Riddle me this Batman

jo6pak, I'm all for improvements--when they do indeed improve.

But in testing between DI and piston, I'd start with a couple of questions:

1. In combat, what's generally the maximum number of rounds fired before an opportunity to clean the weapon occurs?

2. What is the most common length of time between opportunities to clean the weapon?

IOW, the overall heavy-usage parameters.

Seems to me that #1 gives a minimum baseline for reliability. Gotta make it through a worst-case firefight. An assumption here is that a cleaned weapon will continue to function.

#2 gives an idea of field conditions to be dealt with--weather and such. A firefight ends and there's return to base where the Sgt sez to unload a truck and then maybe there's some time to eat before going on guard duty and then take care of some other chore. And in the meantime it rains.

Just arbitrary: Say a guy burns a thousand rounds and it's several days before he has time to clean the weapon. Then away he goes again, all clean and happy. If there aren't jamming problems with that sort of usage, what's to improve?
 
And you are behind the times a bit, Colt dropped the CM901 from the competition.
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Thanks BR and Fish for posting the news link. BR, are you sure they didn't pull it because they realized it was going up against 3 DI rifles and Colt is just spinning a yarn?

So with this latest news, (Not really new, as I don't follow the developments that closely and the article is from late November of 2011.) it appears 100% of the participants have chosen to submit a piston rifle in the competition. Colt pulled a switcheroo and pulled out their DI gun in favor of a piston gun!

That should just about seal it, doesn't it? Remember, we're playing nice this time.
 
This is the way I see it but if I'm incorrect, please make corrections...
HKGuns said:
That should just about seal it, doesn't it?
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I don't think so. The current issued rifle is still the Colt's own DI (their "ace in the hole?") so technically Colt is competing against their own rifle if you wish to view it that way. Furthermore, "winning" does not guarantee a replacement.
 
HKGuns said:
That should just about seal it, doesn't it? Remember, we're playing nice this time.
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I'm not interested in playing nice. I would prefer to have an adult discussion about the topic; but for that to happen, you would first have to understand:

A) That I find your basic premise on how we can determine the superiority of operating systems to be invalid

B) Then you would need to re-read my previous post, understand it, discern a least a few of the reasons I find your premise invalid and compose a post that addresses those concerns.

All you've done here is restate the same premise I have a problem with and added information that I already knew. Clearly, you either don't understand what I wrote or you understood and you want to be a smart-ass? Which is it?

bpeezer said:
How hot will the barrel get in the piston gun?
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Heat in different AR variants differs depending on the variant you are comparing. Changes in the receiver/barrel nut design that aren't all that obvious to the naked eye can have a much bigger effect than the gas system.
 
And anyway, aren't these trials more like annual reviews? No promise of change but rather to see how the current issue stacks up against the newer kits? Then from there, making a decision on whether the the differences are enough to warrant the effort? If I'm just repeating someone, I apologize.

To be clear, I currently own an M6-S from LWRC and have owned a Bushmaster. I say "owned" because I gifted it to my Step-Father shortly after getting the M6. The Bushy was great, it was just that he didn't have an AR and wanted one more than I needed mine. Honestly, I can't know which one is more reliable because owning a LWRC is a luxury and not a necessity and I can't foresee placing my rifle through anything close to the conditions our men and women serving have done and will do.

In any case, I have a sneaky suspicion that one advantage(?) a well engineered piston has over DI is possibly a maintenance issue on the user's part i.e., "lack of". A lazy man's AR? Maybe. I'm referring to shooting hundreds of rounds or more, depending on how heavy your foot is and then putting it away for extended periods of time, allowing the carbon build-up to harden, then "wash, rinse, repeat". Maybe. Now, seeing as how a professional soldier would not/could not do this, that advantage(?) is null and void. Far-fetched possibilty?
 
In combat, what's generally the maximum number of rounds fired before an opportunity to clean the weapon occurs?
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Sometimes it can be quite a length of time, all night and into the morning. You don't have to clean it, just squirt a dab of LSA on the bolt, it'll keep going.

That's why you see those little plastic bottles of LSA in the camo band on the helments.

I've poured water on a '60 to keep it going, only time I burned on up was because I ran out of water (and couldn't pee).
 
matter of choice.....or is it time?

I think it is a proven fact that if the chamber/bolt is kept clean on a DI firearm, that it works as advertised. The heat may be an issue........but all you are changing is the location of that heat.....either at the chamber or the fore end. Given the number of rounds that your average sheep dog puts down range and most, I hope, would clean their weapon after a day at the range; whether it is a DI or a piston is a non issue. DI weapons have gone to war 6 times (Viet Nam, Grenada, Panama, Iraq x2 and Afghanistan), last I checked they were still good to go. Is it time to update/upgrade/change a design that is over 50 years old? I would hope so with the plethora of new metallurgy, propellants, etc.. Things change, the battle field has changed, hence the tool of the infantryman must meet the challenge of the environment when and where ever that might be.
 
BR said:
Didn't we just have this discussion? As I recall, I pointed out that the heat difference at the bolt of an M4 was something like 30-50 degrees hotter, with the peak M4 temperature being around 175F after 5 mags.

Maybe someone could advance a theory that explains how that 30-50 degree difference in temperature has an effect on function? Maybe they'll even get crazy and explain to me how lube that doesn't dry off at 145F is drying off at 175F when the flash point of that lube (CLP) is 270F? I keep looking for it in these links to various news stories; but usually I just see the allegation with no facts supporting that diagnosis.
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It's very difficult to win a internet argument by stating the facts.:rolleyes:
 
They run cooler and don't get as dirty as fast.
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There's the rub, it's not established fact, it's just opinion. Those two factors are not mandatory in the operation of the gun.

Art asked about the worst case scenario, and it's been addressed more than once: Soldiers clean their weapons daily, more if in the field. Humping a thousand extra rounds doesn't happen. The imaginary worst case situation is just that, a hypothetical what-if? to keep an argument rolling along.

The use of the M16/M4 is tested with full auto fire to simulate what the Army thinks is a worse case situation. After 45 years, the results apparently haven't been significantly poor enough to buy into another weapons design. If anything, we've stuck to it precisely because it offers advantages that keep being ignored by piston fans.

Pistons actually don't do much of anything better -
Most of the designs are a retrograde adaption to a gun meant to eliminate the operating rod -

Why put one back into the design when all the work was done to eliminate it?

Because some shooters can't and won't accept that a M16 gets a dirty bolt carrier? At least it's much easier to get to, which is exactly the advantage you need since the user has to maintain it daily anyway. Garands and the M14 with pistons on the barrel were the PROBLEM, it was hard to service and became an issue to improve. The M16 fixed the issue. It's not hard to maintain one.

If pistons or DI work equally well, there's no financial reason to change. Keep what the system already supports without wasting taxpayer money changing to something with no advantage. NEWSFLASH: That's exactly what SOCOM finally decided - that's the significance of the most highly trained and professionally accomplished warriors in the Armed Forces experienced, recorded, and the implemented. The SCAR 16 gave them no advantage, end of wasting tax dollars.

These guys are hanging their butts out on the edge, and "Piston? No thanks." was the answer. "Runs cooler and cleaner" didn't make the cut.
 
To Tirods point.

A piston just moves the cleaning somewhere else.

Instead of having to clean the crud off the bolt tail, you now have to clean the crud off the piston and out of the piston cylinder.

If you have a piston gun and you aren't cleaning your piston/gas block you are asking for your piston to sieze and you won't be able to just keep cramming lube into the gas ports to keep it from cementing in place like you can with the AR. You actually need to get in there and scrape that crap out. You might get by with it for a while but eventually that same carbon build up that everyone complains about in the BCG of the AR can glue your piston to the walls of the cylinder.

Now instead of just taking the guts out of the rifle, you now need to take the guts out AND the piston.
 
^^Hehe, exactly!

Once again this debate has devolved into, "Our facts are better than your facts."
Any whisper of a critque of the AR15 system is blasphemy.

Just arbitrary: Say a guy burns a thousand rounds and it's several days before he has time to clean the weapon. Then away he goes again, all clean and happy. If there aren't jamming problems with that sort of usage, what's to improve?
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There is always room for improvement. That's is what evolution is all about.
Discounting any possilble critiques of any weapon system is not the way to win future battles.

Kool-aid has a detrimental effect on invention and improvement:rolleyes:
 
Jo6pak, it's not a matter of critique = blasphemy. Critique is fine, but there needs to be some sort of real-world empirical evidence before judging that something is indeed better than what was the prior method.

Folks have been arguing back and forth for years about DI vs. piston. There seems to be no evidence that one is better than the other. Opinions ain't evidence. The plural of anecdote is not data.

And if I come across as grumpy, it's because this is about the umpty-leventh thread on this subject--and with no more definitive conclusion or concensus than in any of the previous threads.
 
I think some people are just horrified when they field strip their AR15 after 100 + rounds, and see just how dirty the bolt and BCG is. Just knowing it gets that dirty bothers them. "if it is that filthy after just 100 rounds, how can I trust it to go 500 rounds ?"

Many machines are capable of operating to their spec and at full capacity even though they are quite filthy. The AR-15 action is not unique. The inside of a diesel engine would be considered filthy by anyones definition. Yet that engine might go 10,000 or more hours with no internal cleaning, just periodic re-lubing.

It is not magic that an AR-15 can operate in a perpetual state of filth, as long as it is kept lubed. When I say filth, I mean carbon-fouled lubricant. This fact has been demonstrated a number of times, and the prior thread (now closed) talked about a gun called "filthy 14". I had never heard of it before that thread, and it is a fascinating story. It is not magic because many other modern machines are the same way... machines that are a lot more complex than a self loading rifle with just a few moving parts.

For some people (but certainly not all) the attraction of a piston system is that it runs cleaner... even though the filth is not a reliability problem, any more than the black filthy oil in a diesel engine is a problem. But if they can't get comfortable with THE IDEA of all that filth. So I am glad that there are piston options available to these folks. We all need to be comfortable with our weapons, and if it takes a piston, well that is what it takes.
 
I have to say, that's a very reasonable view. Now if the DI guys would only realize that there is absolutely no reason that they have to run a dirty gun :eek:. SUIT ON!
 
You can coat me in carbon i don't care how dirty it is. Another 1000$ for a reputable piston system in the light of a clear conscious that my gun is clean and my bolt carrier cool enough to touch isn't going to cut it. Attach a suppressor and you'll see them both get pretty dirty.

It would be different if reputable piston manufacturers like POF, LWRC, HK, Barret, etc. Were around the same price as BCM, DD, LMT, etc. I'm not including LMT because it's simply a piston conversion.

I mean even if i were a "neat freak" about my weapons still couldn't stomach dropping another grand for something so tedious.

Parts is also a problem i don't want to be subject to a certain manufacturer because the piston design isn't standardized and everyone's design for the most part is different.

Just how i see it. To each their own.
 
I am completely with you Blackops_2... I just recently bought my first AR, and after researching and thinking about it for nearly a year, I went with a standard mid length DI with a 16 inch barrel. The slight advantages to a piston system did not outweigh the negatives (non-standard parts, cost).

Honestly, I don't find the AR to be that hard to clean. I only shoot about 200 rounds per trip to the range, so I am not a heavy hitter like some foks on this forum are. But I thouroughly clean my AR (and every firearm I own) every time I shoot it.

I spend more time cleaning the bore than I do the bolt carrier group. I find the BCG cleans right up, and I just use plain-jane break free CLP. If I owned a piston gun, I would still have to clean the action... it might be a little less dirty, but it would still need to be cleaned. And the bore would still be the most time consuming part of the job. Cleaning an dirty AR-15 is no worse than giving a revolver a good thorough cleaning.

But some people obsess about things and everyone wants choices ... that is why we have so many choices in caliber. so many choices in bullet types. so many choices in scopes and optics. so many choices in holsters.

If it takes a op-rod on top of your barrel to give you confidence in you rifle, by all means, don't let us stop you. If you need a 6.8 mm projectile to give you confidence, go for it. Don't want to shoot at deer with anything less than a 30-06, it's all good.

But let's not invent reasons out of thin air to make our choices seem more than what they are. It's a personal preference, that is all. My choice of "A" does not invalidate someone elses choice of "B".
 
It's really not an issue of piston vs DI - it's a issue of making a weapon that functions under all conditions - including when it's dirty.

The M16 has had a problem with dust and dirt from the day it was made - which is why it has a dust cover over the bolt. The M4 addressed a number of problems with the original design, but it is still finicky about being dirty.

The Army is trying to find a weapon that runs just as well when it's dirty because sometimes you don't have time to clean the weapon, and other times it gets dirty during a mission and you have to shoot the rifle when it's dirty.

In their own words:

3rd ID soldier: “I know it fires very well and accurate [when] clean. But sometimes it needs to fire dirty well too.”

25th Infantry Division soldier: “The M4 Weapon in the deserts of Iraq and Afghanistan was quick to malfunction when a little sand got in the weapon. Trying to keep it clean, sand free was impossible while on patrols or firefights.”

82nd Airborne Division soldier: “The M4 is overall an excellent weapon, however the flaw of its sensitivity to dirt and powder residue needs to be corrected. True to fact, cleaning will help. Daily assigned tasks, and nonregular hours in tactical situations do not always warrant the necessary time required for effective cleaning.”

75th Ranger Regiment member, SOCOM: “Even with the dust cover closed and magazine in the well, sand gets all inside; on and around the bolt. It still fires, but after a while the sand works its way all through the gun and jams start.”

As for Colt having a manufacturing advantage - FN makes FAR more weapons on a world wide basis than Colt. Hopefully, Colt has improved their manufacturing facilities since the last time I toured them because the equipment they had was OLD and the gun manufacturing process took a lot of hand work (costly) instead of machine work (CNC now making it cheaper than hand work).

You can argue DI or piston all you want, but the problem is not HOW it works but can it work dirty. The piston design helps eliminate one source of dirt (gasses / unburnt powder), hopefully giving the gun the ability to function longer when dirt and dust are introduced into the rifle.

If you can make a DI work WITHOUT the cleaning currently required - the Army would buy it. If the gun needs a piston to work - the Army will buy it.

It's about two things:

1A. - Budget and cost
1B - Will the rifle function when dirty (technical performance).

Usually (at least my experience with government contracts), 1A (cost) will always win out over 1B (technical performance).
 
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