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Posted: 5/29/2006 11:48:59 AM EDT
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I was wondering perfomance wise, is there any real diference between a say piston op M4 and direct gas M4? Any of you guys ever actually experinced REAL LIFE diferences?. I mean like for example trying some ammo that was giving you trouble in a direct gas M4 (short stroking) and that's working perfectly in a piston M4. Any of you ever done that? results, pictures, experiences? Asking this because i know there's some ammo my M4 just wont work with, while other rifles will, like my mini14 or my 20 inchs AR. The thing is that when my M4 doesn't like a certain type of ammo, it will shortstroke everytime i fire it, sometimes failing to eject (so far one brazilian brand-type). Yes, i'm sure, i have eliminated LOTS of variables, it's just shortstroking and only with that type of ammo. The funny thing is that that same ammo WILL work in my mini14 and 20 inchs AR....anyways back to the piston subject...has any of you experinced any positive results after having compared them two sistems other than one stay cleaner than the other? just for the record i'll add than i've had ZERO malfunctions out of that same colt m4a1 using other brands of ammo. HUNTER. |
Yup, i know. Just wanted to take the oportunity to say you guys are the shit.  HUNTER. |
Thank you sir  I don't have alot of experience with GP AR15's, but I have had a chance to play with the POF upper a few weeks ago. I ran a couple hundred rounds through it and the BCG was super clean when I was finished. It also was always cold to the touch. I was impressed. There are alot of folks on this board that can better explain the benifits of the piston system, but from what I read they make a SBR less finicky, maybe that would also yield a upper system that is less finicky with ammo choice ? I'll let folks with more experiences weigh in. |
Yeah, how about that, anyone? HUNTER. |
Well I have a POF P-415 16" upper that I have been using on a Bushmaster lower, and I can not seem to make this rifle choke, no matter what ammo I run through it. Thus far I have tried: Cor Bon 55 Grain .223 JHP Wally World WWB 55 gr 223 Wolf 55 & 62 grain FMJ & HP .223 Remington 55 gr JSP and HP .223 TAP FPD 75 gr .223 Monarch .223 55 gr steel case WWB Q3131 5.56 Lake City SS109 62 gr 5.56 Radway Green 1992 Head Stamp 63 grain from AIM Surplus The only ammo that gave me issues was Monarch Steel Cased 55 grain ammo from Academy. It tumbled so bad, I had a hard time hitting my target @ 100 yards. I brought the target in to 25 yards, and noticed that it was impacting the board sideways 4 to 5 inches off from the point of aim. The POF rifle DID NOT CHOKE, it just couldn't stabalize this POS ammo. I shot this same Monarch .223 in my Bushmaster 16" HBAR, and it fouled up the action so bad, I couldn't even run a full mag through the rifle without a failure to eject. The pros to the POF: The Bolt and Carrier were barely dirty after 500 rounds Minimal lubrication was required for smooth functioning The upper recoils with more of a straight back push than a upwards flip (To me this is a pro for rapid follow up shots whereas to others this is a con) The upper reminds me of an AK in that it will shoot anything I put through it without choking. The cons: Mag dumps make the gas port, fsb, and front handguard retainers VERY HOT and will burn your fingers and/or melt certain gloves. I noticed vertical stringing when the rifle heated up. This upper tends to group better with heavier ammo. The 75 grain TAP FPD has given me the best groupings to date with one small jagged hole at 25 yards and a slightly bigger hole at 50 yards. I haven't tried at 100 yards yet because I am waiting for more ammo to arrive. ETA: Other than the Monarch Ammo Issues, my Bushmaster 16" 1:9 HBAR shoots right up there with my POF. Naturally, the Bushy is way dirtier after 30 rounds than the POF is after 300, but that is just the nature of the DI system versus the Piston system. |
Then i take it that for you, Sigs, HKs, FALs, AUGs are third world rifles? I'm not saying it's a solution or anything even close to that, I'm just asking for experiences from using them piston uppers and or comparisons between the DI and the Piston system using diferent types of ammo that perhaps can hicup in a DI system and work in a piston one. re-read my thread please. That analogy just seemed like....well bullshit. HUNTER. |
So AR-18s [designed by Eugene Stoner] are 'Third World Rifles'? Are Mk16s and Mk17s 'Third World Rifles' too? F2000s, G36s, and L85s as well? Colt is even going to make piston uppers for gawds sake, I guess they make 'third world rifles' too? I can't believe the irony that AR-15ers are now suffering the same 'Not Invented Here' syndrome that the M14 Freaks had back in the 1960s. After all, everyone knew that 5.56mm ammunition, direct gas systems and those silly M16s were just a fad  .I swear, when the army replaces the M16 [within a decade], half of this board is gonna commit suicide. |
The Colt also has a monolithic rail system, unlike POF or L-W. If and only if, Colt offer their 102X in 6.8SPC will I bite. As for the last comment, change is just like death and taxes. A piston system itself bring litlte to the table. A caliber & rail system change is required as a minimum |
The G36 and L85 wouldn't be among the rifles I would pick if I were trying to make a case FOR piston rifles. The F2000, MK16, and MK17 are still in their infancy. We'll have to see how they pan out. I'm very much digging the specs at current though. The F2000 might be the first bullpup (aside from the AUG A3) worth owning. The AR18 is a little outdated, but a lot of people swear by them. I think that a US company should actually set out to improve upon the original and bring it into the 21st century. I've got to admit, after running the worlds crappiest ammo through POF, LW, and HK416 rifles, I'm impressed so far. I'm not giving up totally on direct gas, but I'm certainly not going to thumb my nose at anything that offers an improvement over something that's already so damned good. |
What are you talking about. The G36 operating system is one of the most reliable in the world. You just can't take advantage of it because the barrel will fall out when the trunions melt.
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Capt'n, unless there is a caliber change. The difference is in the noise. IMHO. A properly maintained weapon runs regradless, if its DI or piston system. |
So you do, but you claim the design is ten years old and not in it's infancy? (For anyone wondering what my point is, the F2000 wasn't available for sale until 2001.) |
Just because something isn't for sale doesn't mean it hasn't been around a while. ETA: the F2000 existed in several forms before it was even the F2000. There is a reason it was even offered for sale outside of the military. |
+1 The piston is a very reliable operating system for all the rifles that have it. I think MarkM is wayy off. Also, Blackwater tested this and said they were impressed also. If they think it is impressive, I go with their evaluation before an ARFCOMer. Sorry Markm, but I think their opinion trumps yours. |
The F2000 hasn't been available in it's current form for nearly long enough to say whether its viable or not. I'm not even going to stop laughing for long enough to type a more in depth response. |
No one was being issued, given, or sold F2000's until late 2001. If you have an inside line to FN's Belgian factory which was doing testing on the rifle, I would love to hear more. 2001 was five years ago, not ten. Condemning a rifle in it's developmental stages is ridiculous. The F2000 wasn't even on the open market until 2002, and I feel that definately classifies as being in it's infancy. |
| well it was the problem of the use of ball powder that was guming up the direct gas operation system during the vetinam era, but since ball powder is hardly used anymore, except for a few calibers, i really see no reason to get a POF except for maitentence purposes olny, not to mention the loss of ROF when going to a POF. |
The Colt LE1020 does not run mil-spec gas ports - in point of fact, the port size is dramatically reduced and the take off point is about an inch further forward than the carbine position. As for everything else, pay your money and take your choice. |
Well, however you want to argue it, "infancy" means there will be growth which is pretty obvious there won't be any with the F2000. FN shopped the F2000 to governments and has not been successful in getting adoption of the unit which is why they have turned it to LE and civi markets. It is pretty clear the problem with the F2000 is not the gas system but rather that it is a bull pup type design. |
I was not referencing the Colt LE1020 (Colt Gas Piston Model). I have no idea how that product is configured. I have seen one hanging on the wall at SHOT, but that is about it. I was referencing Hunter223 short stroking issues on his "colt m4a1", which I would guess would be a something between a LE6920 and RO977 or similar. At least that is the way I interpreted his initial post. |
Okay, just wanted to clarify that your negative comments towards it were your opinion and not fact. 
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That's why the PS90 has been made for the civilian market too, eh? 
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Yes. |
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I bought a POF upper mainly because I got tired of spending 2 hours cleaning my Bushmaster Xm-15, after about 300 rounds at the range. I have a POF upper on a Colt lower, but still take both rifles at the range...No difference in accuracy between the bushmaster and the colt with POF. The only thing it comes down to really (IMO) is when it's time to cleaning...the POF upper, esp the bolt assembly is way quicker and easier to clean than my bushmaster non- piston upper. Ammo tested at the range:(no malfunctions with the POF upper-approx 500 rounds total) Radway SS109's Wolf .223 62gr Blackhills .223 55gr Federal green tips Independence .223 55gr |
I don't know the exact designation of the COLT M4 barrel i'm running but it is midcontour under the handguards not heavy not light, and as far as short stroking issues i've experienced it only happened when trying to fire some brazilian so called military type of m855 (marked ss109). That ammo was DEFINITLY (sp) "weak" ammo since the gun wouldn't work while using an M16 bolt carrier but would when i slaped in a light AR15 bolt group. Here's a picture of the exact same barrel i'm using.  Eitherway, this thread was about gas piston REAL advantages. HUNTER. |
Went to hell in a hand basket real quick didn't it? My main reason for choosing a POF is that I saw it as the next evolution in AR design. In the past I have had issues with certain AR-15s not running right and it was usually related to the gas system (out of spec gas tube, improper staking of carrier, gas leak at key and carrier due to improper fitting, etc.). |
HKs (of the type most people here have) use blowback, not piston operation. HK didn't start with the piston-op shit untill the G36. The FAL & M14 are old designs, made when there was only blowback (HK, M2, M1919, StG-44, MP40, Thompson, etc) or piston-drive (M1, M14, BAR, FAL)... The Stoner gas system was produced a few years later in the AR-10.... The FAL has also been gone from 1st-world armies for years, due to use of the over-powered (for an assault weapon) .308 round, and although it's a good rifle, it's not an example for modern rifle design.... And the Aug is just... Odd... |
Two things. One as far as i remember the STG44 or MP44 is Gas operated, using a piston, just like an AK (the AK is suppoused to be some kind of a modern clone of this rifle). Second, you, like others are missing the point of this thread. HUNTER. |
what about the SIG 550 series, the FN FNC, FN F2000, FN SCAR .... ?? long list here, gas pistons seem to dominate world.guns.ru/assault/as00-e.htm |
| Given a choice , IF(big if) the cost and accuracy of a piston and direct impingement AR were the same, I'd go piston. The AR is my favorite all around rifle system,but the idea of BLASTING components that need lube with super hot gasses and then carbonizing that lube just bugs me. Then I've got to clean that mess up. As it is and given that the above is not reality, I'm waiting for the SCAR(L). We'll see.............. |
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Boy you started a S**t storm didn't you? I didn't want to get caught up in all the crap, but I thought I'd reply anyway and take the chance of getting flamed.... I have been a police officer in Georgia and South Carolina for seventeen years. I am a certified firearms instructor in both states. Along with other weapons, I own five AR15s, one of which is a DSA Z4 (POF upper w/DSA lower). I tell you this so that you can weigh my comments accordingly. I am by no means an expert, but I do have experience. I shot my "gastrap" AR for the first time using lake City 55 Gr. and it performed flawlessly although I wasn't happy with the average group size. I then used some very cheap South African surplus ammo and it "misfired" every other shot. The problem was Failure to Extract. Looking at the brass you could see where the extractor just ripped the rim off one side of the brass and it left the spent cartridge in the tube. Clearly the extractor was doing everything it knew how to do, but the ammo just wasn't up to the task. At first I thought maybe the bolt is trying to go rear-ward before the pressures had dropped sufficiently, but I have used several other brands of ammo since and it has yet to hiccup. To complicate your question even further, I would like to point out that I can run the same South African ammo in my 16" Rock River ("Tactical Elite") without a problem. The RR has the "Wylde" chamber and I suspect that this is the reason it can digest the stuff. However, this does lend itself to contradict the claim that a DI is less able to digest different ammo than a gas piston operated AR, but this isolated incident would be far from definitive. I did add an extractor O-ring to my "Gas-Trap" Z4 along with a RR 2 stage trigger. I can report that the POF upper is exceptional in both function and Finnish. My 25 and 50 yard groups are consistently one hole or slightly larger and the 100 yrd groups hover around 2-3 inches with the Black Hills 77 Gr."Blue Box". and Winchester 50 Gr. Ballistic Silvertips (Our duty issue round). Since then, the rifle has never "Misfired" and is, of course, a breeze to clean up. I don't know if this helps or not, but you asked....... |
The people I have seen who have the most benefit out of a piston driven AR upper are those who are using extremely short barrels. (10" or less) The AR's gas system begins to have some problems when you get it that small. I have been through my fair share of carbine training, and the SBRs always have the most reliability problems. I have seen some that are dead reliable with any ammo, but I have also seen others that would just jam constantly after a couple of hundred rounds. If you aren't shooting a super-short AR, the benefit is mostly theoretical in my opinion. My Bushy carbines have never given me a moment's trouble as it relates to the gas system. The only time they have ever choked was because of mag problems. |
Interesting, so if i got this straight you did have some ejection problems with some certain type of ammo using a PISTON AR while that same type of ammo was being digested with no problems by a DI system, correct? Would you risk by saying that your first problems on that new piston AR were gas related? Chamber? HUNTER. |
| I've got some experience with both. Spent several years in the USMC and cleaned plenty of M16's and subsequently AR15's that I've owned. Anyone who has any kind of extensive experience (i.e., experience defined as 10's of thousands of rounds), knows that the AR15/M16 is a dirty F'n rifle to deal with. Period. If there is one 'real' bitch I have about it, then this would probably be it for me. I know the weap in and out. My bro was out shooting his new M4 RRA (brand new in the box) and after 300 rounds you couldn't stick your finger in the bolt/chamber area without pulling out solid black fingers. On the other hand, my 415's bolt was still shiney with only a slight hint of anything. My hands were not dirty even after completely removing and handling the bolt. If you take care of your rifle correctly, then it takes several / a couple hours at least, to do it right. The Z4 has eliminated alot of cleaning that otherwise I normally have to do. The older I get, the more valuable my time is to me. Spending a couple hours at the range should equate to a couple more of cleaning. Hope this helps |
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Hunter, The answer is I don't know. I think the problem could be the chamber size or just the brass on the ammo itself or a combination of both. Like I said, I'm no expert and there are people on this site that are much more qualified address this then I am. I do know that I haven't had any other failures to EXTRACT with any other ammo since. I just assumed that because my RR has the Wylde chamber which I understand to be a cross between a 5.56 and a .223 along with the fact that this is cheap South African ammo and that the specs could definitely differ from country to country or manufacture, that this could be one explanation. What if the neck size, taper or case length were out of spec. I really believe that the brass was just too soft or brittle or out of spec, but that doesn't explain why the RR digested it unless the "looser" RR Wylde chamber allowed for, or compensated, for the suspected bad ammo. Because this is a "new" operating system, one other part I questioned was how quickly the bolt started it's rearward movement in the POF (gas Piston) rifle as opposed to the RockRiver (DI). I have no way of knowing this, but I wondered if the pressures in the RR have dropped more than POF at the time the bolt starts its rearward travel thus the extraction of the spent case would be easier for the RR. All of this is speculation on my part. For the record, I do know that the POF upper is an exceptional piece of craftsmanship thats shoots VERY well with any ammo other than that particular one. Given what I paid for the 1000 rds of cheap stuff, I strongly suspect the ammo. Moreover, I intend to purchase the POF lower when I can after seeing how well the upper was made. All of this long winded banter to say: Bad ammo, and a different chamber in the RockRiver....I think. |
Thank you for your time and patience HUNTER. |
Holy SHIT! It takes you 2 hours to clean an AR? A monkey could clean an AR in less than half that time. Maybe you need to invest in a manual or something. It takes me about 20 minutes to clean my AR's. |
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