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Thread: Piston or Gas?

  1. #61
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    Quote Originally Posted by CoolBreeze View Post
    LMT's and LWRC's have their bugs too.

    I know both have accuracy concerns, the LWRC apparently shoots quite differently as it heats up or cools off.
    Mine certainly doesn't. Just this last week, I dumped 4 mags through it as fast as I could pull the trigger. It got DAMN hot, but POI didn't change at all.

  2. #62
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    Quote Originally Posted by Thomas M-4 View Post
    Out of curiosity does LWRC use a different bolt or does it a standard style bolt?
    It works just fine with a standard bolt, but new ones are shipping with an "enhanced" bolt (With a whale tail style extractor).

  3. #63
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    That link you gave I read over 2 years ago It has nothing to do with LWRC ,HK , LMT, or any other gas piston AR. It does mention the FN SCAR [ A SHORT STROKE PISTON ASSAULT RIFLE DESIGNED FROM THE GROUND UP AS A REPLACEMENT FOR THE M-4 IN SOCOM ] . Have you read this entire thread?? Because I am only talking about adaptations..

    Are you trying to point out the bolt failure at 6,000 - 10,000 rounds ???
    Did you know barrels only last to 6,000-10,000 rounds ???
    Did you know that when you replace the barrel that you also replace the bolt???
    What is your point with that link???

    The proprietary bolt carrier that LWRC has that uses the slight downward slope [THAT RE-VECTORED FORCES INSURING INSURING THE CARRIER IS PUSHED STRAIGHT BACK] your own words. WHERE DOES THE FORCES GO???????????????? THEY GOT TO GO SOME WHERE RIGHT.. Do you want a hint?? They go to the gas piston/ pushrod that is pushing your carrier to the rear. Can you show me a SHORT STROKE GAS PISTON DESIGNED FROM THE GROUND UP THAT PUTS TORQUE INTO THE GAS PISTON/ PUSHROD THAT WAS A SUCCESSFUL DESIGN ???


    The great thing is SETH HARNESS [HAS DESIGNED THE BEST ANTI TILT BOLT CARRIER DEVICE THAT I HAVE SEEN TO DATE BETTER THAN THE SKID PADS AND BETTER THAN THE ANGLED KEY THAT VECTORS FORCES HIS DEVICE SPREADS THE FORCE ACROSS THE CARRIER BUFFER & BUFFER TUBE.

    Why does every body that has piston systems keeps throwing up round count numbers to me??? I dont care if YOU HAVE 1,000,000 ROUNDS THROUGH IT.
    I NEVER EVER SAID ANY THING ABOUT FAILURES I HAVE STATED THAT MORE THAN ONCE THAT I AM MERELY POINTING OUT DESIGN FLAWS.
    By the way for those people that do not know the difference between FORCES AND TORQUE THEY ARE THE EXACT SAME THING.

    This engineering class 101 has been going on for days If you most know every detail about this I suggest you get in SCHOOL.. ITS $330 A CREDIT HOUR.

    By the way the enhanced bolt that you say is in your LWRC I HAVE THAT EXACT SAME BOLT IN MY M-4 CARBINE ITS MADE BY LMT I AM ALSO RUNNING THE ENHANCED CARRIER DO YOU KNOW WHAT ITS SUPPOSE TO DO???
    Its suppose to reduce the stress on the bolt that runs in a carbine gas system.

  4. #64
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    Quote Originally Posted by Sttrongbow View Post
    I'm interested in your buffers... are you gonna offer them for sale?
    Yes,
    working on that and starting a company at the same time.
    There is a thread on these buffers here as well. Link



    Do you have a basis for that opinion, or is it just a "gut feel" kind of thing?
    The way I see it is, bolt carriers were designed to travel down bearing surfaces in a linear path with little to no tilt. Now, take that same carrier, force a bind on it and send it down the same path with nothing to hold it straight through its cyclic motions. The rear of the bolt carrier has to be held in place somehow, especially when the bearing surfaces on that carrier only measure something like 2 3/4" to control a 7"+ bolt carrier (when bolt is fully extended).



    I hear ya, but I assess such matters as a matter of function... do they compromise the function of the rifle over its useful life?
    "Usefull life" is a relative term. Two guys with the same gun are going to have different usefull lives. My answer to this question would be along the same lines as the last answer... How much binding can the current AR system take with this piston technology applied to it. I dont know, but Im not going to wait for parts to wear out or possibly break prematurely to find out. I believe this is the best fix for the tilt issue. Its positive, constant and drop in. Bearing surfaces are not made to bind, tilt is proof that bearing surfaces (among other things) are being stressed more than a DI system. Within the current parameters, Im not comfortable with that. Unless Im coming from left field, it seems like common sense to me.

    Thanks for your interest,
    Seth H.

  5. #65
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    wrong

    Quote Originally Posted by Thomas M-4 View Post
    By the way for those people that do not know the difference between FORCES AND TORQUE THEY ARE THE EXACT SAME THING.

    This engineering class 101 has been going on for days If you most know every detail about this I suggest you get in SCHOOL.. ITS $330 A CREDIT HOUR.

    Maybe you should go back and take it yourself, or at least ask for your money back. That way you would understand that force and torque are not the same thing. The term 'Force' is used to describe linear kinetics whereas 'Torque' implies angular kinetics. The formula for force is Force = mass x acceleration whereas Torque actually uses force as one of its derivatives, Torque = Force x the length of the moment arm (d). Someone who truly understands mechanics would never use torque and force interchangeably.

    If you are going to talk down to people, at least define your damn variables correctly.

  6. #66
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    Maybe you should go back and take it yourself, or at least ask for your money back. That way you would understand that force and torque are not the same thing. The term 'Force' is used to describe linear kinetics whereas 'Torque' implies angular kinetics.
    thank you for posting this TRUTH, this is one of the first things i learned in the U.S.Navy as an 18 y.o. jet engine mechanic.., and i do not hold a college/university degree !

  7. #67
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    Quote Originally Posted by jwinch2 View Post
    Maybe you should go back and take it yourself, or at least ask for your money back. That way you would understand that force and torque are not the same thing. The term 'Force' is used to describe linear kinetics whereas 'Torque' implies angular kinetics. The formula for force is Force = mass x acceleration whereas Torque actually uses force as one of its derivatives, Torque = Force x the length of the moment arm (d). Someone who truly understands mechanics would never use torque and force interchangeably.

    If you are going to talk down to people, at least define your damn variables correctly.
    First my engineering degree IS NOT IN MECHANICAL ENGINEERING.
    Forces used to describe liner kinetics. Torque implies angular kinetics.
    ANGLED CARRIER KEY THAT VECTORS [FORCES] ANGLED KEY.... AND TORQUE IMPLIES ANGULAR KINETICS your own words you still have torque being transmitted into the pushrod. Look I am sorry if you got up set at my response last night I APOLOGIZE I did not intend this to get into a flaming match. I just was pointing out design differences that I do not agree with along with some marketing hype thats been thrown around. Really this horse has been beaten to death time after time. I say again I APOLOGIZE TO YOU IF MY RESPONSE SEEMED MEAN. I really believe I have had too much of this thread.
    So I am done with this thread.
    Thank You

  8. #68
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    Quote Originally Posted by jwinch2 View Post
    Maybe you should go back and take it yourself, or at least ask for your money back. That way you would understand that force and torque are not the same thing. The term 'Force' is used to describe linear kinetics whereas 'Torque' implies angular kinetics. The formula for force is Force = mass x acceleration whereas Torque actually uses force as one of its derivatives, Torque = Force x the length of the moment arm (d). Someone who truly understands mechanics would never use torque and force interchangeably.

    If you are going to talk down to people, at least define your damn variables correctly.
    well i have to agree

    F=mA were F is force in vector form and A is acceleration in vector from

    torque is a moment arm F times length so yes for is a torque is a function

    now in the case of the piston ar we must also include vibration and piston deflection it become a anctual FEA analysis problem

    in order to determine the amount of force on the piston we need to know the pressure build at the front of the gas piston. this force translate to the bcg via the piston rod which will undergo deflection under load. this deflection is what causes the bcg to undergo tilt.

    this does not happen with the DI system because there is no deflection rods. the gases are directed and allowed to escape. the almost immediate escape of the gases prevent any residual pressure to tild the bolt.

    now one major fix to this is either to make the bcg and piston one complete unit
    but ultimately the best way wold be to increase the diameter of the piston rod in order to minimize deflection. this becomes an issue with the ar design because of the lack of space .

    if u guys want a FEA analysis give me a bit of time so i cam finish finals and i will gladly post it up

    now this is my eng. 2c and my major is mechanical eng. deseign

  9. #69
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    Quote Originally Posted by Thomas M-4 View Post
    First my engineering degree IS NOT IN MECHANICAL ENGINEERING.
    Forces used to describe liner kinetics. Torque implies angular kinetics.
    ANGLED CARRIER KEY THAT VECTORS [FORCES] ANGLED KEY.... AND TORQUE IMPLIES ANGULAR KINETICS your own words you still have torque being transmitted into the pushrod. Look I am sorry if you got up set at my response last night I APOLOGIZE I did not intend this to get into a flaming match. I just was pointing out design differences that I do not agree with along with some marketing hype thats been thrown around. Really this horse has been beaten to death time after time. I say again I APOLOGIZE TO YOU IF MY RESPONSE SEEMED MEAN. I really believe I have had too much of this thread.
    So I am done with this thread.
    Thank You
    So, not being a mechanical engineering student relieves you of your knowledge of introductory physics? I'm sure your professors are quite proud to have you as a student. If my undergraduate or graduate biomechanics students didn't know the difference between force and torque they would fail my class. Furthermore, the engineering students who take my class as an elective typically understand basic physics quite well regardless of what kind of engineer they intend to be. Perhaps it is just you...

    If you did not intend to start a flaming match perhaps you should avoid calling people out and telling them to go back to school on internet forums in the future. Snide comments like that have no place in mature discussions. Plus, it helps when you know what the hell you are talking about. Less talkie-talkie and more study-study for you, especially since finals are so close.
    Last edited by jwinch2; 04-26-09 at 13:46.

  10. #70
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    This thread reads like some have lost track of a few things.

    Just adding a gas piston system to an AR does not automatically make it inherently more reliable. The advantages of a gas piston system is just a piece of the puzzle, and even then might only make a difference if certain very specific parameters are introduced (Barrel length less then 14.5", lots of suppressor use, use of varying quality ammo, ETC). More important is the rifle itself. The HK416 gets such respect by those who truly know becuase it is such an extremely high quality AR. Not just becuase it uses a gas piston system. Look one over sometime. You will find proof marks indicating the level of testing, highest quality materials, and QC all over it. Not to mention the high level of testing the rifle went through before it was adopted. These are indicators of a quality weapon system that has stood the test of time and real world use.

    Why do you guys think we see such varying opinions on other gas piston AR rifles? Hint: This is an indicator of varying quality from rifle to rifle. These are tiny companies and without question are at the mercy of there parts suppliers. Thus they have to take what they can get and without the engineering & QC support of larger companies this effects there quality/durability. They also know very few of there rifles will really be shot all that much so it is a calculated risk. Engineering staff, experienced QC departments, and hundreds of thousands of rounds of ammo for durability testing is very expensive. That's why for the most part they let customers do there testing for them.

    If you have purchased a gas piston AR from a certain manufacturer and it has proven itself reliable over high round counts, good for you. But always keep in mind that there are guys on this forum who have had the exact opposite experience. You got lucky and got a good one. The guy right behind you in line might have gotten a dud, even if he has not shot it enough to know yet.

    As already stated buy a high quality AR from Colt, Daniel Dense, Charles Daly, Noveske, or LMT and 99% of us will be perfectly happy.
    Last edited by VA_Dinger; 04-26-09 at 16:01.
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