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Posted: 10/11/2006 7:09:26 AM EDT
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I've been reading a bit about some of the piston uppers that are gaining popularity (HK, L-W, POF). It seems pretty promising. But I've also seen a lot of people on here say that it's a fad that comes around every now and again and never goes anywhere. Lots of people seem to think it's a solution without a problem. It's the age old "I'm crusty and won't accept anything newer than forty years" vs. "The M16/AR really sucked big until we fixed it" debate. I've heard a lot of reasons to be pro-piston (cleaner, less maintenance, less lubrication, no gas key). The arguments for gas impingement seem to be that it works fine and always has. Does it have more concrete advantages (other than cost  ), or is it just a case of, if it ain't broke, don't fix it?
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Impingment's advantages: 1) Cheaper 2) Less Weight 3) Standardized parts 4) Mechanically simpler/fewer parts 5) Allows for 'free floating of the barrel' w/o any interefenence from the piston system, which should make it easier to get a more accurate rifle. 6) True 'boreline' thrust (which theoretically be better for wear of the bolt and bolt carrier - but how much (if any) is anyone's guess. However you've noted some of the piston's advantages - one of which should be a cooler bolt which should help increase it's life (thus offseting advantage #5 of impingment?) IIRC #2 was the primary reason why Stoner went with impingment. |
Not that I have the money to go w/ a piston rifle but if I did...at this point I wouldn't buy one. My main reason is...my DI system works great and it's good to me and if I need parts for it...well lets just say I'm not gonna lose an arm and a leg paying for them. It's like buying a first year car model. You should always wait til the 2nd or 3rd year to buy that model so they can get all the bugs worked out. If you don't hear about it in 2 to 3 years upon release...well then you'll know 
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My only inhibition is that if my DI system breaks I can easily (and cheaply) replace those parts (gas tube, gas rings, etc). Those parts are also standardized thanks to the US military. BTW, of all DI parts I've EVER had to replace in 14 years of AR-15 ownership it has been ONE gas ring! With the piston system: you first pay for the new piston system then for whatever those parts cost if they ever break. Most likely you will have to go to the manufacturer for spares. Being SHTF centric, I lean toward the status quo direct impingment just to KISS. However, if the US military adopts a piston system I would immediately consider it. I'm really waiting for the civilian FN SCAR if guns aren't completely banned by then. |
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So far, sounds like the drawbacks to the piston system are all related to its newness. Which I agree is a good reason to hold off. Let's say we're ten years down the road, thought. The piston is widely used by the military, parts are readily available, the prices have come down somewhat, and they've shown themselves to be just as reliable. Do you get one? Do you switch most of your ARs over? Or do you stick with the gas impingement system? |
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I think they certainly make for a cleaner system, but I don't think they are any better. I qualified yesterday on some M16A2's that were extremely well used. They were loaned to us with at least a few hundred rounds down the pipe each already. The parts were worn gray all around. Besides one rifle with a broken extractor, they all ran without a hickup. |
FN SCAR (civilian) Adopted by USSOCOM (military version) and will probably be the standard US service rifle/carbine in the future One piece upper with integral picatinny rails Free float barrel interchangeable barrels and calibers folding and collapsable stock short stroke gas piston (corrected damn it!) Take M-16s mags What more could you want? |
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When I first got into guns, I was pretty skeptical of how the system worked, pistons make sense, and this gas imp. thing didn't really. So I went with piston guns. It took me a while, like 14 years of gun ownership to come around and take a closer look at the AR and it's gas system. It really is a beautiful, simple, elegant system. The piston is still there, the bolt just doubles as the piston, the carrier acts like the cylinder or gas block on an AK, and the elimination of all that mass and the redirection of forces into a straight line are the benefits of this. There are so many little ingenious features of the AR that make it a stand out compared to all the other guns out there, and ever since, all other guns have ben trying to keep up. |
A Robinson XCR?
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The XCR is probably nice but at least the FN SCAR has been adopted by USSOCOM and I predict it will eventually become the standard US service rifle/carbine in the future. Besides, I've heard horror stories about Robinson Arms customer service. |
Have you ever seen an AK? Explain the short strokness of the AK please |
I disagree. I think the .mil uses them and a large number of people use them because they work well, are fairly lightweight, decently powerful, and easily expandable. Correlation, yes, but causation, not so clear. |
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Agreed. I think there's a whole host of good reasons the military uses them, and most of those reasons are just as valid for private owners. Getting to practice with the platform whenever you want using your own hardware instead of waiting to get ahold of Uncle Sam's rifles is also a plus in the event you aren't infantry but want to keep those AR skills up. 
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"As it turned out, FN SCAR rifles are not based on any previous weapons but designed from the scratch. In all variants FN SCAR rifles feature gas operated, short stroke piston action with rotating bolt locking. Bolt system appears to be somewhat similar to that of FN Minimi / M249 SAW machine gun. This system apparently is less sensitive to fine sand, dust and any other fouling inside the receiver, than any system with M16-type multi-lug bolt and plunger-type ejector. " From World Armed Forces Technology Forum |
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If you go with LWRC's piston rifles.....there's a lifetime warranty on the parts. If it breaks, they'll replace it. Perhaps there's legal loopholes in their wording, but as long as they don't go under, I'm pretty sure you'll be able to get your rifle fixed. I have two piston uppers from LWRC I'm going to take out for the first time tomorrow (finally got my tax stamp!!! ). I've only had experience with DI until now. I'll letcha know my impressions tomorrow. The one big advantage I see to GP uppers is for SBRs. With the shorter bbls, it's harder (but LMT has proven it's not impossible) to make them run as reliably as the longer ones. GP helps in that regard IMO. JMO, Sean |
Funny because how long were the SOF community using the CAR-15 type carbine before the M-4 became the widely issued in Army? The Marine Corps originally thumbed down the M-4 in favor of the M-16A4. But M-4's were procured for the Recon & LAR communities and now they are within the infantry battalions for squad leaders, platoon commanders etc. If it works for USSOCOM my money says they will eventually find its way down the high speed ladder to the infantry communities. |
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It's one of those, "I'll believe it when I see it" things. Remember the XM8 was supposed to be the "next" rifle for the Military a few years ago. I believe the SCAR will follow the same fate. SOCOM would probably issue the HK416 before it would the SCAR. The HK416 is already issued to the Army's Tier One Unit. SOCOM and the rest of the Military are continually evolving the M16, M4 and it's variants to meet it's needs. That is one of the advantages to the M16 series. They also have a lot of money wrapped up in it with all of the parts and accessories etc etc. It will be a LONG time before it goes away. For the DI vs Piston debate. I haven't drank the Piston kool-aid just yet. The only advantage (in my eyes) is that it's somewhat easier to clean. For one, the DI guns are NOT difficult to take care of. Some people say that the Pistons are more reliable with the 10.5" barrels, my LMT 10.5" runs 100% and that's hard to improve on. NSW is obviously happy with the DI 10.5" uppers or they wouldn't be ordering them by the thousands. |
This is got to be a big  SOF was using the CAR-15 because the AR-15 had been adopted as the primary infantry rifle. The M4 carbine has not displaced the rifle from it's role. |
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It vents the gas after a short distance... thats what a short strok is. An AK is by definition short stroke whether people like it or not. |
Umm the XM8 did not win a contract for rifles... the SCAR did. Oh, and the 416 has not won a contract either to my knowledge. SOCOM's new rifle WILL be the SCAR. |
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Would it be cool to show my shootin' buddies my ϋbertacticooloperator® PISTON UPPER? You're damn skippy!!!  Would I pay my own money for one, and more to the point, enough of that money to buy a decent suppressor or a WHOLE NEW AR??!? Not a chance in h311...  I find myself shocked to be more or less in agreement with markm for once 
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Don't fuck with his Colt fantasy. |
I sincerely hope my post wasn't taken that way......I specifically mentioned LMT b/c their 10.5" uppers run so well. From what I've read on the "error"net though, I'd have to surmise that reliability is *generally* less with the shorter bbl (10.5/11.5) ARs. Hope that clarifies my comment. Sean |
AH HAH!!! This is from Wikipedia! There are four principal types of gas operation: short-stroke, long-stroke, gas trap, and direct impingement. A short-stroke gas system is defined as one which uses high pressure gas from the middle portion of the barrel that impinges on the piston head for a short period of time before excess gas is either cut-off (M-14) or vented (AK-47) or the piston head reaches a stop (M1 Carbine). The distance the piston travels under pressure is generally less than its diameter. The piston may or may not be attached to the bolt carrier. This is the most common type of gas operation. A long-stroke gas system is generally defined as one which the stroke of the piston under pressure is greater than its diameter. Because of the greater dwell time, gas must be ported from the barrel very near the muzzle of the weapon as in the M1 Garand. This relatively lower pressure gas acts over a longer period of time to impart the same amount of energy to the operating system. Because the operating parts are longer, they are necessarily heavier and this system is not used in modern weapons. A gas trap system is similar to long-stroke operation, however gas is 'trapped' after leaving the muzzle. The "Bang" rifle and early "gas trap Garand" rifles use this system. The German MG-42 machinegun and other recoil operated weapons use this energy in combination with recoil energy for more reliable and energetic operation of the weapon. The gas trap system is also obsolete. The direct impingement method of operation vents gas through a tube to the working parts of a rifle where they directly impinge on either the bolt itself as in the M16 rifle, or the bolt carrier proper. [edit] Notes on operation The terms 'short-stroke' and 'long-stroke' are often confused by both laymen and experts. The 'stroke' is that portion of time when combustion gasses contact the piston head prior to venting. It is not the total length the piston head might travel during the cycling of the action. The commonly reported misconception is that a piston being rigidly affixed to the bolt carrier is what constitutes a long-stroke system. In fact, the 'stroke' is virtually the same for both the mislabeled 'long-stroke' AK-47 and correctly labeled short-stroke AR-18; the gas port is in nearly the same location along the barrel. The description of the AK-47 and others with pistons attached to bolt carriers as being of long-stroke operation is erroneous. |
I never said the XM8 got a contract. Please show me the contract that FN got for the SCAR. To my knowledge the SCAR has only been selected for further tests. Just because there is a solicitation for X amount of SCARs does not mean that SOCOM has to buy them all. Last I heard they were only obligated to buy 25 SCARs. I believe that the SCAR program went "Joint" and that will add YEARS to the trials if it ever happens. Someone correct me if I'm wrong.
Once again, I never said that 416 did. I said that they are ISSUED to the Army's Tier One Unit. As I'm sure you know , some Units in the Military do their own testing and get what they want.
Like I said. I'll believe it when I see it. |
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