scooterdog Posted November 15, 2014 Share Posted November 15, 2014 Lots of good info on this thread. Got to try one of these. Link to comment Share on other sites More sharing options...
Vespid_Wasp Posted January 5, 2015 Share Posted January 5, 2015 The gas that is bled off into the gas tube only does one thing.....unlock the bolt. Once the bolt is unlocked.....you are then relying on the pressure in the barrel to push the bolt back. Essentially.....when you retard the amount of gas going into the bolt carrier (whether at the gas block or gas key).....you are determining the amount of pressure that is available to 'blow' the bolt back. By retarding the bleed off gas.....you are allowing the bullet to travel farther down the barrel before the bolt unlocks. The farther down the barrel the bullet goes.....means that there is less pressure available to blow the bolt back. I was under the impression that the gas entering the bolt carrier and expanding between the rings of the bolt and the expansion chamber in the carrier provided the entirety of the force that actuates the bolt carrier. Pushing forward on the bolt as it unlocks to mitigate force on the bolt lugs while simultaneously moving the carrier back until the cam pin rotates the bolt. I always thought that pulse of gas provided all the impulse to move the carrier to the rear until it is vented out the right side of the carrier, and then the inertia possessed by the rearward moving carrier completed the cycle. I thought that the time of movement allowed by the travel of the carrier before the cam pin track unlocks the bolt allowed the pressure in the barrel to drop to a negligible amount, excepting carbine length guns where the bolt may unlock under pressure. Either way, I'm keen to try one of these new adjustable keys. Especially on a carbine once my new suppressor comes out of jail. Link to comment Share on other sites More sharing options...
Stlhead Posted January 5, 2015 Share Posted January 5, 2015 The gas that is bled off into the gas tube only does one thing.....unlock the bolt. Once the bolt is unlocked.....you are then relying on the pressure in the barrel to push the bolt back. Essentially.....when you retard the amount of gas going into the bolt carrier (whether at the gas block or gas key).....you are determining the amount of pressure that is available to 'blow' the bolt back. By retarding the bleed off gas.....you are allowing the bullet to travel farther down the barrel before the bolt unlocks. The farther down the barrel the bullet goes.....means that there is less pressure available to blow the bolt back. I think there is a flaw in this explanation. The gas unlocks the bolt by causing the bolt carrier to go back, the only way to rotate the bolt and unlock it is by causing the bolt carrier to move to the rear, the pressure in the barrel must already be dropping before the case can be able to be extracted, otherwise the case would not be removed as it would still be stuck to the chamber. The gas that goes through the gas system is responsible for all of the moment of the bolt carrier and as such the bolt. Link to comment Share on other sites More sharing options...
jkrispies Posted January 6, 2015 Share Posted January 6, 2015 Can anybody provide a long term report on this system? I have a 16" carbine system that is over gassed. I was going to get an adjustable block and tossing around the idea of a lightweight carrier in the future. Might kill two birds at once? Link to comment Share on other sites More sharing options...
TRUBL Posted January 6, 2015 Author Share Posted January 6, 2015 The gas that is bled off into the gas tube only does one thing.....unlock the bolt. Once the bolt is unlocked.....you are then relying on the pressure in the barrel to push the bolt back. Essentially.....when you retard the amount of gas going into the bolt carrier (whether at the gas block or gas key).....you are determining the amount of pressure that is available to 'blow' the bolt back. By retarding the bleed off gas.....you are allowing the bullet to travel farther down the barrel before the bolt unlocks. The farther down the barrel the bullet goes.....means that there is less pressure available to blow the bolt back. I think there is a flaw in this explanation. The gas unlocks the bolt by causing the bolt carrier to go back, the only way to rotate the bolt and unlock it is by causing the bolt carrier to move to the rear, the pressure in the barrel must already be dropping before the case can be able to be extracted, otherwise the case would not be removed as it would still be stuck to the chamber. The gas that goes through the gas system is responsible for all of the moment of the bolt carrier and as such the bolt. Actually......it is the gas pressure in the chamber/barrel that pushes the bolt back.....after the bolt carrier has unlocked the bolt. The bolt is NOT pulling the case out of the chamber....its the gas that is acting on the case and the case is pushing the bolt back. The gas that bleeds through the gas tube is pressurizing a piston....which happens to be the bolt, but as the bolt can not move, so the BCG moves back, but that travel is a small amount....note the travel of the cam pin....which unlocks the bolt.....NOW the entire assembly can move back.....and it does, due to the pressure in the barrel. Is there a pressure drop? Well, yes.....and the case is not sticking to the chamber wall. But it is incorrect thinking that the gas in the tube pushing the bolt all the way back to eject the round. Link to comment Share on other sites More sharing options...
StealthyBlagga Posted January 6, 2015 Share Posted January 6, 2015 (edited) As I understand it, the gas from the gas tube flows into the bolt carrier via the carrier key, and pressurizes the chamber between the carrier and the bolt tail. This pressure simultaneously pushes the bolt more firmly forward into battery (in order to keep the bolt closed until chamber pressure falls to safe levels) and pushes the carrier backwards (i.e. towards the buffer). This backwards motion of the carrier serves to impart momentum that ultimately results in the bolt unlocking and the carrier cycling fully. By the time the bolt unlocks, the chamber pressure is supposed to be virtually zero (otherwise some combination of adhesion to the chamber wall and/or case head blow-out would be likely). As I understand it, blowback of the bolt due to residual pressure in the barrel is NOT a meaningful actuating force in the Stoner Direct Gas Impingement system. Caveat: I am a chemist, not an engineer, so I am more than willing to listen to evidence that I have got it wrong. Edited January 6, 2015 by StealthyBlagga Link to comment Share on other sites More sharing options...
Vlad Posted January 6, 2015 Share Posted January 6, 2015 I'm thinking out loud here, but if chamber pressure pushed the bolt and brass back, we would never see rims damaged by the extractor or ripped rims on steel cases. Link to comment Share on other sites More sharing options...
MarkCO Posted January 6, 2015 Share Posted January 6, 2015 Vlad and Stealthy are correct. Allowing excess gas out of the gas block and throttling it at the key is inferior to reducing the gas from the barrel or block. Link to comment Share on other sites More sharing options...
TonytheTiger Posted January 6, 2015 Share Posted January 6, 2015 Go on Mark? I feel like you where just getting warmed up to teach us something. Link to comment Share on other sites More sharing options...
MarkCO Posted January 6, 2015 Share Posted January 6, 2015 I think that is enough. Link to comment Share on other sites More sharing options...
TRUBL Posted January 6, 2015 Author Share Posted January 6, 2015 Based on what you say......piston systems are a huge fail as they will never push the bolt "more firmly into battery" So.....lets take the DI out of this for a bit......and say.....a piston system....they seem to work....but HOW?? The gas goes up in to that little hole and pushes on a piston.....and some companies call it a "short action piston"....why??? because its travel is roughly equal to the travel that the BCG needs to move to unlock the bolt. The piston...ONLY unlocks the bolt....period. Once the bolt is unlocked....the pressure in the barrel, which includes the pressure in the chamber as it is the same pressure.....pushes the shell out of the chamber....which happens to push the bolt and BCG back into the buffer......just like a blow back action.....all you are doing is retarding the time that it happens. By putting an adjustable system in place....you can further retard that time. Now....getting back to gas, or DI systems.......Mark....while being correct that adjustable gas on the block is superior to adjustable gas on the key.....he fails to mention the percentage of loss over time/travel which is like less than 1%.....so his statement, while true, is somewhat benign. And the excess gas? Does not go where you think it goes. I do live is what can be considered EXTREME weather swings......and there has been no difference of effect between either system I run (gas block or gas key). Tim As I understand it, the gas from the gas tube flows into the bolt carrier via the carrier key, and pressurizes the chamber between the carrier and the bolt tail. This pressure simultaneously pushes the bolt more firmly forward into battery (in order to keep the bolt closed until chamber pressure falls to safe levels) and pushes the carrier backwards (i.e. towards the buffer). This backwards motion of the carrier serves to impart momentum that ultimately results in the bolt unlocking and the carrier cycling fully. By the time the bolt unlocks, the chamber pressure is supposed to be virtually zero (otherwise some combination of adhesion to the chamber wall and/or case head blow-out would be likely). As I understand it, blowback of the bolt due to residual pressure in the barrel is NOT a meaningful actuating force in the Stoner Direct Gas Impingement system. Caveat: I am a chemist, not an engineer, so I am more than willing to listen to evidence that I have got it wrong. Link to comment Share on other sites More sharing options...
StealthyBlagga Posted January 6, 2015 Share Posted January 6, 2015 Vlad and Stealthy are correct. Allowing excess gas out of the gas block and throttling it at the key is inferior to reducing the gas from the barrel or block. I assume you mean I am correct in my explanation about the way the Stoner DGI system works - if so, thanks for the confirmation.. As for the relative merits of throttling the gas at the gas block versus at the carrier key, I am not sure I see a significant difference from a theoretical standpoint. At the instant that the gas is being throttled, the bolt carrier/bolt/barrel system is essentially still locked together in both cases. The carrier key only "undocks" from the gas tube when the bolt unlocks, which is after the bullet has left the barrel and the pressure in the gas system has equalized with the atmosphere. There are presumably some minor differences in efficiency (e.g. more gas entering the key may increase leakage at the tube-key interface) and gas dynamics (as a chemist, I know that gas is compressible), so I can believe that there might be a slight difference in timing between the two approaches, but I don't know that this has translated into any difference in handling or reliability that I can detect from behind the trigger. In the end, I think it still comes down to the obvious differences in implementation. An adjustable gas block keeps things simpler at the bolt carrier, and, with the click-adjustable gas block designs now available, likely makes for a more predictable, controllable and stable adjustment. An adjustable carrier key, on the other hand, is easier to retrofit for most folks, and allows the gun to be returned to the original non-adjustable configuration almost instantly (i.e. during a match) in the event that the adjustable system proves problematic (e.g. in adverse conditions etc.) - for the person who wants one rifle to serve both competition and personal protection roles, this could be a significant benefit. I own guns with both systems, and feel 100% comfortable grabbing either for a match. Link to comment Share on other sites More sharing options...
StealthyBlagga Posted January 6, 2015 Share Posted January 6, 2015 Based on what you say......piston systems are a huge fail as they will never push the bolt "more firmly into battery" So.....lets take the DI out of this for a bit......and say.....a piston system....they seem to work....but HOW?? The gas goes up in to that little hole and pushes on a piston.....and some companies call it a "short action piston"....why??? because its travel is roughly equal to the travel that the BCG needs to move to unlock the bolt. The piston...ONLY unlocks the bolt....period. Once the bolt is unlocked....the pressure in the barrel, which includes the pressure in the chamber as it is the same pressure.....pushes the shell out of the chamber....which happens to push the bolt and BCG back into the buffer......just like a blow back action.....all you are doing is retarding the time that it happens. By putting an adjustable system in place....you can further retard that time... Sorry Tim - I am going to stick my neck out and say you are wrong. Indeed, you would be equally wrong about EVERY locked breech design of firearm out there, including other piston-system rifles (AK, FAL etc.) and even pistols (1911 etc.). They all work by imparting inertia on a moving mass (bolt carrier in the case of rifles, slide in the case of pistols) while the breech is still locked. The breech should not ever open while the bullet is still in the barrel - when it does, it usually results in gross case deformation or a kaboom. Now, HOW that inertia is imparted to the moving mass does vary - piston rifles do so with either a short piston (tappet system, like most piston ARs) or long piston (AK), and timing is very important to ensure that the bolt does not unlock prematurely. This is a matter of gas port placement, gas pressure and volume, piston mass, bolt carrier mass, springs and probably a lot of other stuff Mark could bore us with. Indeed, the beauty of the DGI system is that the internal pressure that holds the bolt closed a little longer allows the total reciprocating mass to be reduced significantly, making for a softer-shooting gun and less weight for the soldier to schlep around the battlefield (a key reason Stoner chose this method of operation). However, I do not believe blow back is a factor that contributes to the cycling of any locked breach designs. Some pistols and pistol caliber rifles do use the blow back method of operation, of course, but pistol ammo is far less powerful. As ammo power increases, the reciprocating mass has to increase accordingly, and starts to get unwieldy for rounds much more powerful than .45ACP. Link to comment Share on other sites More sharing options...
MickB Posted January 6, 2015 Share Posted January 6, 2015 Are we forgetting the CETME/HK roller locked action that relies on blow back? No gas piston/tube at all on these designs and fluted chambers to help extraction.... Mick However, I do not believe blow back is a factor that contributes to the cycling of any locked breach designs. Link to comment Share on other sites More sharing options...
TRUBL Posted January 6, 2015 Author Share Posted January 6, 2015 Well.....you can be wrong...it's ok Take the extractor and plunger out of a bolt sometime.....then do some slo-mo video. You'll see I'm right. Tim Link to comment Share on other sites More sharing options...
StealthyBlagga Posted January 6, 2015 Share Posted January 6, 2015 (edited) Are we forgetting the CETME/HK roller locked action that relies on blow back? No gas piston/tube at all on these designs and fluted chambers to help extraction.... Mick However, I do not believe blow back is a factor that contributes to the cycling of any locked breach designs. Smart arse... bugger off back to Australia Even with the delayed roller locking system, the cycle of unlocking starts at the moment of firing. The rollers delay unlocking until the pressure has dropped and the bullet has exited the barrel. The momentum imparted to the mass of the bolt then completes the cycle and extracts the case. The key is that the momentum starts before the pressure has dropped. Edited January 6, 2015 by StealthyBlagga Link to comment Share on other sites More sharing options...
StealthyBlagga Posted January 6, 2015 Share Posted January 6, 2015 Well.....you can be wrong...it's ok Take the extractor and plunger out of a bolt sometime.....then do some slo-mo video. You'll see I'm right. Tim Not sure of your point - if you have such a video, please post it along with an explanation of what it shows and why it supports your assertion. Link to comment Share on other sites More sharing options...
MickB Posted January 6, 2015 Share Posted January 6, 2015 (edited) Let's do some basic math. There will be some assumptions for ease of calculation. 20 inch AR barrel = 0.5 meters (0.508 m for those that want to be exact) M193 55gr projectile muzzle velocity = 3,280 fps = 1,000 metres/sec Projectile spends 0.0005 seconds in the barrel (yes, I am ignoring acceleration, but I am keeping this simple, remember). Now, when the bullet just goes past the gas port, it has about 6 inches (0.15m) of travel left before it exits the muzzle. This means there is 0.00015 seconds until the bullet exits the muzzle and the pressure in the barrel drops back to atmospheric pressure. During that time, the gas has travelled down the gas tube and put pressure on either a piston or bolt carrier to impart kinetic energy to move it rearward. The bolt is still mechanically locked at this point. Now, let's assume a cyclic rate of 1,200 rpm (yes, I know AR cyclic rates are lower but bear with me). That is 20 rounds per second, or 0.05 seconds per round. Where am I going with this? The bullet has left the barrel BEFORE the bolt unlocks, meaning the pressure in the barrel is back to atmospheric and it is the rearward momentum imparted to the piston or bolt carrier (from the gas) that cycles the action. Yes, there is blowback pressure on the case while the projectile is still in the barrel, but that should be gone once the bullet has left the barrel. Mick Edited January 6, 2015 by MickB Link to comment Share on other sites More sharing options...
TRUBL Posted January 6, 2015 Author Share Posted January 6, 2015 Nah.....I'm done, no time to deal with it......I'm confident and in the end....it don't really matter......the bottom line, adjustable gas works, no matter where it is. Link to comment Share on other sites More sharing options...
MickB Posted January 6, 2015 Share Posted January 6, 2015 LOL! you are correct on the roller locked action. The bolt carrier is forced rearward while the bolt rollers are forced to the barrel extension by the high pressure blow back until pressure has dropped in the barrel. Because the carrier is still moving rearward, by the time it has reached the end of its free travel, the rollers have disengaged and the whole assembly continues to move rearward. Timing and burn rate and brass quality are everything on this type of system. Wrong burn rate in some ammunition can screw up the timing and over pressure the system, leading to rims being torn off cases. Mick Are we forgetting the CETME/HK roller locked action that relies on blow back? No gas piston/tube at all on these designs and fluted chambers to help extraction.... Mick However, I do not believe blow back is a factor that contributes to the cycling of any locked breach designs. Smart arse... bugger off back to Australia Even with the delayed roller locking system, the cycle of unlocking starts at the moment of firing. The rollers delay unlocking until the pressure has dropped and the bullet has exited the barrel. The momentum imparted to the mass of the bolt then completes the cycle and extracts the case. The key is that the momentum starts before the pressure has dropped. Link to comment Share on other sites More sharing options...
Vlad Posted January 6, 2015 Share Posted January 6, 2015 Nah.....I'm done, no time to deal with it......I'm confident and in the end....it don't really matter......the bottom line, adjustable gas works, no matter where it is. Err .. how? If you are correct and it barrel pressure that pushes the whole mess backwards, then how would adjustable gas widgets (regardless of location) have any input on how soft the guns run? If all the work they do is unlock the bolt, then the felt recoil is due to the mass being shoved around by the barrel pressure alone, so how comes we can control that by playing with the gas block? Is the idea that by having less gas, we unlock later and there is less pressure in the barrel as more has escaped the muzzle? Link to comment Share on other sites More sharing options...
logiztix Posted January 6, 2015 Share Posted January 6, 2015 For what it's worth, I have experienced very different results with the RCA Adjustable Key between rifle and carbine length gas systems. I have set 5 of them up now, with a mix of 20" and 16" barrels. As expected, the gas in the carbine length systems was able to be dialed back quite a bit and function reliably. 4 out of 4 worked great in two DPMS, one Sig and one Bushmaster carbine. The RCA key was only successful in 1 of 3 of the 20" rifle length systems tried. To be fair, the old Eagle Arms upper wouldn't run 6 year old Remington UMC reliably before we started, even with new rings and a fresh cleaning. It was marginally gassed to start with, but has always run Federal .223 just fine. The other one that wouldn't run full open with the RCA key was a newer SIg 20" with rifle length gas. The only one of the three that would run Federal .223 with a rifle length gas system and the RCA key dialed for full gas was a DPMS bull barrel with an actual .223 chamber. It was adjusted down just a bit to lock back on an empty mag and run with a full 40 rounder and we called it good. My basic operating theory at the time was that 5" of barrel didn't provide enough gas that late in the game to pressurize the gas tube and do its job before the bolt unlocked and the pressure was dissipated. The carbine has 8" of barrel past the gas port and related time to pressurize a much shorter gas tube. The difference in performance between the two made sense at that basic level. It seemed less of a distinction between where the gas was choked down to how much it had to work with in the first place. I've also worked with adjustable gas blocks, the most recent being a second generation Syrac on a carbine. I originally tried the RCA key for a rifle length system. It seemed to me that on a longer length gas system that choking it down at the end of the line would allow the most consistent pressure at the key, making either a viable design for a carbine. If you think of controlling the flow of water, a small hose between two larger hoses makes it hard to develop consistent pressure at the nozzle. Where as, a longer gas system choked early has a much longer tube to pressurize past the choke point. Temperature and ammo pressure variance should have a greater effect on such a system, but that isn't my experience without access to a bunch of the same rifle to set up differently. It doesn't sound like there is a consensus to be had until there is some slow motion video to back it up. I would love to do it, but only have access to 240 FPS, which isn't probably going to be enough to catch what we're looking for. Link to comment Share on other sites More sharing options...
Dwight Stearns Posted January 6, 2015 Share Posted January 6, 2015 Let's do some basic math. There will be some assumptions for ease of calculation. 20 inch AR barrel = 0.5 meters (0.508 m for those that want to be exact) M193 55gr projectile muzzle velocity = 3,280 fps = 1,000 metres/sec Projectile spends 0.0005 seconds in the barrel (yes, I am ignoring acceleration, but I am keeping this simple, remember). Now, when the bullet just goes past the gas port, it has about 6 inches (0.15m) of travel left before it exits the muzzle. This means there is 0.00015 seconds until the bullet exits the muzzle and the pressure in the barrel drops back to atmospheric pressure. During that time, the gas has travelled down the gas tube and put pressure on either a piston or bolt carrier to impart kinetic energy to move it rearward. The bolt is still mechanically locked at this point. Now, let's assume a cyclic rate of 1,200 rpm (yes, I know AR cyclic rates are lower but bear with me). That is 20 rounds per second, or 0.05 seconds per round. Where am I going with this? The bullet has left the barrel BEFORE the bolt unlocks, meaning the pressure in the barrel is back to atmospheric and it is the rearward momentum imparted to the piston or bolt carrier (from the gas) that cycles the action. Yes, there is blowback pressure on the case while the projectile is still in the barrel, but that should be gone once the bullet has left the barrel. Mick Sorry Mick. Your math doesn't hold up. You are assuming that the pressure in the barrel drops from over 10,000 psi to +-14.7 psi instantly. The graphs I have seen indicate it takes longer for the barrel pressure to drop to ambient pressure after the bullet leaves the barrel than the time the bullet is actually in the barrel. Also the .05 cycling time would also include extraction, ejection, bolt slowing down from the effects of the buffer spring, bolt coming to a stop at the rear of its travel, the spring overcoming inertia, bolt accelerating, being stalled as it picks up the next round, bolt tripping the auto sear as it comes into battery, hammer spring overcoming inertia, hammer accelerating and striking the firing pin, firing pin being driven forward striking the primer, primer ignition, powder ignition, bullet acceleration and traveling down the barrel to vent had into the gas tube to start the process again. How much of that .05 seconds includes barrel overpressure which may effect extraction? Don't know. Link to comment Share on other sites More sharing options...
MickB Posted January 6, 2015 Share Posted January 6, 2015 (edited) Remember, the numbers are based on ASSUMPTIONS. The point of the exercise was to show that by the time the projectile has moved past the gas port and exited the barrel, the gas pressure in the barrel has dropped before the bolt unlocks. Projectile time in barrel past gas port ~ 0.00015 seconds Even allowing extra time for gas pressure in the barrel to dissipate, you should be at 0.001 or so seconds. REFERENCE (it's for 6mm PPC, but shows an example) http://www.frfrogspad.com/intballi.htm Another interesting reference. http://www.sadefensejournal.com/wp/?p=1093 Note that bore pressure ranges from ~6,000psi for a 20' barrel to ~11,500psi for a 10" barrel at the point the projectile exits the muzzle. Here is a reference from US Army tests that show barrel pressure drops to zero in 0.003 seconds in the M16 family (OK, so I was a little off. Sue me for using numbers from the top of my head! :-) ) http://www.armalite.com/images/Tech%20Notes%5CTECHNOTE104SEPT042014.pdf Now let's take the 0.05 seconds cycling assumption. If I use a 6-800 rpm cyclic rate (closer to the real deal), that number will be closer to 0.07-0.1 seconds Even parsing that into time for the bolt to mechanically unlock, you should still be at least one order of magnitude longer time for the bolt to unlock versus the bullet leaving the barrel and pressure dropping to ambient levels. Now you start to see a glimpse of what the designers are playing with. You can mess with reciprocating mass, spring rates, mechanical locking systems, etc. to retard the rearward movement of the action. The purpose is all the same - to make sure that pressure in the bore has dropped to a safe level before that bolt is unlocked I'm sure Mark will be along with more in depth numbers... :-) Mick Let's do some basic math. There will be some assumptions for ease of calculation.20 inch AR barrel = 0.5 meters (0.508 m for those that want to be exact)M193 55gr projectile muzzle velocity = 3,280 fps = 1,000 metres/secProjectile spends 0.0005 seconds in the barrel (yes, I am ignoring acceleration, but I am keeping this simple, remember).Now, when the bullet just goes past the gas port, it has about 6 inches (0.15m) of travel left before it exits the muzzle.This means there is 0.00015 seconds until the bullet exits the muzzle and the pressure in the barrel drops back to atmospheric pressure.During that time, the gas has travelled down the gas tube and put pressure on either a piston or bolt carrier to impart kinetic energy to move it rearward. The bolt is still mechanically locked at this point.Now, let's assume a cyclic rate of 1,200 rpm (yes, I know AR cyclic rates are lower but bear with me). That is 20 rounds per second, or 0.05 seconds per round.Where am I going with this?The bullet has left the barrel BEFORE the bolt unlocks, meaning the pressure in the barrel is back to atmospheric and it is the rearward momentum imparted to the piston or bolt carrier (from the gas) that cycles the action.Yes, there is blowback pressure on the case while the projectile is still in the barrel, but that should be gone once the bullet has left the barrel.Mick Sorry Mick. Your math doesn't hold up. You are assuming that the pressure in the barrel drops from over 10,000 psi to +-14.7 psi instantly. The graphs I have seen indicate it takes longer for the barrel pressure to drop to ambient pressure after the bullet leaves the barrel than the time the bullet is actually in the barrel.Also the .05 cycling time would also include extraction, ejection, bolt slowing down from the effects of the buffer spring, bolt coming to a stop at the rear of its travel, the spring overcoming inertia, bolt accelerating, being stalled as it picks up the next round, bolt tripping the auto sear as it comes into battery, hammer spring overcoming inertia, hammer accelerating and striking the firing pin, firing pin being driven forward striking the primer, primer ignition, powder ignition, bullet acceleration and traveling down the barrel to vent had into the gas tube to start the process again. How much of that .05 seconds includes barrel overpressure which may effect extraction? Don't know. Edited January 7, 2015 by MickB Link to comment Share on other sites More sharing options...
Dwight Stearns Posted January 7, 2015 Share Posted January 7, 2015 I'm not advocating anything. I just felt the math you were quoting was just way to simplistic. Curious if anyone can tell me how long it takes for the rifle to unlock once the bullet passes the gas port. Link to comment Share on other sites More sharing options...
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