Firearms Facts: DI vs Piston

welcome back everybody this is Eric and Chad here with Iraq veteran 8888 today we've got another firearms fact episode for you today we're going to be getting into the ins and outs of di versus piston operation a lot of people tend to have some confusion over it so hopefully this video will serve as a reference to hopefully some of you guys that are stumped can be pointed in the right direction on this whole thing if you want to learn more about firearms technology definitely check out SDI they are a great group of people they got some great programs at their school they take GI Bill if you want to go further down the rabbit hole they're definitely a great resource to check out so give them a look if that's something you want to look into it's definitely worth checking out so I guess I'm gonna let chat in his own words just give you a super super brief and and and straight-to-the-point explanation of the essential difference between these two different phenomenons they're happening here you know you say di and I've had like direct injection for car engines on the brain because I've been working on cars the past few days so that's all I can think about is direct injection alright so di is direct gas impingement okay it's the common system that's associated with like the ar-15 is the most predominant firearm that's associated with direct gas impingement so the main difference between di and piston is that in a DI system the expanding gases behind the projectile as the rounds fired are picked up forward down the barrel and then they are set backwards and then they are impinge on the action itself to cycle the firearm on a piston system the gasses themselves are trapped in say a piston cup and then a long rod or other other mechanisms that we'll discuss further in this video the the gases are impinged upon that rod itself and then the bolt carrier comes to the rear and the action cycles no gas safe or the gases that just blow back during the action itself of firing wind up in the receiver that's one of the big differ is between di and piston as well is that correct ass impingement systems as a lot of extra carbon deposits such that wound up in the action of the firearm with a piston system typically they do run cleaner but there are some exceptions for sure yes so the common analogy that's given on the DI gun is that a DI gun poops in its own mouth and it it is true okay so with a DI you can even separate di into a couple of different areas as well all right in front of me we have a AG 42 human alright the human is a direct gas impingement gun true it was a true direct gas impingement gun because the gases literally are directed directly against a cup on the bolt face okay it can't get any more simple than that same thing with our French rifle down here the MAS oui oui yeah that's a forty-nine mass 49 whatever they call those things I can't remember all my gun lingo but the French rifle is the same way okay it uses a long tube and the gases are directly impinge literally against a cup in the front of the bolt face okay so that's a true direct gas impingement so you know all these people say oh Eugene stoner direct gas impingement oh the a arms so futuristic I mean don't get me wrong the ar-15 was a pretty interesting invention I mean what's safe to say it's quite successful okay it's a very common use rifle however it wasn't the first rifle to use direct gas impingement so when we look at the ar-15 Chad so we're look at the ar-15 if you guys follow Tim over military armed shelling you know that he started a huge dumpster fire with some recent videos about the AR not being a true di which technically speaking it is not the gas is picked up and it's run down a tube okay the gas tube here but it impinges upon a piston area inside of the bolt carrier group itself so you have a separate bolt and a separate carrier and there are piston rings the gas rings that trap the gas and then allow the action to delay and unlock so in the truest sense of the difference between direct impingement and piston this is kind of a combination of the two systems and the AR and just it's it's bare bone operation has been very very reliable over the years it's really come to fruition and it it's really a great system I mean the guys over in range do these mud tests on various rifles and the AR has trumped nearly everything it's like oh well just put some mud on the thing you know it'll choke up the ache a lost to this definitely check out easy Faro they're they're great dudes but Tim did a very very detailed video chase over there at capo custom and all and they have a lot of information about this system itself we won't really go into detail but just know this is a combination of the two systems in its truest form all right so now we'll go down the rabbit hole of piston systems okay oh boy so with piston systems you can get away with a pretty good bit okay in terms of how they're made there's a lot of different ways to trap that gas okay but the basic premise behind a piston system is that the gas stays out of the action that's important for a couple of reasons okay one reason is because obviously it's going to make the system run cleaner over a longer period of time now a lot of people depending on the piston system in question don't like piston systems because they don't suppress quite as well well it just depends but what I'm saying exception so that's it I can suppress this a kay right but what do I have to deal with yep that's loud right not only that but also the excess gas in most piston systems is expelled through little pores that are in the system itself once the once the cup of the piston stands past that point when it's going at its full rearward momentum the excess gas isn't needed in the system so it expels out of the front and this phenomenon was commonly known as piston pop Ryan on certain rifles especially probably like the augs the Steyr aughh is the worst example I can think of with this but it has very horrendous piston pop and being such a short plat it is extremely wild suppressed at the year if we dig we're gonna get on that and a little bit here in terms of the suppression now with this system is a long stroke gas piston all right because you have a large piece of reciprocating mass whereby the piston is attached directly to the carrier and if you think about it Mykel coalition akov when he designed this he was a tank commander and an engineer and a bit of a mechanic so he thought okay well I'm just gonna make a really simple machine right so how do cars work those Pistons going up and down and that exert rotational axis okay same type of thing all we're worried about is linear axis of travel with gas being exact it against this cup okay and it's it's got a relatively loose fit so it's not a very efficient system in the a K but it's made that way so that it's really you know can handle a lot of abuse and not being cleaned well and copper buildup and all kind of crap which we've proved in other videos a case you know pretty good system so you have a long stroke gas piston then you can get in down to the rabbit hole of all different kinds of different systems then you have what would fall into the category of a short-stroke gas piston whereby you use a short tap it's or short gas system such as m1 carbine m1 a is another good example m14 also uses essentially a short tapping system so with this system the carrier it's this long piece of reciprocating mass not unlike the a K but instead of the gasses exerting directly against the carrier okay on an Mir teen opera opera okay m1 garand would be technically long stroke technically cuz it's just that big huge hot rod but the m14 and the m1 carbine used a tappet system it's literally just a little puck yep in there that pushes back and forth it now seals the gas and then traps it mm-hmm there you go yeah and it's a really simple kind of thing right so then getting it a little bit down a different into the rabbit hole you might have a short tap it system and the saiga-12 twelve essentially uses a very similar type of gas system to the m14 and m1 carbine whereby it uses just a little puck in fact this one's dirty so you're not gonna hear it probably but if I yeah it's a little but when when a Saiga 12 is clean you'll hear that get that tap it moving back and forth and there's a little puck okay and that puck captures the gas and then exerts a lot of force directly against the front of a long-stroke up rod now weird thing about that is the Saiga 12 still uses an a K style op rod though okay and that's the strange thing that a lot of people tend to not consider it's a shotgun okay to 12 gauge you still have that area okay but I believe what they're running into is they were having problems getting these things to cycle just picking up the gas right on the cup of the piston they had to use a puck system to capture the gas to have more surface area on the front of the puck to make it push back harder and then it actuates it well it's it's all about gas volume 2 because shotgun shells are a low pressure cartridge more or less and that's why the gas system itself like the gas block on Saiga shotguns and other semiautomatic shotguns is so large because it's like a high volume low pressure setup whereas on a rifle you'll have a smaller gas blocking gas area and Cup because you're at a higher pressure lower volume so that's a perfect place for us to talk about suppressing these systems now you know the cool thing about a DI system versus a piston system piston systems are cool because of the way they capture gas right now this is exactly a cutaway that now this is one of our uppers from our meltdown alright we melt melt it down wind Alexandr arms piston uppers here but you can see that there's a cup that is actuated against you know an op rod then the gas is generally captured in this area but we also would we have an adjustment we can adjust the amount of gas flow and really control exactly what gas is being introduced to the system so for suppressing purposes Pistons are awesome because it gives you a lot of flexibility to adjust the gas walk now when you get into a DI you get into maybe just a little bit more complexity in terms of getting the system to run at peak performance when you're trying to suppress it however chad has a little more experience with that always so every so the big thing with suppressing systems between you know di and a piston is slowing down bolt thrust okay when you put a traditional suppressor on the end of the rifle typically you're gonna get what's called back pressure back pressure increases the rearward momentum of that gas it's traveling faster so to slow that down and a traditional like AR for example that uses a DI system a combination system you normally would run either like a heavier spring a heavier buffer or combination thereof the two in some rifles you could have an adjustable gas block like I've got in several rifles I have the superlative arms adjustable di blocks and they can either restrict the gas flow or they can do what's called bleed it off and then bleed off the excess gas out the front and I've found that certain rifles suppress better than others with a piston system on honestly the superlative arms piston system uses a long piston rod and it has the cup built into the end of it and basically the gas just gets picked up and exerts pressure on the cup pushes the entire rod and then that hits the bolt carrier itself and sends the bolt and carrier to the rear of cycles action however since you're not getting all that excess gas flowing out of the the flow ports in the carrier itself like on a DI system you get this puff of gas out of there where the excess gas is expelled right there by your face therefore increasing the sound pressure levels at the ear the piston system the superlative Arms specifically is quieter at the ear and all the testing that I've done which is really cool and it's a lot cleaner to like hear I mentioned earlier the system the piston systems run a lot cleaner just because you don't have all that gas coming back into the action and also if you see in some of the meltdown videos where we've used the thermal footage between the DI setups and the piston setups you can clearly see that heat flow doesn't make it back to the receiver and the action as fast as it does in the DI systems it stays a lot cooler and you can clearly see the evidence of that in the meltdowns which is really cool our tests have clearly proven that heat destroys a gun hmm enough heat enough friction and that heat and acting itself against the firearm for long enough you're gonna start melting things you're gonna start drawing temper you're gonna start getting the barrel to droop the system to just tear itself apart so heat is the enemy when it comes to how these firearms absolutely I you know so I guess the big the big question that will end with on this video is which system is better di or a piston system I think that both systems serve a essential role depending on what you're trying to do it is a tool specific type of cam that you come to ok D eyes are great one thing that's nice about di is the recoil impulse is super super nice I mean shooting an AR is it's just such they purr like a kitten they just do not have any recoil so you do get less recoil out of a DI system and and especially in a rifle linked system when those gasses are expanding violently rapidly and everything but they are cooling and they are slowing and it is a less violent expansion of gas over a period of time versus a shorter gas tube that has to get that gas in there really quick there's not as much time for that to occur so that you know they have such a nice recoil impulse on a rifle linked system they're not without their maintenance requirements you do need to make sure you keep them clean and keep them well serviced but you know I would see a piston system may be running a heck of a lot longer without maintenance so if that is a concern of yours and you're not concerned about recoil impulse then maybe you want to suppress a gun as well maybe it's a hunting rifle that you take out and hunt pigs with every weekend and you only want to clean it every couple of months or something you probably get away with that yeah big big takeaways for me just the the main comparisons of contrast mainly in contrast di systems are typically less expensive especially in like ar-15 less moving parts less to worry about you literally have gas tube and then your standard karyam they are with a piston system you've got a different gas block you have the piston cup itself and actuator rod if that's the way it's set up plus you have a special carrier that has instead of a gas key on the top of it you just have a solid machine block for that piston to actuate upon typically those systems are definitely more expensive yeah oh that's that's one big thing but certain rifles you know they were really designed from the ground up with one system in mind I mean take like the FAL for example it's always been a piston rifle you know and it's just rugged dependability ultra liability you know just great great setup I couldn't imagine a rifle like an FAL being a direct asset management but you look at the AG 42 and it's been stellar never had a single problem out of these rifles and the Hakeem's and the what's the little uh 7 6 - or she the rashid the rashid uses the same system as well because they were all based off of the same design by Erik Eckland and it were um it works great but the the biggest thing is really like we mentioned cost reliability piston systems typically could be seen as being a little bit more reliable in the long run without preventative maintenance they can go a lot longer most of the time without routine cleaning than a DI system but if you take care of a DI system especially an AR it'll serve you for ever I have one more one more thing to add to this discussion and one let you guys get back to your day you cannot deny reciprocating mass there's no such thing as a free lunch in physics and we look at the scar the scar is one of my favorite rifle I love it but it has a humungous like two-pound bolt carrier okay and that reciprocating mass you know you cannot use no such thing as a free lunch and physics you know you have to deal with it when that that heavy reciprocating mass moving back and forth you know it does have a bit of recoil it kicks harder than a lot of 308 might kick and then also it beats up optics because a lot of people think oh well that bolt comes to the rear and it stops right oh well that's what's destroying the optic no it's when it comes to arrest as it goes forward that destroys the optics so some systems will power the crap out of your optics and the scar is one of those I love the scar platform it is a wonderful rifle they're accurate they're reliable you know they got a suppressor setting they suppress quite well and man just they're they're just wonderful rifles but they're not without the quirks so don't think that just because you drop four grand on a rifle that all of a sudden oh it's the best thing since sliced bread I mean the scar is cool but it does beat up optics and something to consider you've got to put a robust optic on a scar because you can't deny the reciprocating mass of that huge piston carrier okay guys thanks for watching today's video we hope you enjoyed it we love making these types of videos that we definitely want to take a moment to thank all of our patreon supporters you guys are awesome thank you so much all the folks who purchased man cans or shirts merchandise over on the website all those funds go right back into supporting the channel thank you guys so very much for the support thanks for watching we hope you learned something many more videos on the way we'll see you next time see you guys [Music]

Channel: Iraqveteran8888

Views: 116,271

Rating: 4.9417171 out of 5

Keywords: iraqveteran8888, iv8888, piston ar-15, piston ar, ar-15 vs ak-47, ak vs ar, direct impingement, piston vs di, adams arms, di vs piston, firearms facts, firearms fact, piston ar 15 vs gas, piston ar vs gas, direct impingement vs gas piston, direct impingement vs gas piston suppressed, gas piston, piston gun, piston rifle

Id: vXhLEhzsyQo

Length: 18min 57sec (1137 seconds)

Published: Wed Aug 07 2019