watching the HK416 youtube videos I notices when they use a can the gun works fine.
does the piston negate the use of an adjustable gas block?
does the piston negate the use of an adjustable gas block?
- Thread starter shootist2004
- Start date
I first added the Thunder Beast CB9 to my DI and had the typical dirty BCG and additional gas in my face. Put the TBAC on my LWRC piston gun and it's shooting fine. I have an H2 buffer and Tubb's Flatwire SS Spring. Ejecting about 1:30-2:00 so I might need a little more tuning.
For what it's worth,
Ive noticed that whether it's a DI or a piston gun, when suppressed, they both run god aweful dirty.
All the crap that's flowing back into the rifle is traveling down the bore, not the gas tube.
Ive noticed that whether it's a DI or a piston gun, when suppressed, they both run god aweful dirty.
All the crap that's flowing back into the rifle is traveling down the bore, not the gas tube.
My SCAR runs cleaner suppressed than my ARs, but still dirtier. It also has a two-position gas system for suppressed and regular fire, which does help. An adjustable gas block on a DI AR compensates for an improper/oversized barrel gas port, not so much suppressed fire UNLESS you are actively changing the settings when you stick your suppressor on.
Agreed to some degree, maybe because my suppressor is a 30 cal there is more clearance for the gas to escape out the end of the barrel (suppressor).
I don't notice it much on the piston gun. Shooting groups with different hand loads and coyote ammo it didn't even come to my attention. The BCG was pretty clean looking but I only shot about 30 rounds.
Im not really concerned about dirt........but function...is the piston inherently better with a can?
From what I have seen on my suppressed weapons ( 30 cal all subs) it is 6 one way half a dozen the other. Now full auto fire ( suppressed) with a DI can be painful on the eyes, the gas can be overwhelming at times, the piston does help alleviate that some. YMMV
There are other functional concerns with pistons before suppressed operation.
I have a 16" HK556MA1 (416 clone) and a Primary Weapons System Mk109 SBR (10.5", .300 BO), both pistons, neither has an adjustable gas block and run suppressed just fine.
Can you elaborate? Interested in all aspects of my tools.
By no means an expert, but DI fans always point out carrier tilt as a big issue in piston guns. There's literature on the topic, but I think when most people talk about why pistons suck they are specifically talking about the AR-15 adapted to some kind of piston operating system vs. an actual piston gun a la AKs, SCARs, etc.
that's the answer I was looking for. Im going to buy a hk556MA1 and use a can full time. 3 grand is alot but I paid that for my GAP-10.
You are looking at it the wrong way. Piston guns and especially AR, the MR556 included, are louder with suppressors than a proper DI setup. They are also harder on the bolt and cam pin. This is because not only is more KE being transfered into them from the op-rod, but there is no delayed unlocking of the chamber. The chamber unlocks at much higher pressures which means more noise to the shooter, and more stress on the bolt/cam pin.
A DI setup with a Superlative Arms AGB is far superior, and you can make it even better by adding an LMT Enhanced carrier (I'd go for the whole BCG) and something like a Griffin Armament SNACH CH. Not only that, but the DI will be cheaper and use better parts, so you end up with a nicer, more accurate, more reliable, and quieter rifle for the money.
I honestly have no idea why anyone wastes their money on piston ARs outside of those who think they will be doing over the beach stuff.
A DI setup with a Superlative Arms AGB is far superior, and you can make it even better by adding an LMT Enhanced carrier (I'd go for the whole BCG) and something like a Griffin Armament SNACH CH. Not only that, but the DI will be cheaper and use better parts, so you end up with a nicer, more accurate, more reliable, and quieter rifle for the money.
I honestly have no idea why anyone wastes their money on piston ARs outside of those who think they will be doing over the beach stuff.
great info thanks!
* Edit: To OP, the piston sysems are proprietary and if not designed to be adjusted then there are other ways to tune it to run suppressed as I explain below.
I run both DI and Piston suppressed.
I changed my LMT MRP CQB Piston AR buffer to a slash H2 and Tub flatwire. It completely changed the felt recoil pulse to that of a properly tuned DI. My experience is that it does run much cleaner than my DI's both suppressed and unsupressed with no gas in my face.
The DI's have SLR adjustable gas blocks, JP matched bolts, various carriers with either JP H2 silent capture springs or Tub flat wire springs. They run about the same suppressed as unsupressed.
In the end it is personal preference DI vs Piston. Valid points for choosing one over the other but in the end it's up to the buyer. The Piston issues from years ago have by in large been resolved.
Suppressor is a Rugged Surge.
I run both DI and Piston suppressed.
I changed my LMT MRP CQB Piston AR buffer to a slash H2 and Tub flatwire. It completely changed the felt recoil pulse to that of a properly tuned DI. My experience is that it does run much cleaner than my DI's both suppressed and unsupressed with no gas in my face.
The DI's have SLR adjustable gas blocks, JP matched bolts, various carriers with either JP H2 silent capture springs or Tub flat wire springs. They run about the same suppressed as unsupressed.
In the end it is personal preference DI vs Piston. Valid points for choosing one over the other but in the end it's up to the buyer. The Piston issues from years ago have by in large been resolved.
Suppressor is a Rugged Surge.
Last edited:
While it is a fact that adding a suppressor causes over-gassing, many piston systems have different settings for running surpressed or not surpressed.
OFG
The reality is that the suppressor does not and cannot increase the back pressure so its not responsible for most of the ills attributed to it. Pressure drops as the bullet goes down the bore and the bullet passes the gasport at the same place and time whether there is a can installed or not. For that reason the gas pressure is the same with or without a can. Doesn't matter if its piston or DI. So in real life the idea that the bolt opens sooner or the cam pin gets hammered more is crap.
What is true is that the residual pressure in the bore is higher with the suppressor installed because it acts like an accumulator and increases the time for the pressure to drop. This can change the way things go when the bolt opens like dumping more crap in the receiver as gas blows by the cartridge case, speeding up the bolt by pushing the extracting cartridge and bolt back faster and keeping more heat in the system so that the barrel and gas system get hotter quicker. There may be some difference in what you see between DI and piston but in both cases the main effect is created by the cartridge case itself being used as a piston and not by the gas system. Once the bolt has unlocked the gas system can't really do anything else as in the DI system excess gas gets blown out the bolt carrier with no effect on the bolt and in a piston system the excess gas gets blown out dump ports.
The systems with adjustments for gasport size reduce the initial pressure into the system and depend on the increased amount of time under pressure that the suppressor helps create. It allows the same amount of energy to operate the bolt but can do nothing about the residual pressure in the bore. That still causes extra blowby from the ejection port and increased bolt speed through cartridge case pushing.....
Frank
What is true is that the residual pressure in the bore is higher with the suppressor installed because it acts like an accumulator and increases the time for the pressure to drop. This can change the way things go when the bolt opens like dumping more crap in the receiver as gas blows by the cartridge case, speeding up the bolt by pushing the extracting cartridge and bolt back faster and keeping more heat in the system so that the barrel and gas system get hotter quicker. There may be some difference in what you see between DI and piston but in both cases the main effect is created by the cartridge case itself being used as a piston and not by the gas system. Once the bolt has unlocked the gas system can't really do anything else as in the DI system excess gas gets blown out the bolt carrier with no effect on the bolt and in a piston system the excess gas gets blown out dump ports.
The systems with adjustments for gasport size reduce the initial pressure into the system and depend on the increased amount of time under pressure that the suppressor helps create. It allows the same amount of energy to operate the bolt but can do nothing about the residual pressure in the bore. That still causes extra blowby from the ejection port and increased bolt speed through cartridge case pushing.....
Frank
Interesting. So if the gas pressure is the same, why does my Adams Arms piston upper only cycle on the "surpressed" setting with the suppressor but not w/o the suppressor?
The explanation I've heard is that the suppressor increases the dwell time, thus it may not drastically increases the peak pressure, but it definitely does increase the time duration that the pressure lasts.
Force =Pressure x Area
Impulse = Change in Momenum = F x time
Even if peak force does not change, the impulse imparted on the piston/op rod/gas key etc definitely will.
Force =Pressure x Area
Impulse = Change in Momenum = F x time
Even if peak force does not change, the impulse imparted on the piston/op rod/gas key etc definitely will.
Last edited:
Yup, Benito is right. Pistons are harder on bolts and cam pins and extractors as there is less delay in the unlock so it uncorks as higher pressure. Not to mention there is actually more KE in the system due to the oprod. As another user posted, you generally need a stronger spring and buffer in a piston. No on runs them in competition for the reason (and others), in DI you can have a much lighter operating system that needs way less gas/KE to operate. Suppressors only exacerbate this and it means it is louder at the gas port for pistons. You can get a good tuned piston system performing similarly to a DI, but never exceeding it and it will always be a bit louder and harder on internals. And you pay more for the pleasure.
This doesn't mean pistons are BAD just sub optimal and expensive.
This doesn't mean pistons are BAD just sub optimal and expensive.
