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Old June 13, 2013, 06:19 PM   #26
CharlieDeltaJuliet
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It isn't because of cleaning. It is because of less wear and less lube needed to run them. This is why "this method virtually eliminates malfunctions common to direct impingement gas systems since hot carbon fouling and waste gases do not enter the receiver area. The rifle stays cleaner, reducing heat transfer to the bolt and bolt carrier, and drastically reducing wear and tear on other critical components. The service life of all parts is increased substantially"

That is from their brochure. I have fired the 416, ran 3-30 rounders through it and was handed the bolt. It was not hot nor even remotely warm. When they ran over 20,000 rounds (full auto in one weekend) through a 416 without a hiccup. It still was shooting well within military accuracy specs... The life span of the rifle is 3-4 times the standard M4. They are more forgiving in sand water and dirt. That is why the Navy seals use them. That is why the marines are replacing part of the M249's with them...
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Old June 13, 2013, 06:30 PM   #27
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DI is fine for civilian use.

OR

If you were crawling around the jungle, dragging it through rice paddies for months at a time it works great for the military also.
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Old June 13, 2013, 06:38 PM   #28
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If you search either TFL or the Internet, there are many good discussions on this. Most of the actual differences due to operating systems are overblown - for example, the 416 has a longer life because it is a modern firearm designed with modern materials as opposed to a modern carbine made from parts originally designed for a 20" rifle in 1960.

If you look at comparable rifles with a DI operating system (Knights Armament SR15E3 for example); but modern engineering and materials, they compare very well.

For example, there is a comparison between a Ruger SR556 piston and a Colt DI to evaluate the hot bolt issue. It comes down to a 40F difference after 5 consecutive mag dumps. It strikes me as unlikely that kind of difference is likely to have a functional effect.

Personally, I would go with a DI system (and the old 1960s parts) because the parts are plentiful, available, interchangeable, and there is a MASSIVE knowledge base on their operation. As much as I sometimes get interested in a new SR15 or a fancy piston - expensive proprietary parts do not excite me (although you can now get AR bolts in 9310 steel).
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Old June 13, 2013, 07:15 PM   #29
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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.
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Old June 13, 2013, 07:23 PM   #30
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I can't think of any instance where I'd need to fire a magazine and then pull the BCG, so that smacks of a gimmick to me.

I've literally never had an issue with DI-gassed weapons that wasn't related to a spring failure in the magazine. They simply don't cause issues for me.
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Old June 13, 2013, 07:51 PM   #31
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See, I am going to have to disagree there tahunua001. I will put my Hk against any DI gun for reliability. I promise eight out of ten times you will have to clean yours first. As far as specific pressures, the Hk has a self regulating gas block. It has never failed to fire any round, including low powder sub sonic loads or any hand load I have used. While reliability may be an issue for some piston manufactures or piston conversions, an LWRC or Hk are very reliable, I will even say more so under certain conditions.
ok first of all, you are comparing a $3000+ H&K to a $1000 DPMS project rifle. that's like challenging a turbo'd Jetta to a race when you drive a Lamborgini Diablo.

secondly, I mentioned that Piston ARs do not foul as quickly as DI, so your assertion of being more reliable because I'll have to clean first just goes on to re-enforce my statement. however, give me a cleaning kit and I can keep my AR going just as long as you can keep yours(within reason).
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Old June 13, 2013, 07:58 PM   #32
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No tahunua001, I wasn't comparing to a DPMS, I will compare it to my DDV4. I disagree, 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 will be the first to say, most people will never shoot an AR enough to tell the difference. The piston guns are a waste for most to spend the price of the Hk or LWRC. I just think IMHO from my experience with them, they are superior in almost every way except price.

Sorry tahunua001, I mean no disrespect, this is just my opinion.
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Old June 13, 2013, 07:59 PM   #33
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If I'm ever in a place where I have to shoot so many rounds that I'm literally required to stop and clean the weapon to keep firing, I should probably reconsider my life choices.
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Old June 13, 2013, 08:03 PM   #34
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Anywhere there is fine sand. It isn't even about rounds fired its about dependability in multiple conditions, and overall life span. The piston system handles sand, water or mud. I am not arguing semantics. I am stating my experiences with the two systems. I own 4 DI guns and love them. One of the is the most accurate AR I have ever owned(24" barrel). But I won't deny the piston system is better, if Hk, or LWRC.
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Old June 13, 2013, 08:06 PM   #35
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If you've got $3000 to drop on a rifle whose performance differences only start once you've fired about $20,000 of ammo through it, more power to you.

I've been in the military for six years and owned ARs for four and I haven't even come close to shooting that many rounds.
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Old June 13, 2013, 08:06 PM   #36
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Enough arguing, we each have our own opinion. I will stand by mine, you stand by yours and we will agree to disagree. I just tried to do the same as you and give the OP my experience with gas piston guns..
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Old June 13, 2013, 08:09 PM   #37
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And yeah, I've spent a little time in places with "fine sand". Granted, I wasn't doing any shooting, but it's not really hard to keep an M4 clean enough to fire.

I've run my ARs wet, bone-dry, and everywhere in between. Both were basic M&Ps. I can't make them stop working.

Sure, the piston system is probably a better gas system. But going off Tahunua's analogy, a Lambo is going to beat a Mustang all day long, but at the end of the day, my Mustang gets me to work and back just fine.
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Old June 13, 2013, 08:10 PM   #38
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No tahunua001, I wasn't comparing to a DPMS
hmm... kindof sounds like you were.
Quote:
I promise eight out of ten times you will have to clean yours first.
HK is also an exception to the rule. DD, AA, Ruger, Stag, all of the common suspects do not have self regulating gas systems and suffer greatly for it.

also, Milspec ARs are not the best in the first place. HK is quite possibly the highest quality mass produced AR on the market... a DPMS/Bushmaster/Remington M4 is not going to be in the same ball park. I wonder if you were to compare your HK to a Seekins precision or Larue tactical if the fight would be so one sided?

EDIT: I also added the modifyer, within reason. shooting 1000 rounds in 20 minutes is not what I would call reasonable use. I'm talking about 1 slow mag dump(say 2 seconds per shot) every 10 minutes or so.
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Old June 13, 2013, 08:11 PM   #39
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I'm not arguing. I'm pointing out for the benefit of all that DI is not the boogeyman of gas systems. It's really easy for everyone to form an opinion on this debate, and I really wish I could find the article where a former SF guy ran thousands of rounds through a bone-dry DI-gassed AR with no issues.
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Old June 13, 2013, 08:13 PM   #40
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Nothing wrong with an M&P, I own one and love it. I have seen a DD quit running, while a group was testing against a LWRC. The LWRC didn't cease, but they tortured them both the same. It took over 4k rounds dry with dirt and sand but, as I was saying I am not knocking your guns at all. Take no offense. I stated my experience with the two systems.
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Old June 13, 2013, 08:14 PM   #41
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I agree 100% tahunua001. But I still think the Hk can hold its own.... I agree though about mil-spec.


And TheBeardedGuy, I never said they were the boogeyman. They (DI guns) honestly are more dependable than most will ever need. I believe you about the SF guy. I have seen a Colt go over 50k rounds on all original equipment. There was a big write up about it. I shoot my DI guns as much as my Hk. It the past 12 years or so I have put over 25k rounds through AR's. I have around 4k through my Hk (ammo went up too much to replace as easy). As I was saying I just believe the Hk and LWRC are better AR's than DI AR's. Just my opinion.
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Old June 13, 2013, 08:17 PM   #42
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I own both types. A Barrett REC7 (piston) and a Les Baer (DI).

The Barrett was designed as a piston gun and not a DI retro-fitted to be a piston system - I think that's an important point. The rifle was designed and built to be piston operated. The REC7 gas block/piston is self-cleaning, self-regulating and will shoot whatever level ammunition you put in it, if you run a supressor the gas block has a position to regulate the gas for the supressor. The piston system adds 3.8 oz weight to the rifle.

Buy whichever you can afford. You're probably safer buying a DI as you can find one that will work reliably for whatever price point fits your budget. Piston rifles are more expensive and you have to carefully look at them for design, operation, and features.
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Old June 13, 2013, 08:21 PM   #43
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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.
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Old June 13, 2013, 08:28 PM   #44
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Hi, Sam Colt,

I did not mean that gas piston system in general was not developed, I meant that the AR-18 was not a fully developed rifle. Its folding stock was not well designed and was a weakness, plus the failure to capture the bolt springs on the guide rods when the rifle was disassembled was not a good design; a direct copy of the M3A1 system would have been better. The AR-18 is easier to field strip and clean than the AR-15, and it has no spring in the butt stock to collect water or moisture. In addition, its guide rod bolt system, as opposed to the tight bolt and bolt carrier fit of the AR-15, allows plenty of room for dirt and gunk that would otherwise stop the rifle.

Overall, the rifle, I thought, was better than the AR-15, not only because of the piston system but because of the economy of manufacture and consequent cost savings. It could also be made in countries with a less developed manufacturing base, a benefit for U.S. allies who could manufacture their own rifles rather than having the U.S. supply them at a grand a pop.

Jim
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Old June 13, 2013, 08:30 PM   #45
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I'm sure the HK is a better AR than just about any AR I could reasonably see myself paying money for. I absolutely believe you when you say that HK makes a good AR. Of course they do. The Germans rarely ever misstep when it comes to firearms.

But again, when you consider price points, the HK is to ARs what Wilson Combat is to 1911s. It's the high-end, and I'd feel bad about abusing such an expensive rifle.

That being said, my next purchase will be a Tavor SAR 16.5" so I'm going piston-driven after all, in a way.
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Old June 13, 2013, 09:16 PM   #46
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You will enjoy the Tavor. It is a hell of a rifle. Enjoy..

CDJ
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Old June 13, 2013, 09:57 PM   #47
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I have shot a HK MR556 (civi 416) and the Tavor next to my BCM HSP Jack Carbine... I still prefer my Jack.. and as my name will say... I am an HK fan boy.

Piston costs too much for what you really get out of it...which the only benefit is an extra 3 mins of your less that would usually be spent cleaning your DI system. Sorry but that's about it. They run cleaner.. but not as clean as some people make them out to believe. Also if you throw a suppressor on the gun.. it will run just as dirty as a DI system because the bolt will be unlocking while the can is still under pressure so you will get blow back down the barrel not just a gas tube.

The late great Noveske himself explained this in an older interview of why they toyed around with, but never felt the need to make a piston AR.

Buy what you like, but a piston isn't any more reliable than a DI.. just saves you some time cleaning.. if your time is worth the price difference.. or you just LIKE that particular AR... more power to you.

Have a pic of the Jack and the Tavor.... not the Hk however....



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Old June 13, 2013, 11:20 PM   #48
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Then there's the Daewoo K2 and derivatives. This is the rifle used by the South Korean Army. Many features, such as the bolt carrier group, are derived from the M16 and the gun uses the M16 magazines. However, it has a gas piston system derived from the AKs. It is somewhat similar in appearance to the AR18.

I bought the civilian version (AR-100) one back before they were banned in 1994. I haven't put a lot of rounds through it but I've never had any issues with it. The folding stock is pretty cool. http://en.wikipedia.org/wiki/Daewoo_..._Industries_K2
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Old June 14, 2013, 06:24 AM   #49
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I will leave you with this... and will let this horse die...


Larry Vickers said the following on M4C.net:
"Piston AR's have their place- to determine if you need one ask yourself four questions;

1) Do I need a barrel length shorter than 14.5 inches
2) Do I need to run my gun suppressed a lot
3) Do I need to shoot a lot of full auto
4) Do I need to shoot a wide variety of ammo

Piston guns have been shown to be superior in those four categories over a DI gun. If you can say no to all four questions a good DI gun will do you fine.
http://www.m4carbine.net/showthread.php?t=107613
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Old June 14, 2013, 07:44 AM   #50
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Here's my take on the gas impingement vs. gas piston debate as it pertains to AR's. The AR was designed around gas impingement - it's a good design. Compact, lightweight, efficient design. It works well. Redesigning the AR to be gas piston is making it into something it was never intended to be. I have absolutely no interest in gas piston AR's and avoid them like the plague!

That doesn't mean I dislike all gas piston 5.56 rifles - there are some excelent ones out there. If I want a gas piston rifle, I would choose one that is not AR based and was designed from the start to work with a piston.
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