Just read on the HKPRO forums regarding the MR556 that piston ARs have a noticeably sharper recoil feel compared to DI guns. But just how much worse/noticeable is this recoil?

87 times.

Basically it's whatever additional force is created by the weight of the piston cycling, that's it.  
Is it noticeable?  Meh, a little.  Kind of like an overgassed DI system.  It can be minimized with tuning.  
Mainly it's just another something for the piston haters to beard the lion with.

I am no expert and can only speak for my experience with the one piston system I own and the only one I have ever shot. The recoil is noticeably lighter (less sharp) than my DI systems I own. I am a fan of the PWS MK116. If you buy it you will love it.....Well balanced and muzzle rise is almost not even noticeable. The only problem I have had after buying the gun is resisting the temptation to buy another as they are not cheap.

Perceived recoil depends on how overgassed the gun is (or isn't), and has absolutely nothing to do with piston/DI.

To me a DI AR feels like its a slow push compared to a Piston gun.

I shot a full auto M4 style rifle with an AA piston and it felt almost the same as a carbine length DI gun.

It is hard to make a comparison since I doubt anybody has absolutely identical guns except for the piston/gas system. Just too many variables to make a reliable comparison.

my LWRC m6a3 uppers have been over gassed and push more. i cut a 16 back to 12 and it still ran perfect bit feltore like a properly gassed DI.

hey are cleaner though.

I notice that it's..... different. I would never say it's sharper or harsher. At least not in any sort of manner that affects anything as far as shooting goes.


Seriously.... it's 5.56mm. Anyone complaining about an increase in recoil throwing off their followup shot probably can't shoot rapidly for a crap to begin with, and probably needs to go back to shooting air rifles with the Boy Scouts.

Still using both piston and DI with matching barrel lengths,

Pistons can feel more in felt recoil, Hk416 I find notably more since it is over gassed for extreme reliability (so they say). All my AA guns It does not feel more but feels very different. The recoil is felt more over the barrel due to the rod going back and forth than in the butt stock like a DI gun.

As far as you should not worry about the general lack of recoil with 5.56 to begin with. If you are wanting to get your shots down to say 4-5 a second at a target around the 5-10 meter mark (with good hits), you must dampen the felt recoil to do so. All serious 3gunners have to.

The easiest way is to install a comp, but of course they are generally loud and gassy and for a tactical gun are not that practical.

To keep your gun more "tactical" and address recoil I recommend specifically for a piston gun either hydraulic buffer (yes I brought up the dreaded hydraulic buffer) I know some one will now post the one photo of a broken Enidine buffer that has been floating around the internet for the last 10yrs. But seriously Kynshot makes a great hydraulic buffer, Enidine (I have two) make great ones but are a military only item now. Another great option is the JP captured recoil buffer spring.   I do recommend staying away from Crosshair hydraulic buffers I broke one under 2,000rds.  

Using either the hydraulic buffer or JP captured spring  I find really takes the edge off the felt recoil especially with piston guns and makes them feel exactly like their DI counterparts.

 

Just to throw it in; To get super fancy there is also the FERFRANS system, it uses a specifically designed bolt carrier that slows the rate of full auto fire to a more manageable rate. The added benefit it cuts felt recoil on semi. The only problem I do not think FERFRANS is sold commercially so they are very hard to get, note the emblem on the bolt carier:

     

I'm actually lucky enough to have done exactly this.  Buddy and brother decided to do builds at the same time.  Brother wanted a piston gun because he liked mine, buddy was Army and was comfortable with the DI system.  They both built on the same receiver sets with the same barrels and handguards.  Only difference worth mentioning was the buddy went with the Marpul PRS, brother went UBR, but there's not a huge weight difference between them (the PRS is probably slightly heavier but not by much).  The guns shoot with the same accuracy, but as far as recoil goes it's not really "more" or "less" but just "different."  The impules seemed a hair longer with the piston gun, but more immediate, while the DI gun seemed to have a hint of delay.  This made perfect sense though as the piston gets acted upon by the gasses immedaitely, while the gas has to travel a bit to get to the BCG with the DI gun.  So the concensus was it was more about feel and less about anything else.

The above scenario is about as close as you can get anecdotally.  I'd say the only real way to determine this would be to build identical ultralight ARs to maximize effect by minimizing total weapon mass, add or subtract weight to account for any differences due to system types (although this is another area haters try to complain about piston systems, but the weight difference is essentialy a hollow gas tube vs a solid rod, and that isn't much), and scientifically measure the two.

Ultimately in the real world there are far too many variables that matter from other guns.  Length of gas system, buffer weight, reciprocating mass, port size, gas regulation, total gun weight, shooter sensitivity.

i have an MR556, MR762 and an LWRC M6A2 SPR as well as several DI comparable 308 and 556 AR's. I haven't noticed much difference in recoil impulse.

Between my m6a2 and a probably overgassed carbine buffer DI gun, the m6a2 is noticeably smoother to me. The biggest weight difference is the di gun has irons and the lwrc has an eotech. It doesn't seem to me the recoil difference is even worth noting.

Recoil is indeed different, but not necessary sharper. Our DI proponent that tried to talk me out of getting a piston gun, found my Ruger sr556 surprisingly smooth and soft.
In the end I tried a few DI guns, and I prefer the recoil of a piston gun. I found it more predicitable than for a DI gun, a bit longer but smoother, giving me more control. Of course this could be totally different depending on the piston set-up, gassing etc.. but I would say just go and try for yourself.

This.

I've shot a few PWS piston guns.  One thing that shocked me was the recoil seemed significantly LESS  and SOFTER than that of DI guns.

But, that probably has something to do with the PWS FSC and Triad compensators which were on the guns.  Those seem to be very effective at controlling felt recoil, muzzle rise, etc.

HighSpeedSteel

I cant tell at all.  Perceived and real can be quite different.  Energy being energy, and it's pretty instantaneous, I'm not sure one could tell.  Muzzles and springs may change that, but side by side I can't tell.

Meh, its a little noticeable on my m6a3 but I don't even notice on my lmt shorty.

my Adam Arms piston set up w/ 11.5" barrel and Allstar Tactical delta muzzle break in 5.56 has less recoil than my dad's 16" chiappa .22lr ar.  just saying.  Depends how you build it.

I can only speak for LWRC piston ar's and FN Scar 16s and the recoil is considerably less than any of my DI rifles.  Recoil feels more linear if that makes since.

I have identical setup BCM DI and Huldra GP rifles. Both 16" middy with H1 carbine buffers and the same grips/stocks/triggers/sights.

Shooting side by side, they feel practically the same, the GP maybe just a hair sharper. The recoil masses are the same, so the single variable is the velocity of the BCG. If they are ported the same then I can see is the surface area of the piston vs the gas chamber in the BCG accounting for the slight difference in BCG velocity.

Thanks for posting that. There's too many variable for me to tell, since some of my guns may be over gassed a bit, or lighter/heavier in weight, so it is tough to compare. I did not notice a major difference with my 20" rifle piston kit, but I thought I felt a bit more of impact or movement in the rifle which I attributed to the piston rod movement. It was slight enough that it just could have been me focusing more on it.  

But any claims that it either greatly increases or decreases felt recoil, I think are an exaggeration.  You could shoot some lighter wolf 223 one day, and hotter 5.56 loads the next and get all sorts of different perceptions. I think jhend's assessment is right on.

I can try to do this. I have two LMT MRP CQB 16" rifles, one is a piston and one DI version. I also have and have previously owned other piston rifles and all piston systems are not the same in recoil/cycling impulse. As for the LMT's, the DI rifle has a much "smoother" recoil impulse than the piston version. The piston version cycles more aggressively (not violent, but it's a more sharp/violent action than the DI version). The piston rifle is also somewhat heavier than the DI version, though it still feels like it has a stronger/sharper recoil impulse (the piston rifle tends to wander slightly more on target than the DI rifle during rapid fire strings, it takes a bit more effort to keep it "still", again...minor, but mentioned by virtually everybody who's tried them both). I like piston rifles due to the cleaning benefits and the cooler running aspects, but from a shooting perspective I prefer shooting the DI LMT over the piston.

Continued:

Both of these rifles have the same trigger, same muzzle brake, sling mounts, etc. The only difference is in the optics, the piston has an Aimpoint Comp C3 in a Larue mount, the DI has an Aimpoint H1 micro on a Larue mount (about a 5-ish ounce difference in optics). Fully dressed the LMT DI rifle is 7 lb 10.5 oz, the piston rifle is 8 lb 6 oz (that's the total weight of them including the difference in the weight of the optics). I believe the Aimpoint micro H1 and Larue mount to be approximately 6 oz, I believe the Comp C3 and Larue mount to be closer to 11 ounces, but I don't have an exact weight on it (somebody here might know?). These werel weighed using a Lyman digital trigger pull gauge that was zeroed vertically (to adjust for the weight of the "hook") and the results were repeatable, so they would seem to also be reasonably accurate. If other data disagrees, then that might suggest that the gauge isn't as accurate as I believe it to be.

The Barrett Rec7 (Gen 1 and Gen 2) seem to shoot slightly softer than the LMT piston rifle and the LWRC M6A2-SPR has a much softer recoil impulse (cycling action?)  than any of the rifles listed above. LWRC has a somewhat different gas system that picks up the gas pressure a bit farther from the chamber and uses a very different piston design that seems to "trap" less gas and cycle much less aggressively.

Note: The descriptions above are my best attempt to differentiate in type the differences between the feel of these rifles. Aggressively, violently, etc are an attempt to differentiate between the differences in feel. I'm not saying that any of them are particularly violent to shoot (it's 5.56, it's not exactly a 375 RUM).

I have shot a DI and piston gun side-by-side and, quite frankly, I cannot feel a difference.  My friend who shoots DI guns regularly thought my SR556 shots slightly softer, though.

The recoil impulse is affected by many things, most significantly the size of the gas port and the resulting energy of the action cycling. Piston/DI makes very little difference; the variation between individual guns in more significant than the mechanism used to push the bolt carrier back.

I personally have also shot DI and piston side by side. I've had a chance to do this with both my ADCOR and M6 IC. Out of both of my pistons my IC in my opinion is the best one although other people who have done the same sometimes prefer the ADCOR. Comparing my favorite out of them the M6 IC, next to a DI I find the sharper recoil pulse significantly more manageable than the long slower push of a DI rifle. Again this is all my personal preference but as I have said I PREFER the recoil of a piston rifle over a DI. For me my follow up shots are much faster with my M6 IC. It's highly likely the fact is due to the neutral axis of the KAC MAMS I have on my M6 IC and the fact my IC is also more front heavy than most DI rifles although shooting from a bench somewhat negates that.

When a friend of mine went out to the range with a bunch of us last weekend he wanted to do speed runs. Out of all the AR's we had out there his shining choice for this was my M6 IC. His best run of the day that we recorded was 30 rounds on paper at 50 yards in 7 seconds.

For comparison this is one of the DI rifles another arfcommer brings out that he lets the guys shoot. It's relatively stock compared to both my piston rifles so it's not really a fair comparison as someone stated earlier there were just too many variables to take into account but on a performance level it shows what happens when you dump a lot of money into an AR compared to a stock AR. You do indeed get what you pay for.



and the M6 IC for comparison:

Coming from many years of pistols, bolt rifles, and a 9mm carbine, last year was my first time to get into AR platforms.  My first rifles were two Armalite AR10's in .243 and.308.  My initial shock and satisfaction was from the fact that these two rifles shot ridiculously soft.  Compared to a .308 bolt rifle, the AR10 was an "all day" shooter...a very pleasant surprise.  Later I got an LWRC M6(5.56) with 16" barrel and love that rifle too.  I just replaced the .243 barrel AR10 barrel with an Armalite 16" lightweight .308 carbine barrel.  I also installed an AAC muzzle brake.  Yesterday I shot the .308 carbine and LWRC during a lengthy scope sighting and practice session at our range.  While I consider neither of these rifles to have notable recoil, I gotta say the LWRC is no softer than the .308 carbine.  The LWRC only has a flash hider.  Again, I stress that neither of these rifles has anything close to a harsh recoil.  However, I was surprised the 5.56 LWRC wasn't "softer" shooting.  There was no problem with quickly reacquiring the target during fairly rapid fire with either the .308 or the LWRC.  Now, please understand that I don't own a DI 5.56 AR to make an exact comparison.  The AR10's are, of course, DI rifles.  Don't get me wrong...I have no thoughts whatsoever of parting with this LWRC.  It's an utterly awesome rifle.

On this overall issue of 5.56 recoil, at least in a rifle sized weapon, I'm of the opinion that they don't have any harsh recoil...or even any that really interferes with quick target reacquisition.  I also own a Steyr AUG(gas piston 5.56) and a Kel-Tec PLR16(gas piston 5.56).  The Steyr is also a really smooth shooting rifle, maybe a tiny bit less than the LWRC IMO.  If you want 5.56 recoil, then the PLR16 will provide a decent amount of that, but what would you expect out of a 3.3 pound pistol with a 9" barrel...LOL!  It is, however, still quite manageable and easy to shoot...about the same recoil as a mid-compact 9mm with +P ammo.  Some of these discussions point out how subjective recoil can be.

its like a 50 BMG

Mine is the Adams Arms rifle length piston system on a 16.5" Voodoo Innovations barrel. It fires extremely smooth. Recoil is less than my DI rifle has. The rifle was receiver accurized also by CIV Tactical. The rifle has the ALG Defense Advanced Combat Trigger. The trigger has a really crisp break. Probably the best $65 that can be spent for an AR upgrade.

Since my last post about my LWRC M6A2, I noticed a cosmetic issue with the complete factory upper that I purchased.  I took it back to my supplier, and they inspected it.  They agreed and gave me a new complete upper as a replacement.  However, the replacement is an M6A2-S which is normally referred to as a "stretch" model.  It's still a 16" barrel, but the gas block is further out on the barrel as a mid-length model.  This is supposed to provide a "softer" shooting rifle with better target reacquisition and perhaps better long term wear.  This upper is $200 more than my standard M6A2 model was, so I guess it wasn't a bad deal at all.  I haven't had a chance to shoot this rifle yet, but I wonder if it will actually provide a smoother shooting weapon?  Anyone else get to fire both of these weapons to tell?  This thread is about recoil, so I figured it wouldn't hurt to keep this one here.

I just got the Adams Arms Tac Evo. Never had a piston before. The recoils is a bit sharper and definitely more abrupt. I have 3 mid length guns with H2 buffers. Going to the piston feels almost like switching from underpowered steel .223 to a hot-loaded 5.56. I find it unpleasant. With no magnification, it doesn't make a big difference. But staying on target with a 3x scope while standing up takes more concentration.

And that has nothing to do with piston/DI, it just happens to be more overgassed than the DI guns you have. The "sharp" recoil is the BCG+buffer hitting the back of the buffer tube. You can make the recoil of either DI or piston sharp and unpleasant if you adjust the cycling energy too high.

My Ruger SR556 kicks less than any of my DI guns, but it's heavier too, and 5.56/.223 doesn't kick enough to matter anyway.