AR10 malfuction help

Discussion in 'AR15/10 Rifles' started by scottyd2506, Aug 21, 2012.

  1. scottyd2506

    scottyd2506 Well-Known Member

    Messages:
    150
    Joined:
    Aug 22, 2009
    I have an Armalite AR-10 308 24 inch SS BBL that I bought used, it shoots nice, but the last time I went out it was jamming.

    I'll try to describe the details.

    What it was doing is not extracting the spend 308 case and jammed it back into the action, smashing the case mouth.

    I took it apart cleaned the Bolt carrier all up oiled it and action. Took out the Buffer spring cleaned and and lightly oiled it.. and now it works.

    BUT
    I am not sure ehat was wrong because it did not seem dirty, I cleaned and oiled the BCG and action 30 rounds before the jam in the 1st place,

    It did this will all the magazines 10's 20's 25's with only 3 to10 rounds in them

    A friend of mine who was with me with his AR-15 says he thinks the Buffer spring is too heavy. It has a Tronstone stock if anyone has ever heard of it.

    He thinks it has a heavy duty spring in it to reduce recoil the precious owner might have put in. but since he is used to Ar-15 with a much lighter buffer spring who is to say what heavy is to him.

    he could be right, as it seems to jam when oil is not drenched on parts, and I think maybe the buffer spring is a heavy one and everything has t o be perfectly oiled up for the cases to extract, any slight friction and the action does not go far back enough.
    I am a Bolt guy, so I am new to the AR platform and this is just my mechanical guess. and I could be way off here. Any help from you pros would be great.

    I am shooting right now 168 SMK, 24.0 H4895. Not a max load, but not a light load either
    my plan is to shoot 125 to 150's once my 168 are used up


    I am worried it will not function with 125's or even 150's even when oiled up.

    does AR10's need to be drenched in oil to function?

    does this seem like a gas port issue?.

    thanks
     
  2. tatersalad

    tatersalad Member

    Messages:
    22
    Joined:
    Jul 27, 2012
    It could be a gas issue, but I'd probably try a standard buffer spring first. You might also want to check to make sure it has a standard weight buffer as well.
     

  3. Kevin Thomas

    Kevin Thomas Well-Known Member

    Messages:
    1,256
    Joined:
    Feb 16, 2009
    I'm assuming that's 42.0 grains, not 24.0? At 24.0 grains, I'd be surprised you'd be able the gun to function at all.
     
  4. scottyd2506

    scottyd2506 Well-Known Member

    Messages:
    150
    Joined:
    Aug 22, 2009

    Sorry about that, I'm thinking 223, same powder (H4895) and 42.0 grains is what I use
     
    Last edited: Aug 21, 2012
  5. scottyd2506

    scottyd2506 Well-Known Member

    Messages:
    150
    Joined:
    Aug 22, 2009
    forgot to maintain earlier, the rifle throws brass at 2 oclock.

    how can I tell what is standard weight? (buffer)
     
  6. Kevin Thomas

    Kevin Thomas Well-Known Member

    Messages:
    1,256
    Joined:
    Feb 16, 2009
    Scottyd,

    43.0 grains isn't a light load, either. When the 308 was the "standard" cartrdige used for across the course competition, 41.0-42.0 grains was what EVERYONE was using. No such thing as load development for an M14 or M1A. You stuck 41.5 (or so) grains of 4895 in a case, topped it off with a 168 and went to the range. If the gun didn't shoot it, you had a gun problem, simple as that. Might try backing it off a grain just to see, but I doubt that's the problem here. In the process of building up an AR-10 right now for long range competition, but it will be a while before that's up and running. We'll be geared towards the 185s for 1,000 yard shoots, but other than that we might be able to see what else is going on here.
     
  7. ICANHITHIMMAN

    ICANHITHIMMAN Well-Known Member

    Messages:
    4,380
    Joined:
    Jan 31, 2008
    Check the torque on the gas key. Call aramilite and ask what buffer should be in the rifle and what the recoil spring should measure when you pull it out of the stock.

    There is no such thing as to much oil in an ar and don't oil the buffer spring.
     
  8. scottyd2506

    scottyd2506 Well-Known Member

    Messages:
    150
    Joined:
    Aug 22, 2009
    I corrected it after you posted, 42.0 is what I used with H-4895. Not sure why I posted 43.0 probably because I had went up to 43.0, and backed off to 42.

    I'm sorry to mislead you, I'm more concentrating on fixing the problem than remembering the charge weights.

    I do weigh each charge.

    What king of Ar10 platform you building? curious.

    thanks
     
  9. load

    load Well-Known Member

    Messages:
    366
    Joined:
    Jan 18, 2010
    it maybe gas rings. try this. remove the bolt carrier, take out the cam and firing pin, then extend the bolt head out. place the bolt head/carrier on a table with the bolt head facing down. if gravity causes the carrier to slide down bolt head then the rings are garbage and need to be replaced. direct impingement is simply a piston system inside the action,the bolt carrier is the cylinder and the bolt head is the piston the rings in 308s can go bad rather quickly.gun)
     
  10. scottyd2506

    scottyd2506 Well-Known Member

    Messages:
    150
    Joined:
    Aug 22, 2009

    Thank you, I will try this. know any place that sells replacements?
     
  11. Kevin Thomas

    Kevin Thomas Well-Known Member

    Messages:
    1,256
    Joined:
    Feb 16, 2009
    Scottyd,

    no apoloigies needed here, as I didn't think you were "misleading me". Hey, we all make typos, myself included, and I just wanted to make sure we were clear and on the same sheet of music. Regardless, I doubt this is a charge weight issue if you're anywhere near the ballpark numbers we'd discussed. Something else likely going on here. Others have mentioned the gas rings, the carrier key being staked properly and several other potential problem spots; all good comments and certainly worth a look. No one has asked about your reloading practices yet, and I'd like to know a bit more about that. What type of sizing are you using? Full Length, at least? Small Base may be a worthwhile consideration, if you're not already using it. Many folks miss the fact that SB sizing not only makes the rounds chamber more positively, but it also allows them to extract a bit more easily, too. Might be worth a try, if you're not already doing so. As I've said repeatedly, gas guns are a whole different world, and things that aren't an issue at all for a bolt gun, suddenly become real problems when the ammo is stuffed into a gas gun.

    Our coach wants us (Lewis and Clark Shooters Association, the team I shoot with) to field a 1,000 yard Service Rifle team for Perry next year. To that end, we're building clones of the M110s the Army has been using. USAMU's posted some very respectable scores with these already, so the platform is a proven design. So well, in fact that they've abandoned their M16s altogether for the long range matches, and are now using the M110s. Oddly enough, they'd gotten rid of all their M14s, and just come back to the position that even with high velocity 80 and even 90 grains bullets, the 5.56mm just can't match what you can do with a 30 cal. round at distance. So that's where the M110 idea came from. As for what we're building, they have to conform to the NRA regs for a competitive Service Rifle; standard stock and pistol grip, a floated fore end with four sided Picatinny rail, and a flat top (A4 configuration) upper fitted with detachable carrying handle rear sights, and a gas block with a detachable front sight tower. In short, just what the USAMU has been using. As far as the optional stuff, a Gisselle trigger, weighted stock, a Satern cut rifled barrel and Satern pinned/modified rear sights. Like I said, only so much you can to to a Service Rifle and stay within the class. Virtually all mods are internal. Sort of like a NASCAR stock car, they have to retain the basic outward appearance of the factory item. Just very different under the hood. Be a while before we're up and running on these, just a collection of parts right now. The barrels are being drilled this week, and will be getting rifled within a week or two after that. Long slow process (or so it seems), but it's a long way off to Perry right now.
     
  12. scottyd2506

    scottyd2506 Well-Known Member

    Messages:
    150
    Joined:
    Aug 22, 2009

    for most my bolt guns I neck size, but I full length for the auto. They are just normal cheap FL Lee Dies, I am new into the auto world so small base is something I know little about, but I will look into that for sure.

    might make an order for small base dies with the gas rings

    thanks for the info
     
  13. nitrousmudbogger

    nitrousmudbogger Well-Known Member

    Messages:
    216
    Joined:
    Feb 6, 2011
    What kind of brass are you running through it? Have you tried a factory load? It sounds like it is short stroking and once oiled a lot it gets far enough to get the empties out and snag a new one. If it is relatively hard to pull back it is a 308 spring. Not much else available out there for 308's. A few other things to try would be to clean the gas port in the barrel and anything else that looks carbon like. If someone cleaned the gun without taking the gas block off possible corosion and gunk is plugging up the tube or block? Let me know, I can keep coming up with ideas, I deal with it every day
     
  14. scottyd2506

    scottyd2506 Well-Known Member

    Messages:
    150
    Joined:
    Aug 22, 2009

    I will use the info, not used factory ammo yet. I bought brass and reloaded--
    I had H4895 powder (used for 223), and 2 boxes of 150 and 168 matchkings I had extra for my 300 win mag, large Rifle primmer's I use for my 25-06. So all I needed was brass and dies.

    I took the new brass and FL re sized them, oiled gun up took to range and never had a problem, but the 2nd time (a week later) I went out it started to jam all the time. I guess I did not put enough oil on the BCG as it seemed dry to barely having oil on it..
    took the gun home, spayed cleaner through gas ports and action.. oiled it up good and it worked flawlwess. my issue is. I'd still like the gun to at least work when it is not drenched in oil.
    Heck if all "heck breaks lose", what would I tell my attackers ??
    "wait a minute, I need to oil the gun 1st before I can defend myself from you!!" LOL

    I bought it used, but the guy who had it put only like 100 rounds through it at the range. So maybe it is not broke in.
    I will use ur advice though, and take off gas block and clean there.
    thank you