Page 3 of 9 FirstFirst 12345 ... LastLast
Results 21 to 30 of 88

Thread: Can you cite specific failures of piston AR's?

  1. #21
    Join Date
    Oct 2008
    Posts
    6,162
    Feedback Score
    0
    Quote Originally Posted by Sttrongbow View Post
    Sarcasm, I assume?

    I have an LWRCi upper with a couple thousand trouble-free rounds through it....
    Now you have done it. The mere mention of LWRCI sends Markm over the edge.

    I have 3 piston guns in my stable - REPR, M6A2, and LMT MRP. All three are just as reliable as my other DI weapons.

  2. #22
    Join Date
    Jun 2006
    Posts
    175
    Feedback Score
    0
    Quote Originally Posted by Pax View Post
    I'm no expert, so wait to have this confirmed, however I'm fairly certain that a piston's place is on a 10.5" gun that simply wont stop short cycling, not necessarily a suppressed one. Here's a quote from an interview with John Noveske published on Defense Review:

    "I only run the guns with suppressors for testing when I did my comparison, and with suppressors, direct-impingement and piston-operated were both very dirty, ’cause the blowback comes to the chamber, not the gas tube." - John Noveske

    Full article: http://www.defensereview.com/noveske...view-part-one/
    Using a suppressor on a gas gun is often cited as a cause for increased bolt speed (force) which can only come from increased gas tube pressure on a gas gun, no?

    Use of a can lengthens the amount of time higher than ambient pressure remains in the barrel (and hence, gas tube) so it seems reasonable to say that the source of dirty overall is both from the barrel/chamber and gas tube. Obviously, the barrel will accomodate a lot more gas than the tube will in this environment and is connected directly to the chamber so maybe the amount from the tube can be considered negligible?

    I guess my pipe dream of pistons being great for cans is busted.

  3. #23
    Join Date
    Sep 2010
    Location
    Knightdale, NC
    Posts
    201
    Feedback Score
    0
    Hey OP, you don't expect to get many real answers do you?

  4. #24
    Join Date
    Jun 2006
    Location
    NoVA
    Posts
    10,780
    Feedback Score
    17 (100%)
    Yes:

    HK...cracked upper receivers when shot hard suppressed. Firing pin safety failures. Broken bolts.

    POF...highly worn receiver extensions which caused erratic bolt velocity which was causing failure to eject, failure to feed etc whenever the bolt carrier would get caught in the trough cause by carrier tilt. Cracked bolt, cracked log at top of bolt. Large amount of finish wear/gouging caused by front-top of bolt carrier dragging along the receiver bore as the carrier tilt. A temp fix is a new receiver extension and new upper receiver (two things that don't really wear out in DI guns by the way). One particular POF I've seen will not run on this one particular AR lower but on that same AR lower all DI uppers (7 different ones) worked just fine. Corrosive pitting of the gas piston and op rod. Broken bolt lug which got between the carrier and upper receiver and ruined the upper receiver which required a new receiver and new bolt.

    early ARES....bent op rod in less than 600 rounds on full auto on a 11.5" upper, due to spigot coming lose after the gas tube roll pin 'exited stage left'.

    LWRC...I've thus far fixed 4 lose barrel nuts, replaced heavy worn receiver extensions with this wear causing unusual stoppages (fixed with a new extension and anti-tilt buffer). Early ones had carrier keys coming lose before they key was integral to the carrier. On two early one I replaced two broken bolts (before Matech).

    PWS...lose gas block (2nd gen after moving away from a pinned gas block to a set screw gas block). Newer pinned Diablo style is much better. 1st gen I had the piston (which is attached to the carrier) came lose but I caught it before it caused stoppages.

    LMT...highly worn receiver extensions from carrier tilt causing unusual stoppages fixed with a new receiver extension and anti-tilt buffer. Lose barrels if not checked regularly.

    So to summarize what I've said in the past, If Eugene Stoner wanted the AR to be a 'gas piston' design he would have made it that way from the get go. Trying to make the AR15 platform a piston gun is like Chevrolet back in the day trying to make a good diesel engine out of the small block 350 (5.7L) engines ...it didn't turn out to well.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  5. #25
    Join Date
    Oct 2008
    Posts
    1,808
    Feedback Score
    18 (100%)
    Well said. Did the PWS experience less problems and parts breakage due to the fact it is a long stroke piston op and probably has a lower BCG velocity? Or is this an incorrect assumption?

  6. #26
    Join Date
    Apr 2009
    Location
    7488 ft.
    Posts
    2,458
    Feedback Score
    18 (100%)
    Quote Originally Posted by The_Biased_Observer View Post
    piston guns "failing" or "self destructing"
    I bought a CMMG piston gun (gen 1) during the Obamamania rush when people, including me, were buying everything with a trigger. It was NIB of course.

    Somewhere between the 10th and 20th shots of Federal XM193 ammo, the action locked up tight. TIGHT!! So I sent it back to CMMG. It was there a month or so and they sent it back as a Gen 2 gun. I could see that some parts were different while some, like the barrel, were the same. They did not charge for the repair. The gun did not come back with a work order that said what was wrong.

    At that point I was spooked and sold the gun for a big loss. The new owner said he really liked it so maybe Gen 2 was the magic that it needed.

  7. #27
    Join Date
    Sep 2009
    Posts
    312
    Feedback Score
    0
    Quote Originally Posted by Robb Jensen View Post
    Yes:

    HK...cracked upper receivers when shot hard suppressed. Firing pin safety failures. Broken bolts.

    POF...highly worn receiver extensions which caused erratic bolt velocity which was causing failure to eject, failure to feed etc whenever the bolt carrier would get caught in the trough cause by carrier tilt. Cracked bolt, cracked log at top of bolt. Large amount of finish wear/gouging caused by front-top of bolt carrier dragging along the receiver bore as the carrier tilt. A temp fix is a new receiver extension and new upper receiver (two things that don't really wear out in DI guns by the way). One particular POF I've seen will not run on this one particular AR lower but on that same AR lower all DI uppers (7 different ones) worked just fine. Corrosive pitting of the gas piston and op rod. Broken bolt lug which got between the carrier and upper receiver and ruined the upper receiver which required a new receiver and new bolt.

    early ARES....bent op rod in less than 600 rounds on full auto on a 11.5" upper, due to spigot coming lose after the gas tube roll pin 'exited stage left'.

    LWRC...I've thus far fixed 4 lose barrel nuts, replaced heavy worn receiver extensions with this wear causing unusual stoppages (fixed with a new extension and anti-tilt buffer). Early ones had carrier keys coming lose before they key was integral to the carrier. On two early one I replaced two broken bolts (before Matech).

    PWS...lose gas block (2nd gen after moving away from a pinned gas block to a set screw gas block). Newer pinned Diablo style is much better. 1st gen I had the piston (which is attached to the carrier) came lose but I caught it before it caused stoppages.

    LMT...highly worn receiver extensions from carrier tilt causing unusual stoppages fixed with a new receiver extension and anti-tilt buffer. Lose barrels if not checked regularly.

    So to summarize what I've said in the past, If Eugene Stoner wanted the AR to be a 'gas piston' design he would have made it that way from the get go. Trying to make the AR15 platform a piston gun is like Chevrolet back in the day trying to make a good diesel engine out of the small block 350 (5.7L) engines ...it didn't turn out to well.
    Were these all your own personal guns or a mix of your guns and other peoples guns? What kind of round counts are we looking at also?

  8. #28
    Join Date
    Jun 2006
    Location
    NoVA
    Posts
    10,780
    Feedback Score
    17 (100%)
    Quote Originally Posted by LRB45 View Post
    Were these all your own personal guns or a mix of your guns and other peoples guns? What kind of round counts are we looking at also?
    Both...guns I've seen, worked on, shot, owned, T&E'd. Some as little at 1-2K rounds on them some as much as 25K rounds.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  9. #29
    Join Date
    Feb 2011
    Posts
    36
    Feedback Score
    0
    Quote Originally Posted by Robb Jensen View Post
    Yes:

    HK...cracked upper receivers when shot hard suppressed. Firing pin safety failures. Broken bolts.

    POF...highly worn receiver extensions which caused erratic bolt velocity which was causing failure to eject, failure to feed etc whenever the bolt carrier would get caught in the trough cause by carrier tilt. Cracked bolt, cracked log at top of bolt. Large amount of finish wear/gouging caused by front-top of bolt carrier dragging along the receiver bore as the carrier tilt. A temp fix is a new receiver extension and new upper receiver (two things that don't really wear out in DI guns by the way). One particular POF I've seen will not run on this one particular AR lower but on that same AR lower all DI uppers (7 different ones) worked just fine. Corrosive pitting of the gas piston and op rod. Broken bolt lug which got between the carrier and upper receiver and ruined the upper receiver which required a new receiver and new bolt.

    early ARES....bent op rod in less than 600 rounds on full auto on a 11.5" upper, due to spigot coming lose after the gas tube roll pin 'exited stage left'.

    LWRC...I've thus far fixed 4 lose barrel nuts, replaced heavy worn receiver extensions with this wear causing unusual stoppages (fixed with a new extension and anti-tilt buffer). Early ones had carrier keys coming lose before they key was integral to the carrier. On two early one I replaced two broken bolts (before Matech).

    PWS...lose gas block (2nd gen after moving away from a pinned gas block to a set screw gas block). Newer pinned Diablo style is much better. 1st gen I had the piston (which is attached to the carrier) came lose but I caught it before it caused stoppages.

    LMT...highly worn receiver extensions from carrier tilt causing unusual stoppages fixed with a new receiver extension and anti-tilt buffer. Lose barrels if not checked regularly.

    So to summarize what I've said in the past, If Eugene Stoner wanted the AR to be a 'gas piston' design he would have made it that way from the get go. Trying to make the AR15 platform a piston gun is like Chevrolet back in the day trying to make a good diesel engine out of the small block 350 (5.7L) engines ...it didn't turn out to well.
    +1 on the junky chevy diesels.Oh and trying to make the AR platform something it was never meant to be. People will never stop trying though.
    Whoever said the pen is mightier then the sword
    obviously never encountered automatic weapons.-MacArthur

  10. #30
    Join Date
    Feb 2009
    Location
    Texas
    Posts
    1,625
    Feedback Score
    16 (100%)
    Robb has also shot and evaluated the Ruger piston AR, which experienced a great deal of carrier tilt and associated wear in the first 1,000 rds.

    "Addressing the problem of shootings by ban or confiscation of non-criminal's guns is like addressing the problem of rape by chopping off the Johnson of everyone who DIDN't rape anyone while not only leaving the rapists' equipment intact, but giving them free viagra to boot." --Me

Page 3 of 9 FirstFirst 12345 ... LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •