Ep. 256 | DI vs. Piston-Driven AR’s - What’s Better? 

Please add more episodes with Tom to go into more details. This is the best drill down so far on youtube! Thank you.

PWS fan here. They've perfected the long-stroke piston in an AR platform. Super super easy to clean and very suppressor friendly.

Tom really seems to be a true fountain of knowledge. Great episode and will explained!

Sure wish there was more thumbs up icons as this had to be one of your best shows! Time was gone before I realized. Thank you boys for bringing great content.

I bought a Superlative Arms piston kit (the one in this video) to build out my 10.3 gun with a Surefire RC2 can. I will never go back to a DI gun for suppressor use. The piston system cuts down a massive amount of the poo poo doo doo that you will get back in the chamber / mag. Here are a few tips for people wanting a piston set up. 47:45 Carrier tilt can be compensated for with the right buffer tube. I run a POF tube that has ramps which extend into the receiver and support the rear of the bolt, thus preventing any issue or damage from tilt. Removing the gas rings from the bolt allows for the unlocking process to be a bit smoother imo. You don't have to do this with the SA system but it allows the bolt to move freely in the carrier and, in my head, means it should allow for an easier unlocking sequence. 50:30 As someone with 1000s of round on both systems, I completely agree. When either system is properly tuned there is no perceivable increase of recoil between the two. 55:58 These targets proved something I had in my head and never tried to prove. I have had no accuracy issues with my 10.3 piston gun...but I wondered if a longer gun with a midlength or carbine length piston system would be less accurate due to the piston being further from the muzzle. The scenario I thought of was that the piston would be pressurized and start moving rearward, pushing the carrier and creating forces upon the gas block / barrel, which would cause barrel whip / flex due to this force. The reason I have not encountered this issue on my 10.3 is due to the very small distance between my muzzle and gas port. - TLDR; maybe don't piston kit a carbine gas 16" barrel if you want 1 moa.

It's mind-boggling to consider the intricacies of the DI system and the fact that it was all designed in the pre-computer age. Also, now that I see all the variables that both types of guns possess, I now understand why (manual) bolt guns are generally considered to be more accurate. A job well done, guys! Thanks for such an informative podcast. 👍🤓

Those cross sections are a incredible. Answers a lot of questions for sure. Tom is also an awesome dude and an incredible shooter.

Awesome episode. This will definitely inform my AR maintenance going forward!

One of the best episodes yet! Would be fun to do this kind of topic on things like AK's, M1's even some odd pistols out there with rotating barrels...

I absolutely love my ADM UIC mod 2. I own a few high end AR15s like a Geissele Super Duty, DDM4V7, and PWS MK111 mod 1 and the ADM is probably my favorite, most accurate set up.

My inner Gun Geek really loved info in this one, THX

Mind blown! Thanks to all that made this happen

Your guest went above and beyond, WOW!!! What a fantastic test. I have always assumed that the piston guns were better because they tend to be more expensive. However as Townsend Whelan once said, "Only accurate rifles are interesting." It looked to me like the DI gun was noticeable more accurate especially with the suppressor.

Extremely well explained! I am going to bookmark this episode to forward to people asking me questions about "DI" guns.

Explained and understood. So well done. Thank you!

This was a fantastic breakdown! Ive researched this stuff to an obsessive level and everything he said was spot on. One thing that demonstrates the violence in the short stroke piston setup, is in suppressed SBRs. They are notorious for shearing bolt lugs. I knew of a guy who had sheared the lugs off of 3 or 4 sharps rifle company bolts in his.

one of the best podcasts in a while!

Lots of great discussion. Love the information.

This was excellent. I learned a lot about both systems that I never knew before.

Wow!! I absorbed all that info like a sponge! Very interesting. This was one, if not the best podcast that I have ever seen from Vortex Nation. I have a 300BK AR pistol that I want to experiment with. I always wondered if it was possible to convert a gas AR to Piston with minimum intrusion to the bolt system. This podcast gave me the confidence to go ahead and thinker with it.

One of the best episodes! Great job and great guest!

Tk’s for sharing all that knowledge with us 👍

Absolutely enjoyed this episode!

Thanks for all those things it's awesome knowing some of these things

Bring Tom back! That was amazing!

cool episode. Tom definitely did his research. PWS makes an awesome long stroke AR. Several side topics were touched on such as adjustable gas blocks, and different buffers. There are some other options on buffers that would be great to see in another episode, with the various types of traditional buffers compared with the hydraulic and captured recoil spring type buffers. I'm a fan of the JP captured recoil spring and have had good luck with them.

The Bruce Lee 1 inch punch is exactly what popped into my head at the same time as it popped into yours!

Thank you for another awesome video! 👍👍

That was great stuff! Thanks

Fantastic video, taught me a ton

Tom speaks the truth

Great info

Great content!!

Great episode. I would have like to see the velocities and ejection patterns between the two as well. It would be nice if both setups were configured to be gassed the same (relatively the same ejection pattern) to see if the velocities changed due to more/less gas being bled off from the system. My guess is that the accuracy difference is more due to change in barrel harmonics than moving parts though the piston system saw more vertical stringing which would be what I would have predicted if there was a difference.

Great info...I will never look at my BCG in the same way from this day forward lol.

Great guest!

Thanks tom

Militec is the best lubricant designed to prevent the caking up in guns. Soldiers in Iraq discovered it prevented their guns from jamming up in the dusty climate. Research, buy and try it, following the instructions for application. It's the first thing I do to every new firearm. First clean it and then apply the Militec system.

Great video

that's pretty cool. thanks

Great eppisode would love to see more detail oriented eppisode rhat break down diffrent subject like this. Such as diffrent hand gun styles like striker verse hammer fired, rooler blow back systems ect. . Only thing i think he should of tested was diffrent supressors. Dkd he use a flow through design with pretty mich no back presure added or did he use a traditional baffled design, or one of the newer 3D printed designs. Its just a thought because the back presure will deffinatly make a diffrence ive personaly seen it when i use a traditional style no matter the brand it makes my ddm 308 shoot like 4 to 5 moa when with just a como it shootd at pretty much 1.5 moa with decent ammo but with a flow through can i shoot 1.25 moa and even down to 1moa. So It would be interesting to see his thoughts on the subject of diffrent style cans and the diffrent operating systems and the effect they have on each other

Thanks to all 3

The piston system is “self cleaning” especially when compared with DI. The majority of the carbon doesn’t stop in the gas block and stay there because the force of the gas continues to the piston cup and that’s where the majority of the carbon is deposited. Then the buffer spring pushes the piston cup forward and the carbon is removed. The carbon goes through the gas block the same as a DI system so no more carbon is deposited there than in a piston system. Also, carrier tilt comes from loose tolerances. The piston rod can hit the same spot on the carrier if the tolerances are tight. This can pretty easily be monitored by any carrier wear.

The difference could be primarily barrel harmonics and a different set of components could reverse the performance making the piston more precise.

I like the Adams Arms gas piston AR's. I was interested in what they had to say about carrier tilt... via the AA website's FAQ... Q: What is carrier tilt, and should I be concerned? A: Carrier tilt is a symptom of a problem not the actual problem. The actual problem is sloppy or loose tolerances in the receiver. Our one-piece carrier combined with our bolt spring eliminates carrier tilt in even the sloppiest of receivers. For those who have normal mil/industry spec AR’s, the design of our system does not have an issue with carrier tilt. The fact is piston systems on the market vary from manufacturer to manufacturer we believe that ours has several design features that benefit over the competition in the market.

Eugene M. Stoner designs and guns before the M16 by C. Reed Knight Jr. Search for that article and read about, and see, the AR-12 external gas piston firearm

I have been using motor oil on my guns for a couple years. Chris from regular guy training was pretty convincing.

Good video. DI is not being used in any new firearms other than the AR platform military or civilian. The piston system is what is being designed into all new non AR weapons systems that I see. DI is a good system. Own both piston and DI. Piston SIG and LWRCI. My SIG 716 piston 308 shoots as good as any DI 308. I happily shoot it out to 600 yards. After shooting both systems since the late 90s, I will never go back to a DI gun. The modern quality manufactured piston guns are just as accurate. They are both good systems. A lot of people buy the DI because it's cheaper. Great info and video. Really enjoyed it.

I am a fan of the T91(Wolf A1) for an external piston option.

I've been using 15W-40 diesel oil for a while. A) it's basically free.99 for me B) it keeps a 6.6L turbo diesel running pretty well _and very, very clean_ . Every Duramax we've taken apart is pretty damn clean on the inside, so my rifle is pretty good.

DI AR’s are a internal piston system and piston AR or external piston system

Super presentation gaz verses piston.

I'm so glad I delayed correcting them about calling a standard AR a DI gun.

Now I understand the pluses and minuses of the piston conversion. Now I wonder how much suppressed shooting you’d need to do to make converting worthwhile (to keep the gun clean and enjoy not breathing the excess gasses)? I guess it’ll be personal preference.

Is there a notable difference of gas towards the shooter in these 2 setups? Deciding between the new sig spear 6.5 (piston) or the LMT battle rifle (gas)

I wonder how a Kyn Shot Hydraulic Buffer might affect the stringing as well as the additional kick on the piston gun? If at all.

Suppression; h3 buffer, piston of adjustable gas block for barrels 10" - 14.5" for high pressure issues cause by suppresors. Good to know

excellent break down on the dynamics. I'd like to see the math formula for the balance of (gas port) x (gas length) x (friction Q) x (BCG weight) x (buffer weight) x (spring Q) = n......oh I think I just did ....I'm working a 20" build with a Adams Arms short piston. outta the box it was apparently UNDERGASSED, short stroking/failure to feed. So after dropping the buffer weight to 2.6 oz and a lightweight spring, it still appears to be UNDER GASSED with 3:30 to 4 o'Clock ejecta of brass (which is better than when I started with mil-spec 3.06oz buffer and spring) and short stroke/failure to feed with steel. i'm moving to opening the gas port some.

ADM guy is pushing old information that was corrected several years ago, while also leaving out critical information. There are ski's on the bottom of modern piston carriers that have completely eliminated carrier tilt. Also the DI system needs to unload the bolt because the tension between the bolt and the carrier due to the tightness of the gas rings. A piston gun has no gas rings on the bolt, allowing the bolt to move very freely inside the carrier, causing no concern for the bolt lugs........ There's a very good reason why the piston driven HK416 is the most reliable form of the Stoner platform, and has been for many many years. As a matter of fact Eugene Stoner famously worked with knights Armament. Knights Armament only had the M110 contract for 4 years before our military decided to replace it with a piston driven design from H&K

I’m interested to know what was the piston was tuned too.

Someone in youtube was talking about "internal pistons" and "external pistons". Is that a real thing? Or wrong terms? Mixing piston vs direct impingement? What would be the "internal piston"? The BCG that is moved backewards, sealed by the gas seal? = DI.

shoutout to BGDefense for their Type-A short stroke piston system

I've never attempted to use motor oil of any kind on any firearm. I do use a mini-14. Which is a semi-direct impingement firearm. I do not like the idea of the gases in the operating system of the firearm. The AR requires the use of IMR powder. And if you do not know for a fact that that's what was used to load your animal you can run into some serious issues. When the military was trying to get ammo back in the '60s and Winchester said okay we can fill that order and they loaded up a bunch of ball powder for the ar-15, it increased the cyclic rate of the AR-15 by some 70%. And got a lot of men killed. The fact that the Firearms were literally dissolving in your hands during monsoon season, didn't help anything at all. That's why they put the coatings on the firearm much later. Now I didn't have a problem when I was in the military with the AR-15 a very early version that the Air Force used even though I was Army trained before I even went in the service, I fired expert Marksman in basic training and each time I qualified, the last time 40 of the rounds that I fired were all in full auto because it was eight below zero and it was a 20 not wind in our face and I wasn't going to be out there anymore than I did and I still fired a 3-inch group total into the target. When I finally purchased an AR pattern rifle it was a Ruger sr-762 and it fires wonderfully. I was originally oriented to the m14, it shoots just fine. I don't know where these people who say that these rifles are shooting four and five and six inch groups. I've never found one. They might be shooting four five and six inch groups. I've never seen one of those rifles that doesn't shoot under 2 in. And I do understand that they're out there because my particular gunsmith used to test those when he was in the Army in the early sixties and he said that 96% of all of the ones he ever tested would shoot sub 2 in. And that was with iron sights and he would just blindly pick a representation from each batch that came through the gates and never found what a small percentage that would shoot a little bit larger than that group. Then he ended up doing 4 years in Vietnam. As for lubrication, I might use a little bit of lubrication on firearms on occasion, usually in a break-in period. But every fire on my carry or intend to carry for any type of work purpose or if I'm going to shoot it on awful lot I use a dry Teflon lube and leave it the hell alone usually in a spray form. I've never had a lubricant based issue with a firearm yet. I started doing that with my stainless steel 4-in Ruger 357 revolver and continue doing that when I finally transitioned in about 2006 or 7 two semi-auto pistol eventually doing my primary firearm as a government model 1911 that I had hard problems so it doesn't need lubrication at all even though I did spray some dry Teflon lube and do that maybe once a year. Hard Chrome is very slick when the parts are having to operate with each other. The firearm that I carry was built by my gunsmith several decades ago and he fired a 597 out of 600 at the Army match on three different occasions and the next closest competitor with a government model would fire in the 400s. It is a supremely accurate Government model. And my gunsmith is one of only two Master gunsmiths in the state of Michigan. If you're going to use a motor oil, I would suggest that you get rid of the mobile one and go with Kendall motor oil or Amsoil. Kendall Motor Oil will take over 200° more heat than mobile one and Amsoil I know protects from where far better than mobile one. Mobile one is actually not that good as oil in actual testing. It is a good functional synthetic motor oil. That's it. Do some study on motor oils tested against each other and up your game just a little bit.

Double Like 👍🏻👍🏻 Button !

The piston is the future just runs cooler cleaner longer

Maybe a crazy question; I know my whole BCG will get carboned up, just normal for a DI weapon. Question being, why doesn’t the gas tube itself carbon up like the rest of the operating system? I can run pipe cleaners up inside the gas tube and have them come out clean.

Edit... seems like it was the original design but maybe I was thinking of the AR-12, search this article... Eugene M. Stoner designs and guns before the M16 by C. Reed Knight Jr. Gene Stoner's original AR design was a 7.62X51mm (.308 win.) gas piston firearm. It had a piston rod attached to the bolt carrier as I remember, (similar to an AK ) The reason he changed to a gas impingement piston design, and the 5.56 NATO caliber, was because that is what the US military was interested in, they wanted the firearm to be lighter, and the gas piston design was just over their weight limit, and they wanted the smaller caliber so that more rounds could be carried without a weight increase etc.

10 months and only 742 likes... It's a shame. Personally, I would like a follow up with fine tuning of loads for each mechanism to see it there really is a difference in accuracy.

The AR platform was designed for the internal piston and works very well. Putting an external piston on the AR platform creates more problems than it solves..Colt tried this in the early 1960's and found it solved nothing and created more problems than solved, which is why Colt never looked back..Fools and their money comes to mind lol..

FUCK YEAH TOM

50+ years to 'Innovate' and we are left with "piston vs. DI" and "ambi" .... So slightly less dirty bcg with slightly more recoil and front heavy weight. And everyone gets to pay more for Lefty's which amounts to 11% of the population. And of those 'wrong handed shooters' ½ shoot righty because they were taught right handed is better... Saving everyone an hour of time because nothing has changed since they've 1st been implemented.

Actually think of an M1 Carbine with a rod attached to the tappet

We are one year away from the customer picking their gas port size from these barrel companies

So choosing one over the other depends as always on the purpose for the weapon! DI for shtf where parts may be scavenged. Piston parts may be scarce in shtf.

One is not better than the other...both can be used in a bad gun and be useless. Both are tools in the same tool box... Love these deep dives though 👍🤠⚔🗽

Like to see this, from a machinist point

So, in today's world, there has to be a speed tuning software that takes into account -all- the variables. Like including the well tuning screws for adjusting dwell as a function of the dynamics on the BCG itself. I can understand propriatory information ...and yet? Anybody? (please!)

CONFIRMED! Bruce Lee invented the short stroke gas piston system in honor of his one inch punch.

Milliseconds

al gores rhythm

How are the hosts of a firearm podcast so incredibly ignorant as to how an AR15 functions? How have you never learned the action of a DI AR15? How do you not know how rotating bolts work? Also how do you not know the difference between short stroke and long stroke pistons? Bizarrely ignorant hosts!

It's not correct that the piston knocks the bolt all the way to the rear. It merely moves the carrier rearward enough to unlock the bolt, and then the leftover chamber pressure cycles the bolt.

My AR does not like and actually will not operate dry.

I have an LWRCI SPR an POF 415 edge and a SIG MCX Virtus and a Tavor 7 all piston I have a DDM5 V-4 and DDM4 PDW and DDM4 .300 and I have to say all my piston guns last longer with each cleaning they run way cooler I think we need to switch to piston guns. DI is dead folks

13 mins in, and I can already tell this is nothing more than a glorified ad to sell piston kits.

There are anti tilt skies, that is a anti tilt carrier. False with recoil impulse on the piston being sharper. There’s gas relief from a DI carrier that can push the rifle to the left.. some things talked about are half truths.

This isn't even a conversation - piston is always better and more reliable!!! What is the primary enemy of a weapon? Heat. What produces more heat? DI. Even 7m thumb over bore Magpul Kool aid drinking metrosexuals have come to realize that. What is the second enemy of a rifle/carbine? Fouling. DI guns foul to the extent that they are analogous to weapons using black powder versus smokeless powder (piston guns). What kills the DI is serviceability - use a DI gun in a sandstorm or an environment where ash and heavy smoke are the combat reality. Once that DI gun has its gas tube clogged - it has to be taken to an armorer to get unclogged. In a piston gun unclogging a gas tube is often just a different gas setting or cleaning your weapon in a worst case scenario. Only THUMB OVER BORE POGUES CHOSE DI OVER PISTON GUNS. DI for police and recreational civilian applications is adequate, as long as you keep it clean, unfouled, running slick. In a combat situation you should not run it hot - only as a last resort suppressive burst. You must dutifully keep it clean. You must mind your environment and debris. Only a thumb over bore poseur like Garand Thumb would pick a less reliable and greater maintenance system like DI over a superior piston system.

Lol...really.DI? Seems to be internal position vs external position maybe lol..but who wants to understand guns lets keep teaching the wrong things for another 50 years ... Baffling kinda

Funny, weren't piston driven AR's suppose to take over the AR industry by storm a few years back? I almost always shoot my Ak's in action shooting events, so I love pistons, but I'll always keep my AR's with the same format they are in right now, direct impingement.

ar is a 4 moa gun by mil spec standard.

DI

i'd rather not spend 2 hours cleaning a DI rifle. Piston4Life

Which is Better ? I know your NOT talking about your Lungs. If you want to know ... # 1 ) Watch a video of how much spent toxic-nastiness comes out of the breach of a "DI" Gun into your face. # 2 ) Read about all of the toxic compounds that comprise all of that spent toxic nastiness you are breathing into your lungs. THEN answer the question .. "Why ?" .

Oh wow we are alive……🫠