal opinion is that alot of it has to do with mindset. When your behind a bolt gun you know that you have to make that one shot count. Even though we were issued M110's I always made our new shooters start out on the M24.

 

[Randoman5]

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: DavidAR10</div><div class="ubbcode-body">I've never experienced different "riding techniques" in 20"-24" gas guns @ 10.5lbs or more compared to a bolt in 7.62/.308.

I don't think it takes the integral f(x) by separation of parts to figure out that the bullet from a 7.62/.308 round has left the barrel before majiks has imparted their say-so in the matter.

Yes, barrel whip, harmonics yada yada are real... buy good shit from good people to minimize the effect.

Those that shoot below 20" pipe and add cans go into another universe that is parallel, real and frightening... because it is REAL.

20" pipe and +10.5lb rifle less scope, scope mount, ammo, etc... bend over, I'm driving: hot, straight and normal. </div></div>

Could you possibly translate and re-post that in English? </div></div>

Based on high speed video I've seen it seems like the round usually exits the barrel before the action starts working. Obviously after the round has left the barrel nothing the gun does can have any effect on it's flight. It makes one wonder how much difference there really is between a rifle that's semi-automatic and one that is not with all other factors being equal.

I definitely have a lot less experience than a lot of the members on this board but in the few thousand rounds I have fired it seems like if I can hold the rifle still through the pull of the trigger the rest takes care of itself.

 

[epaultmbt]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DavidAR10</div><div class="ubbcode-body">I've never experienced different "riding techniques" in 20"-24" gas guns @ 10.5lbs or more compared to a bolt in 7.62/.308.

I don't think it takes the integral f(x) by separation of parts to figure out that the bullet from a 7.62/.308 round has left the barrel before majiks has imparted their say-so in the matter.

Yes, barrel whip, harmonics yada yada are real... buy good shit from good people to minimize the effect.

Those that shoot below 20" pipe and add cans go into another universe that is parallel, real and frightening... because it is REAL.

20" pipe and +10.5lb rifle less scope, scope mount, ammo, etc... bend over, I'm driving: hot, straight and normal. </div></div>


This is awesome.

 

[elfster1234]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Randoman5</div><div class="ubbcode-body">Based on high speed video I've seen it seems like the round usually exits the barrel before the action starts working. Obviously after the round has left the barrel nothing the gun does can have any effect on it's flight. It makes one wonder how much difference there really is between a rifle that's semi-automatic and one that is not with all other factors being equal. </div></div>

I don't think the above comment is true as brass in a semi-auto is being ejected under pressure and the bolt is moving the second gas hits the gas tube... yes, it is down to crazy milliseconds between the bullet coming out of the barrel and the bolt starting to cycle, but I think the above comment is wrong.... you show me the crazy slow motion video of this and i'll eat my words. If the above comment was the case and true, then semi-autos would be on the same tack driving level as bolt actions making them obsolete. Even semi-auto brass will buldge more at the base in comparison to bolt action due to the very reason of it being ejected under pressure.

Bolt action = no gas tube, no piston, no brass being ejected under pressure.... Having a bolt action with a <span style="text-decoration: underline"><span style="font-weight: bold">closed breech</span></span> through the entire shot from pull of trigger to bullet flight with consistant pressure behind the bullet and non-moving internal parts is being under-estimated in the above statement IMO.

 

[DavidAR10]

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: DavidAR10</div><div class="ubbcode-body">I've never experienced different "riding techniques" in 20"-24" gas guns @ 10.5lbs or more compared to a bolt in 7.62/.308.

I don't think it takes the integral f(x) by separation of parts to figure out that the bullet from a 7.62/.308 round has left the barrel before majiks has imparted their say-so in the matter.

Yes, barrel whip, harmonics yada yada are real... buy good shit from good people to minimize the effect.

Those that shoot below 20" pipe and add cans go into another universe that is parallel, real and frightening... because it is REAL.

20" pipe and +10.5lb rifle less scope, scope mount, ammo, etc... bend over, I'm driving: hot, straight and normal. </div></div>

Could you possibly translate and re-post that in English? </div></div>

Read slower, Kopfjäger.

I'm an old man and won't get off the porch for pissing contests.

'76-'86 World Tour, and don't remember you being around.

Was teaching at Stone Bay in '85-'86, with Cpl. Conrad, Cpl. Knowles, Sgt. Perry
and a few others. And don't remember you being around.

BTW, Cpl. Grady Graves of Tennessee did the artwork. We all did the best
we could do with looking up the correct spelling of Kopfjäger and ran with it
from multiple USMC documents.

 

[Randoman5]

Re: Gas Gun Techniques???

<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: Randoman5</div><div class="ubbcode-body">Based on high speed video I've seen it seems like the round usually exits the barrel before the action starts working. Obviously after the round has left the barrel nothing the gun does can have any effect on it's flight. It makes one wonder how much difference there really is between a rifle that's semi-automatic and one that is not with all other factors being equal. </div></div>

I don't think the above comment is true as brass in a semi-auto is being ejected under pressure and the bolt is moving the second gas hits the gas tube... yes, it is down to crazy milliseconds between the bullet coming out of the barrel and the bolt starting to cycle, but I think the above comment is wrong.... you show me the crazy slow motion video of this and i'll eat my words. If the above comment was the case and true, then semi-autos would be on the same tack driving level as bolt actions making them obsolete. Even semi-auto brass will buldge more at the base in comparison to bolt action due to the very reason of it being ejected under pressure.

Bolt action = no gas tube, no piston, no brass being ejected under pressure.... Having a bolt action with a <span style="text-decoration: underline"><span style="font-weight: bold">closed breech</span></span> through the entire shot from pull of trigger to bullet flight with consistant pressure behind the bullet and non-moving internal parts is being under-estimated in the above statement IMO. </div></div>

I stand corrected.

Check out this guy's channel. He has some amazing videos, including this one.

http://youtu.be/q5EeOvxI1jQ

 

[DavidAR10]

Re: Gas Gun Techniques???

I think that my '98 Dodge tailgate and MTM gun cleaning cradle was more stable.

Nice & expensive equipment, though.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Randoman5</div><div class="ubbcode-body"><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: Randoman5</div><div class="ubbcode-body">Based on high speed video I've seen it seems like the round usually exits the barrel before the action starts working. Obviously after the round has left the barrel nothing the gun does can have any effect on it's flight. It makes one wonder how much difference there really is between a rifle that's semi-automatic and one that is not with all other factors being equal. </div></div>

I don't think the above comment is true as brass in a semi-auto is being ejected under pressure and the bolt is moving the second gas hits the gas tube... yes, it is down to crazy milliseconds between the bullet coming out of the barrel and the bolt starting to cycle, but I think the above comment is wrong.... you show me the crazy slow motion video of this and i'll eat my words. If the above comment was the case and true, then semi-autos would be on the same tack driving level as bolt actions making them obsolete. Even semi-auto brass will buldge more at the base in comparison to bolt action due to the very reason of it being ejected under pressure.

Bolt action = no gas tube, no piston, no brass being ejected under pressure.... Having a bolt action with a <span style="text-decoration: underline"><span style="font-weight: bold">closed breech</span></span> through the entire shot from pull of trigger to bullet flight with consistant pressure behind the bullet and non-moving internal parts is being under-estimated in the above statement IMO. </div></div>

I stand corrected.

Check out this guy's channel. He has some amazing videos, including this one.

http://youtu.be/q5EeOvxI1jQ </div></div>

 

[Lowlight]

Re: Gas Gun Techniques???

The bolt absolutely begins moving before the bullet leaves the barrel,and even in that 556 infrared video you can see why. The problem is trying to watch both ends at the same time.

The bolt moves before it unlocks, and that movement has impact on the system. Also an Ar10 shooting a 308 is not a 556. Heavier component moving the system more not too mention a slower bullet. The gas moves 5x faster than the bullet and the barrel after the gas block is not 4x shorter than the distance to the bolt. Hence you can absolutely influence the accuracy. There are many more milliseconds to a gas gun compared to anything else.

David,

I was in the Oct 86 class at Stones Bay I don't recall a single thing in the USMC program that would have made you an expert in the operation of an AR10? The t shirt was a nice touch to prove your point, i have mine here too, that and $4.06 I can get my no whip mocca in the morning. . The USMC program was pretty weak when it comes to operating a 308 gas gun back then and a 556 is not the same, not nearly the weight or recoil.

 

[DavidAR10]

Re: Gas Gun Techniques???

I apologize to all but directly to

LoneWolfUSMC.

I've hit the Merlot at 25oz tonight, {two 5oz.glasses per Doc's orders for the ticker} and it makes me mean.

Sorry to all for being an ass.

Hitting the rack. nite nite

EDIT: saw Lowlight's post while it took me 5 min. to apologize. Last class I taught was APR86.

Lowlight, I'll be back... and mellow.

 

[Randoman5]

Re: Gas Gun Techniques???

I was never a marine or a sniper, but I think this is a really interesting topic.

Not to get off topic but,

Lone Wolf,

I was kind of disappointed in the results you got from the AAC-SD and I realized that I could buy a rifle from DPMS for about what the Remington, DBM and a different stock would cost me that according to everything I read would outshoot the Remington and have better ergonomics and cheaper magazines to boot.

I was curious if you ever got it to shoot any better.

 

[hk dave]

Re: Gas Gun Techniques???

This thread has left me feeling all fuzzy and warm.

Watching that vid, it looks to me like there is movement and lots of heat and pressure before anything leaves the bore.

I frankly believe frank.

 

[Randoman5]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hk dave</div><div class="ubbcode-body">This thread has left me feeling all fuzzy and warm.

Watching that vid, it looks to me like there is movement and lots of heat and pressure before anything leaves the bore.

I frankly believe frank. </div></div>

Yeah, for sure. That's why I stood corrected.

I paused it and watched closely a bunch of times. The gas definitely reaches the bolt before the round leaves the barrel and it looks like it may have started to move too. Most of the high speed I'd seen before was pistols and SMGs which have shorter barrels and are recoil or blowback operated rather than gas. I had no idea the gas would move so much more quickly than the bullet.

 

[Lowlight]

Re: Gas Gun Techniques???

That rifle in the video is a 556, now reduce the bullet speed by 400fps and consider with a Mk 11 you have 7" of a 20" barrel after the gas block. With the gas moving 5x faster than the bullet you have 7" left while the gas only has to move 13" in the same amount of time.

The delay comes from the distance the bolt carrier moves before unlocking the bolt from the lugs. As noted above, often the casings are blown out because they extract under pressure.

Driving a gasser requires a lot more trigger control and follow through.

 

[elfster1234]

Re: Gas Gun Techniques???

you are totally right lowlight... it is MUCH MORE pronounce in .308 and above cartridges in comparison to 556 and smaller bullets.... especially when a AR10 type AR's bolt carrier is damn near twice the size and weight of the ar15 type AR.... big time difference IMO when i shoot my LMT MWS .308 and shooting my RRA .223 rifle. Like said before and I know it sounds crazy, but you kinda "drive" a gasser... It really is all about keeping a consistant technique, positioning, and cheek weld. I think there is a reason to why there is hardly any cartridges .308 and above on this list top ten: http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=3523625


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">The bolt absolutely begins moving before the bullet leaves the barrel,and even in that 556 infrared video you can see why. The problem is trying to watch both ends at the same time.

The bolt moves before it unlocks, and that movement has impact on the system. Also an Ar10 shooting a 308 is not a 556. Heavier component moving the system more not too mention a slower bullet. The gas moves 5x faster than the bullet and the barrel after the gas block is not 4x shorter than the distance to the bolt. Hence you can absolutely influence the accuracy. There are many more milliseconds to a gas gun compared to anything else.

David,

I was in the Oct 86 class at Stones Bay I don't recall a single thing in the USMC program that would have made you an expert in the operation of an AR10? The t shirt was a nice touch to prove your point, i have mine here too, that and $4.06 I can get my no whip mocca in the morning. . The USMC program was pretty weak when it comes to operating a 308 gas gun back then and a 556 is not the same, not nearly the weight or recoil. </div></div>

 

[Mo_Zam_Beek]

Re: Gas Gun Techniques???

Question - is it just me?

I have noticed a significant difference in the trigger between between a bolt gun and a gas gun in three distinct areas

- pull weight
- lock time
- the gasser trigger has a much smaller sweet spot for a 'true' straight press back

When slung up and dry firing at an object in the distance roughly the size of my stadia width, achieving a straight trigger press with a bolt gun (unadjusted AW / GAP tuned 3.5# standard Rem) vs M14 match / SR25 the bolt trigger is better in every respect. I notice that if the gas gun is not 'true' there will be the slightest wiggle of the reticle at the point where I call the shot. By comparison it is hard to get sloppy enough with the bolt gun trigger so as to induce reticle wiggle.


Good luck

 

[pshell]

Re: Gas Gun Techniques???

Agreed with the 3 recoil impulses and better driving technique.

Something else to take into consideration is the ergonomics of the gun. The AR platform makes you run the rifle higher off the ground and the pistol grip is easy to "monkey grip" without too much thought. If your trained to shoot an M4, it's harder to shoot something like an M110 well. Your forcing the rifle all over the place, anticipating the follow up shot before your done. I really have to concentrate to shoot an AR platform at distance. The .223 are much more forgiving for some reason. I would imagine faster bullet speed and less anticipated recoil. I work on those weapon systems to this day, although I've been shooting them for over five years. You can perform great or look like a fool very quickly with a .308 gasser.
I think the bottom line is bolt guns are much more forgiving comparatively.

 

[pshell]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mo_Zam_Beek</div><div class="ubbcode-body">Question - is it just me?

I have noticed a significant difference in the trigger between between a bolt gun and a gas gun in three distinct areas

- pull weight
- lock time
- the gasser trigger has a much smaller sweet spot for a 'true' straight press back

When slung up and dry firing at an object in the distance roughly the size of my stadia width, achieving a straight trigger press with a bolt gun (unadjusted AW / GAP tuned 3.5# standard Rem) vs M14 match / SR25 the bolt trigger is better in every respect. I notice that if the gas gun is not 'true' there will be the slightest wiggle of the reticle at the point where I call the shot. By comparison it is hard to get sloppy enough with the bolt gun trigger so as to induce reticle wiggle.


Good luck </div></div>

Yes, the 2 stage in most gassers blows. I like to run a wilson combat single stage in my LR AR's and it's a world apart from a KAC 110 trigger. I would buy one for double to price. In my mind, 2-stage triggers are junk.
I love my 1911's for the trigger and I love my 700 for it's trigger. Both move and fire almost at the same time. I want to command detonate when my finger moves, not after I take up a 1/4'' of travel, then break the ramp. If the trigger moves, it should fire.
(disclaimer) If your worried about AD's, GET YOUR FINGER OFF THE TRIGGER! 2-stages are built for lawyers, not shooters.

 

[Tahoe333]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pshell</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mo_Zam_Beek</div><div class="ubbcode-body">Question - is it just me?

I have noticed a significant difference in the trigger between between a bolt gun and a gas gun in three distinct areas

- pull weight
- lock time
- the gasser trigger has a much smaller sweet spot for a 'true' straight press back

When slung up and dry firing at an object in the distance roughly the size of my stadia width, achieving a straight trigger press with a bolt gun (unadjusted AW / GAP tuned 3.5# standard Rem) vs M14 match / SR25 the bolt trigger is better in every respect. I notice that if the gas gun is not 'true' there will be the slightest wiggle of the reticle at the point where I call the shot. By comparison it is hard to get sloppy enough with the bolt gun trigger so as to induce reticle wiggle.


Good luck </div></div>

Yes, the 2 stage in most gassers blows. I like to run a wilson combat single stage in my LR AR's and it's a world apart from a KAC 110 trigger. I would buy one for double to price. In my mind, 2-stage triggers are junk.
I love my 1911's for the trigger and I love my 700 for it's trigger. Both move and fire almost at the same time. I want to command detonate when my finger moves, not after I take up a 1/4'' of travel, then break the ramp. If the trigger moves, it should fire.
(disclaimer) If your worried about AD's, GET YOUR FINGER OFF THE TRIGGER! 2-stages are built for lawyers, not shooters. </div></div>

SD3G = nuff said!

 

[MistWolf]

Re: Gas Gun Techniques???

There are a couple of problems with the infra red video. It's frame rate is too slow to capture all of the events during firing sequence. Second, it's tracking how fast the <span style="font-style: italic">heat</span> travels, not how fast the bullet & gas travel. Notice that the entire length of the barrel heats equally. Also notice the heat first seen at the action is coming from the chamber, not the gases traveling down the gas tube.

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.

Once the barrel uncorks the barrel, the gases exit at roughly 5,700 fps. However, when they pass through the gas port, because of Bernoulli's Principle, velocity drops to less than supersonic. The gases lose speed while passing through the gas port.

If the action of the AR began opening while the bullet was still in the barrel, "dwell time" wouldn't change BCG velocity. Adding a suppressor would not increase the velocity of the BCG. That's because the bullet would be in the same place in the barrel regardless of dwell time. The gas key would still disconnect from the gas tube at the same time and therefore, the same amount of gas would be operating the system. The reason a suppressor increases BCG speed is that it increases blow down time which forces gases through the gas port at higher pressure which means it fills the gas system with more gas at a faster rate.

A bolt action rifle exhibits an advantage in accuracy because the barrel harmonics are not interrupted by a gas block, gas port and tube and the chamber of a bolt action rifle can be held to a tighter specification while maintaining reliable extraction

 

[elfster1234]

Re: Gas Gun Techniques???

are you saying that brass is not under some type of preasure while being ejected then?



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MistWolf</div><div class="ubbcode-body">There are a couple of problems with the infra red video. It's frame rate is too slow to capture all of the events during firing sequence. Second, it's tracking how fast the <span style="font-style: italic">heat</span> travels, not how fast the bullet & gas travel. Notice that the entire length of the barrel heats equally. Also notice the heat first seen at the action is coming from the chamber, not the gases traveling down the gas tube.

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.

Once the barrel uncorks the barrel, the gases exit at roughly 5,700 fps. However, when they pass through the gas port, because of Bernoulli's Principle, velocity drops to less than supersonic. The gases lose speed while passing through the gas port.

If the action of the AR began opening while the bullet was still in the barrel, "dwell time" wouldn't change BCG velocity. Adding a suppressor would not increase the velocity of the BCG. That's because the bullet would be in the same place in the barrel regardless of dwell time. The gas key would still disconnect from the gas tube at the same time and therefore, the same amount of gas would be operating the system. The reason a suppressor increases BCG speed is that it increases blow down time which forces gases through the gas port at higher pressure which means it fills the gas system with more gas at a faster rate.

A bolt action rifle exhibits an advantage in accuracy because the barrel harmonics are not interrupted by a gas block, gas port and tube and the chamber of a bolt action rifle can be held to a tighter specification while maintaining reliable extraction </div></div>

 

[Big Dog Steel]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pshell</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mo_Zam_Beek</div><div class="ubbcode-body">Question - is it just me?

I have noticed a significant difference in the trigger between between a bolt gun and a gas gun in three distinct areas

- pull weight
- lock time
- the gasser trigger has a much smaller sweet spot for a 'true' straight press back

When slung up and dry firing at an object in the distance roughly the size of my stadia width, achieving a straight trigger press with a bolt gun (unadjusted AW / GAP tuned 3.5# standard Rem) vs M14 match / SR25 the bolt trigger is better in every respect. I notice that if the gas gun is not 'true' there will be the slightest wiggle of the reticle at the point where I call the shot. By comparison it is hard to get sloppy enough with the bolt gun trigger so as to induce reticle wiggle.


Good luck </div></div>

Yes, the 2 stage in most gassers blows. I like to run a wilson combat single stage in my LR AR's and it's a world apart from a KAC 110 trigger. I would buy one for double to price. In my mind, 2-stage triggers are junk.
I love my 1911's for the trigger and I love my 700 for it's trigger. Both move and fire almost at the same time. I want to command detonate when my finger moves, not after I take up a 1/4'' of travel, then break the ramp. If the trigger moves, it should fire.
(disclaimer) If your worried about AD's, GET YOUR FINGER OFF THE TRIGGER! 2-stages are built for lawyers, not shooters. </div></div>

I guess someone should have told AI that. When i shoot a gas gun I typically hold the trigger to the rear until after the recoil cycle then let it click forward for the next shot.

 

[MistWolf]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: elfster1234</div><div class="ubbcode-body">are you saying that brass is not under some type of preasure while being ejected then?</div></div>

Pressure in the rifle does not instantly drop to atmospheric when the bullet uncorks the barrel. It takes time, so there will still be some residual pressure when the case is extracted. I don't know how much exactly, but the residual pressure when the case is extracted is likely to be less than 100 psi. Pressure inside the barrel will reach 55,000 psi or more and can cause lethal damage to the shooter. 100 psi is enough to penetrate skin and put air bubbles in the blood, or destroy an eye or an ear drum. Extraction under high pressures is unsafe and will be difficult because the brass will still be stuck to the chamber walls. Designers ensure extraction won't happen until pressures drop to safe levels

 

[pshell]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
Yes, the 2 stage in most gassers blows. I like to run a wilson combat single stage in my LR AR's and it's a world apart from a KAC 110 trigger. I would buy one for double to price. In my mind, 2-stage triggers are junk.
I love my 1911's for the trigger and I love my 700 for it's trigger. Both move and fire almost at the same time. I want to command detonate when my finger moves, not after I take up a 1/4'' of travel, then break the ramp. If the trigger moves, it should fire.
(disclaimer) If your worried about AD's, GET YOUR FINGER OFF THE TRIGGER! 2-stages are built for lawyers, not shooters. </div></div>
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
I guess someone should have told AI that. When i shoot a gas gun I typically hold the trigger to the rear until after the recoil cycle then let it click forward for the next shot. </div></div>

Thanks for the input, now I know how to reset my trigger.

 

[Lowlight]

Re: Gas Gun Techniques???

Pressure is bled off... you have 55,000psi at the chamber at the time of ignition, you you also increase the volume by moving the bullet down the barrel and it bleeds off pressure by allowing gas to pass the bullet via the grooves. You've increased the space that can hold the 55k psi by opening up the distance.

Also since when does moving a volume of gas from a big hole to small hole decrease pressure ?

you never carry all the chamber pressure to the gas port, but you carry a lot.

Also I have seen a semi auto explode, it bends the metal, breaks the parts, luckily most takes the path of least resistance and blows down the magazine well, but I have also seen in the same explosion the BCG fly back into a Magpul PRS Stock buried inside so the bolt was not sticking out. That is pressure.... Blown bolt actions also peel back the barrel, beyond the chamber. The pressure carries to some degree, just not all.

The BCG begins to unlock... the gas is too fast and takes the path of least resistance, the millisecond the bullet reaches the port the gas is racing down it 5x faster than the bullet is exiting the rest of the barrel. The bullet can't win and the bled off from the opened up volume and from lost gas slows it down to operate correctly.

 

[Graham]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pshell</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I guess someone should have told AI that. When i shoot a gas gun I typically hold the trigger to the rear until after the recoil cycle then let it click forward for the next shot.</div></div>Thanks for the input, now I know how to reset my trigger.</div></div>How does that differ from proper trigger follow-through on a bolt gun?<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">...that and $4.06 I can get my no whip mocca in the morning.</div></div>Where can you get a Mocha for $ 4.06? Is that a large with a double-shot? Here I'm at $4.80 on a simple no-foam Latte, so I guess the 80's were not kind to me either.

 

[Lowlight]

Re: Gas Gun Techniques???

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

]Where can you get a Mocha for $ 4.06? Is that a large with a double-shot? Here I'm at $4.80 on a simple no-foam Latte, so I guess the 80's were not kind to me, either.

</div></div>

It's all about personality, they love me at Starbucks, and at times I have even scored my $4 drink for $3, cause I am sassy that way. I chat the girls up, give advice on how to land a guy as awesome as me, stuff that really resonates with the Starbucks crowd.

I may consider lessons on the technique but you need that certain Joie de vivre for it to work.

 

[Graham]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">I chat the girls up, give advice on how to land a guy as awesome as me, stuff that really resonates with the Starbucks crowd. I may consider lessons on the technique but you need that certain Joie de vivre for it to work.</div></div>My lack of charisma explains it then: I tell them that I really don't care what kind of a day I am going to have; just please make my damn coffee.

I likely have no future as an instructor for Horus.

 

[LoneWolfUSMC]

Re: Gas Gun Techniques???

You mean Starbucks charges you guys? I always wondered why they had cash registers there.

My take on the semi-auto debate has little to do with mechanics and much to do with the shooter. We can mind-fuck ourselves into doing amazing things and then our Type-A personality steps in and blames it on the weapon.

The only credible argument I have heard is lock time. The hammer swing on a AR takes a hell of a lot longer than the striker on a modern bolt. It causes the mass to change directions. We are all slaves to physics. How much impact it has on the alignment of the sights is going to depend on the shooters ability to hold a solid position through the firing process.

I have discussed the gas system at length with engineers, barrel makes, and people with lots of letters behind their names. It's not just a matter of where the gas is going or how long it takes. It's a matter of building pressure and overcoming mass. I still don't have enough actual data to make an assertive statement, but most of the folks I have spoke with are convinced that on a rifle length gas system the bolt is still solidly locked when the bullet leaves the muzzle.

 

[LoneWolfUSMC]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DavidAR10</div><div class="ubbcode-body">I apologize to all but directly to
LoneWolfUSMC.</div></div>

I appreciate the apology. I was truly attempting to digest what you posted.

However know that I have long ago stopped praying at the alter of the Scout Sniper Basic Course. My re-education began when I started asking myself "why" instead of "how" and I sought the math behind the means.

There are piles of "Sniper Instructors" out there that repeat the same shit that was printed in the manual decades ago, but have no idea why it was there, how it got there or why it just doesn't work sometimes. I have to deal with it in LE Schools when they want to do something because the SEALs do it that way.

 

[MistWolf]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Pressure is bled off... you have 55,000psi at the chamber at the time of ignition, you you also increase the volume by moving the bullet down the barrel and it bleeds off pressure by allowing gas to pass the bullet via the grooves. You've increased the space that can hold the 55k psi by opening up the distance.</div></div>

Pressure <span style="font-style: italic">builds</span> to 55k psi (or whatever max pressure ends up being, it does not instantly become 55k. Yes, as the bullet travels, pressure drops because of the increase in volume

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Also since when does moving a volume of gas from a big hole to small hole decrease pressure ?</div></div>

Go back and read again what I wrote. A simple port does not reduce pressure, it restricts flow. Since it acts as a venturi, the <span style="font-style: italic">velocity</span> of the gas drops to less than supersonic

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Also I have seen a semi auto explode, it bends the metal, breaks the parts, luckily most takes the path of least resistance and blows down the magazine well, but I have also seen in the same explosion the BCG fly back into a Magpul PRS Stock buried inside so the bolt was not sticking out. That is pressure.... Blown bolt actions also peel back the barrel, beyond the chamber. The pressure carries to some degree, just not all.</div></div>

Yes, there is quite a bit of pressure. We all know that. Rifles let go because the pressure spikes too quick and/or to a higher level than the action and/or barrel can contain, either due to a restriction in the bore or ammo developing too much pressure and/or too quickly

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The BCG begins to unlock... the gas is too fast and takes the path of least resistance, the millisecond the bullet reaches the port the gas is racing down it 5x faster than the bullet is exiting the rest of the barrel. The bullet can't win and the bled off from the opened up volume and from lost gas slows it down to operate correctly. </div></div>

The constant velocity of the gas from burning smokeless powder is roughly 5,700 fps (I don't have my reloading manual with me and I'm going by memory). This is why is very difficult to load small arms to velocities exceeding 4,000 fps. While 5,700 fps is 5x faster than most pistol velocities, it's not 5x faster than 5.56 velocities.

The muzzle velocity of a 7.62x51 is roughly 2,750 fps. It's piston is located right at the gas port. Studies by the Army show that the bullet is several feet (I think it's 15) from the muzzle before the gas piston begins moving. The bullet of a 5.56 is traveling at least that fast and the distance and volume of the gas tube leading to the piston of the AR is greater.

If there were such terrific pressures making their way into the expansion chamber, if the bolt were to unlock while the bullet is still in the bore which is somewhere between 10 a 20 thousand at the gas port, you would get much more than a soft puff of air when the gases did occasionally hit your face

 

[finbox]

Re: Gas Gun Techniques???

On my DPMS 6.5 CM the bolt is moving before the bullet is leavening the barrel.

How to test:
Shoot 3 5 round groups WITH A LOADED 20 ROUND MAG ( the bolt opens and closes)

Right after this load one round in a mag at a time and let the bolt hold open work. ( bolt movement has changed, it does not move forward )

shoot 3 5 round groups like this....then look at your results.

Bolt movement is affecting your groups.

I realize that the bolt carrier is moving a lot slower than the bullet, but if the bullet has left the barrel then the above test would be identical.

Ever had the last round in a mag be a flyer? The above is why.

 

[MistWolf]

Re: Gas Gun Techniques???

A change in POI due to a change in harmonics, yes. Due to the bolt closing? No. That would only happen if the bolt were closing while the bullet was still in the barrel. That means several thousand psi of gas would be venting from the chamber with each shot, the same pressure that's exiting the muzzle and it would be just as deadly

 

[finbox]

Re: Gas Gun Techniques???

I agree with you 100%

You would think harmonics should be the same too.

But give it a try.

 

[Lowlight]

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: Lowlight</div><div class="ubbcode-body">Pressure is bled off... you have 55,000psi at the chamber at the time of ignition, you you also increase the volume by moving the bullet down the barrel and it bleeds off pressure by allowing gas to pass the bullet via the grooves. You've increased the space that can hold the 55k psi by opening up the distance.</div></div>

Pressure <span style="font-style: italic">builds</span> to 55k psi (or whatever max pressure ends up being, it does not instantly become 55k. Yes, as the bullet travels, pressure drops because of the increase in volume

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Also since when does moving a volume of gas from a big hole to small hole decrease pressure ?</div></div>

Go back and read again what I wrote. A simple port does not reduce pressure, it restricts flow. Since it acts as a venturi, the <span style="font-style: italic">velocity</span> of the gas drops to less than supersonic

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Also I have seen a semi auto explode, it bends the metal, breaks the parts, luckily most takes the path of least resistance and blows down the magazine well, but I have also seen in the same explosion the BCG fly back into a Magpul PRS Stock buried inside so the bolt was not sticking out. That is pressure.... Blown bolt actions also peel back the barrel, beyond the chamber. The pressure carries to some degree, just not all.</div></div>

Yes, there is quite a bit of pressure. We all know that. Rifles let go because the pressure spikes too quick and/or to a higher level than the action and/or barrel can contain, either due to a restriction in the bore or ammo developing too much pressure and/or too quickly

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The BCG begins to unlock... the gas is too fast and takes the path of least resistance, the millisecond the bullet reaches the port the gas is racing down it 5x faster than the bullet is exiting the rest of the barrel. The bullet can't win and the bled off from the opened up volume and from lost gas slows it down to operate correctly. </div></div>

The constant velocity of the gas from burning smokeless powder is roughly 5,700 fps (I don't have my reloading manual with me and I'm going by memory). This is why is very difficult to load small arms to velocities exceeding 4,000 fps. While 5,700 fps is 5x faster than most pistol velocities, it's not 5x faster than 5.56 velocities.

The muzzle velocity of a 7.62x51 is roughly 2,750 fps. It's piston is located right at the gas port. Studies by the Army show that the bullet is several feet (I think it's 15) from the muzzle before the gas piston begins moving. The bullet of a 5.56 is traveling at least that fast and the distance and volume of the gas tube leading to the piston of the AR is greater.

If there were such terrific pressures making their way into the expansion chamber, if the bolt were to unlock while the bullet is still in the bore which is somewhere between 10 a 20 thousand at the gas port, you would get much more than a soft puff of air when the gases did occasionally hit your face</div></div>

Dude you are smoking crack... the bullet is several feet LOL

And there is more than a "little puff of smoke" all you have to do is add a suppressor to see it overwhelms and it is not even pointed at your face, it is blocked in all manners of ways and still hits your face because it is overwhelming. It snakes around the BCG and the charging handle to exit and hit you in the face, why people use a gas blocker. So coming from the "tiny" gas port it is still enough to scar your Oakley's without much effort. I even have video of unburnt powder igniting on exit with the casing.

Shoot 3 rounds and look at your magazine with a 308, which in a gasser is lucky to go 2600fps not 2750fps, which errors like that are great examples of mis-information, just enough to sound right, but yet so wrong. The bullets in a 308, say Mk 11 are covered in black, inside the magazine, down to the bottom.

Guessing doesn't replace real world experience on the subject and seeing is believing... the bullet is not gone. Sorry, you're wrong as wrong can be, especially with your last 15 ft statement... LOL

 

[Captain Kirk]

Re: Gas Gun Techniques???

 

[Lowlight]

Re: Gas Gun Techniques???

Here is my Point, High Speed video I took a still of, and this is a handgun...

The amount of bleed off is huge, in front of the bullet, but also look at the slide it is moving.

This is nowhere near the distance of a rifle, and yet, the slide is opening when the bullet is in the bore.

Here is the gas bleed off in front of the bullet and especially look at the grid on the slide, at a rest those marks line up.

If the bullet loses in a 5" barrel, I promise it is losing in a rifle. Part of the gas that goes in front of the bullet will begin to pre-load the gas tube, so it's not that hard to reach the pressure necessary.

I think I may have to take the dive and rent a Phantom to prove it,

 

[taliv]

Re: Gas Gun Techniques???

so frank, you're saying if the bullet is doing 2600 fps, the gas is going 5x = 13,000 fps?



the bullet is a long way from the barrel before the bolt UNLOCKS.

of course, the bolt starts "moving" backward from recoil the same time the bullet starts moving forward.


mistwolf is right.

 

[Captain Kirk]

Re: Gas Gun Techniques???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: taliv</div><div class="ubbcode-body"> of course, the bolt starts "moving" backward from recoil the same time the bullet starts moving forward.</div></div>

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.

 

[Lowlight]

Re: Gas Gun Techniques???

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.

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.