Gas piston Vs Direct Impingement?

[SR420]

All of the DI ARs I've owned over the past few decades have been 100% reliable.

I switched to a piston driven AR only after adding a suppressor to my tool box.
The AR I chose was designed with a piston system from the ground up, not a kit.

[BPowderkeg]

very interesting !

I have put more than 10,000 rounds through my (DI) AR in the past 3 months without a failure... That means that in total that gun has upwards of 15,000 trouble free rounds through it.

how many cleanings ?

[BPowderkeg]

...not Judging, another Great thing about Gun forums

whoa.......!! you apparently have not been around gun forums much, i have been around internet gun forums for over 20 years and have found them to be very judgmental, hypocritical, dishonest, plus many other negative terms !!

enjoy.., but beware !!

[allaroundhunter]

Originally Posted by BPowderkeg

very interesting !



how many cleanings ?

I have cleaned it about 5 times in the span that I have fired 10,000 rounds (solid cleanings). I have wiped the bolt down and given it some CLP about every 750 rounds.

.... And my barrel is getting pretty worn out as of late

[CharlieDeltaJuliet]

Here is an article that is a good read about the Hk.

UBL was killed with an op rod gun. What do you send "When you only care to send the very best"? - Dev Group (Or Delta or 24th STS, or Ground Branch, FBI HRT, TSA, etc) with HK416's. Built from he ground up to be the most reliable, combat rifle. While its competition in dependability would be the AK, it beats it hand down in accuracy. Heck even the California Swat that responded to the Santa Monica shooting were all decked out in them. It's not to spend more money, I assure you they choose them because they want the very best when their lives are on the line. Now I am not talking of Adams piston kits or any other that was designed to fit into a DI gun, but only about Hk. If I get on LWRC it would be even more long winded.. And I am tired..lol


http://soldiersystems.net/2013/03/30...tiring-my-416/

[Striker1]

Here is an article that is a good read about the Hk.

UBL was killed with an op rod gun. What do you send "When you only care to send the very best"? - Dev Group (Or Delta or 24th STS, or Ground Branch, FBI HRT, TSA, etc) with HK416's. Built from he ground up to be the most reliable, combat rifle. While its competition in dependability would be the AK, it beats it hand down in accuracy. Heck even the California Swat that responded to the Santa Monica shooting were all decked out in them. It's not to spend more money, I assure you they choose them because they want the very best when their lives are on the line. Now I am not talking of Adams piston kits or any other that was designed to fit into a DI gun, but only about Hk. If I get on LWRC it would be even more long winded.. And I am tired..lol

I'll bet more bad guys have been put down with DI guns...just sayin'

[CharlieDeltaJuliet]

Given, and I guarantee the AK has the DI AR beat for that too, but considering the Hk has only been in operation for a few years.. We might have to wait and see. Don't forget the marines are getting the IAR M27...

[ThatBeardedGuy]

Also don't forget that the USMC watches Army weapons competitions closely, and piston-drive is not a requirement for the current round of contestants, IIRC.

[CharlieDeltaJuliet]

The M27 (modified 416) has already been chosen to replace about half of the M249's. When the government has hundreds of millions in the M4 and all of their replacement parts, I would not expect them to replace with something else. As I said before it isn't for everyone. IIRC the cost of a complete 416 to the government is $1100 which is almost 2x the cost of an M4( link to the m4 cost per rifle http://www.fas.org/man/dod-101/sys/land/m16.htm).That does not mean the 416 isn't superior. I trust Delta,and the SEALs, when they say it is a vast improvement and their weapons of choice. They are the best of the very best, and know what they need to do their job. They just don't have the budget woes an average soldie does.

[CharlieDeltaJuliet]

I am done with the argument, because that is what it has became. I was supplying facts and my experiences for the OP. I am not even going to check the thread because I am not trying to change anyone's minds. I am simply providing the piston side of the answer. I think myself and the few others that have shot and own the Hk or LWRC.. Can attest to the quality of the gun. I never pretended to know how your AR's run. All I can say is how mine runs. I also provided facts from tests, Hk, and one of the co-creators of the hk416 Larry Vickers.. Take care

CDJ

[Bartholomew Roberts]

Originally Posted by CharlieDeltaJuliet

That is why I precisely would not defend the Ruger as said earlier, I have no experience with them. The Hk is a considerable difference in temperature.

If that is in fact true (I haven't seen any data on it, so I would not know), I doubt the operating system is a major contributor to the difference. For example, the POF piston system runs much cooler than the DI; but it also uses a giant finned barrel nut that provides much of the cooling.

I believe the piston system will last longer due to les heat transfer and fouling. The wear is less. The standard usage life of an M4 before re barreling and bolt etc.. from the government is 8-10k rounds. The 416 is almost 4x that.

I guess I am missing how the operating system causes one rifle to have to be rebarrelled faster than a different rifle with a different operating system? Could you elaborate on that?

As to the bolt, the AR15 bolt is designed to be used in a 20" rifle under certain operating parameters. It was designed using 1960s metallurgy. We know that we can greatly enhance the life of the bolt simply by radiusing the lugs where they meet the bolt or by using higher quality metals like 9310 (or both). However, changing the bolt design means changing the barrel extension and tracking that part in existing inventories, so it won't happen. Changing the metal is an easier solution; but you have to overcome institutional inertia. The Knight's E3 bolt has run 20,000 rounds.

Frankly, I'll be interested to see how the HK416 survives in the military small arms maintenance system (which is the root of many of the current AR15 problems) and if it turns out to be as durable as the M16 once it gets treated like one on a consistent basis for 20 years. For that matter I'll bet you could shoot 4 M16s to death before you ever got one 416 back from H&K's service department. However, the HK416 isn't limited by the design of its bolt, barrel extension or metallurgy. The engineers were free to use what they could without having to worry about compatibility with the 20" M16 (except for magazines - and even that is arguable).

None of that has anything to do with the operating system though.

Also not buying the "But the SEALs and Delta use it!" argument. I know a SEAL who carried an M14 for years. He didn't like it better than the M16 or think it was a better rifle; he carried it because he did a lot of over-the-beach stuff and in that specific environment, the M14 was a better choice. And contrary to popular perception, he didn't have a Matrix-style arms room to choose from.

[Quentin2]

To me, the worst potential problems of the various piston AR designs are parts availability and quick repairs, especially over the long run. If your DI AR needs a part you have your choice of hundreds of vendors selling standard parts, and you can install them yourself or have a local gunsmith do it. If your Ruger piston AR (for example) breaks, you must get parts from Ruger, and they may not provide them to you - you likely will be told to send the rifle to them or an authorized service center, not you or your local gunsmith. And if a proprietary piston design is ever orphaned, well you'd better start scrounging for parts now...

And with so many piston designs out there it's fair to assume a shakeout of some kind where some designs will be abandoned. You could be stuck with Beta vs. VHS or HD-DVD vs. Blu-ray.

[Quentin2]

I see the advantages of Direct gas impingement as:

Lower cost, lower weight, standard parts available from multiple sources, simple, proven design that works well in many applications and with standard carbine and rifle length barrels


Piston designs, as has been pointed out earlier, may be better suited for certain tasks and AR designs but they aren't superior for the vast majority of AR applications.

[buckhorn_cortez]

Dang it Buckhorn_Cortez, I am dying to get my hands on the Barrett. I bet it is creaking sweet. Heard great things about them.

It is a nice rifle. Ronnie Barrett knows how to design rifles. I had a Colt AR in 1984 and it was a jamtastic machine because it did not have the M4 modifcations. I sold it in 1985 and didn't think about an AR until 2010.

Then I shot a friend's SIG, and started looking at piston ARs just to see what they were all about. I looked at and shot as many as I could, including SIG and HK. Then I saw a REC7.

It's hard to explain without seeing, handling, and operating the rifle. It is so well designed and manufactured. The fit and finish are like a Wilson - while the design and operation are totally Barrett. It works under all conditions with no extra help needed.

I cleaned it at 3,000 rounds to see what was going on with it. The barrel was fairly dirty and needed cleaning, but the bolt and inside of the receiver were nearly as clean as when it was new. I took the gas piston assembly apart (you flip a lever on the front of the gas block, tilt the gun barrel down and it falls out of the gas block).

I wiped the piston and inside of the gas block with SLIP Carbon Killer and the cleaning rag was faintly grey. After that, I became a believer that the piston system truly is self-cleaning.

The gun needs minimal lubrication as the bolt and carrier are NP3 coated. I have been using a very light coating of ProGold MFR-7. It's very nice to run the gun almost dry where I live (New Mexico) without needing to constantly lubricate the bolt. It never has a bolt covered in a mixture of gun gas/fouling munge + dust + oil .

It is farily accurate as it will give slightly under 1 MOA accuracy running 55 grain bullets at 100 yards. The gun club I belong to has a 100 yard tunnel so you can test rifles without wind drift. I've done that with the REC7 on two ocassions with my sled and sand bags - and both times it shot 0.75 MOA.

It seems to be the rifle no one knows about (or thinks about) as I have never seen another one (although the FFL I purchased it from says he sells about 1-2 per week). I would recommend looking at the REC7 if you can find one. It is certainly one of the better options in piston operated ARs.

[Bartholomew Roberts]

In somewhat related news, the Army just cancelled the Improved Carbine program saying none of the submitted rifles met the minimum criteria for continuation. The contenders were FN FNAC (SCAR), HK 416A5, ACR, ADCOR Bear, Beretta ARX160 and Colt Enhanced M4. All contenders were piston designs.

The Army wanted to see 3,600 mean rounds between stoppage with M855A1. According to Army data, the current M4 does 1,691 MRBS with M855A1.

[BPowderkeg]

The contenders were FN FNAC (SCAR), HK 416A5, ACR, ADCOR Bear, Beretta ARX160 and Colt Enhanced M4. All contenders were piston designs.

they should have tried the LWRCI M6 originally designed by P. Leitner-Wise and a proven piston carbine, i have one of the originals and it functions flawlessly, is "man sized target" accurate to over 500 yds., it does have one flaw and that is the flat coil op rod return spring, when they break the gun still functions, just ask me, mine has broken two of them.

[robertsig]

this type of arrangement is not such a bad idea for military rifles but it's horrible for civilian application as a piston requires a very specific amount of pressure from the fired projectile to actuate it. ......

if the pressure is too far out of spec your piston will no operate and you will effectively have a bolt action AR15 requiring you to operate the bolt manually.

Baloney. Tell that to my PWS MK116.

[ThatBeardedGuy]

they should have tried the LWRCI M6 originally designed by P. Leitner-Wise and a proven piston carbine, i have one of the originals and it functions flawlessly, is "man sized target" accurate to over 500 yds., it does have one flaw and that is the flat coil op rod return spring, when they break the gun still functions, just ask me, mine has broken two of them.

Our rifles now are more than man-sized accurate to 500 yds. If your weapon has a known flaw, no matter how minor, the military probably won't be interested in it.

[Bartholomew Roberts]

they should have tried the LWRCI M6

The LWRC was submitted for Phase I of the competition but LWRC and a dozen other manufacturers pulled their entries because the Army wanted all rights to the TDP prior to advancing to phase 2. I bet those companies are glad they declined right about now.

[jehu]

Don't forget that the most widley used battle rifle in history,AK47, is a piston gun. I predict that one day soon DI will become obsolete when the piston operating system is perfected in the AR platform. I have two LWRC SPR's and 5 DI's.

[BPowderkeg]

allaroundhunter, what is the maker of your piston gun ?

[BPowderkeg]

everyone !
i have tried to find the specifics of every piston operating systems of every AR-15/M4 design and the only one i can find the specs on is this one,



not a very good view, but this design is in my OPINION one of the best piston systems yet !

all these piston makers that advertise in gun magazines tout their system but very few show their specific design, even when i go to their web site they do not show it specific parts LWRCI has a slide show of how theirs work.

[Quentin2]

Don't forget that the most widley used battle rifle in history,AK47, is a piston gun. I predict that one day soon DI will become obsolete when the piston operating system is perfected in the AR platform. I have two LWRC SPR's and 5 DI's.

"One day soon" ... You sure about that?

[Boomer58cal]

I don't get the range commando's. 10,000rds at the range is not the same as 10,000 rds in jungle nee deep in mud combat. In combat you don't just clean your gun every so many rounds. You clean it when you get a chance. You can't compare shooting the two under perfict conditions. Both DI and piston work great under those conditions. Piston gun works better in he!!.


My 0.02 Boomer

[SR420]