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  • #16
    Originally posted by wheezengeezer View Post
    Standard weight 12.5 oz full auto bolt. Rifle length gas sys. 16.5 inch voodoo lightweight barrel. .098 dia gas hole in barrel. I think a standard buffer spring. Will try another spring first. Then maybe drill out gas hole a little,then try a lighter bolt.
    The gas system is too long for the barrel length.
    2 things matter to drive an Autoloader, gas Pressure is only 1 of them.
    People ignore Dwell Time, the inches of barrel past the gas port.

    The rifle system gives the system 20-25,000 psi gas and 8" of dwell time (20" barrel), and in standard build, are overgassed.

    You have A Bad Idea, 20,000psi gas for a 4" dwell time.

    A 16" carbine system has 35,000 psi gas for 9" of dwell time (7.5" military), and is badly overgassed.

    A 16" barrel MIGHT be ok with a mid-length system, BUT, the rifle system IMO should be in nothing shorter than 18".

    I run an 18" .308 Rifle and a 16" .223 Carbine, zero issues at all, standard parts.

    Try a lighter buffer before the lighter BCG.

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    • #17
      First I will try it on a different lower that works well with a 16 inch MID barrel with a hole .065 dia. Next disassemble BCG, clean and inspect gas seals,extractor and spring. Then I will look into reducing buffer weight. I already realized the barrel has an extremely short dwell time. This thing has never worked right.
      I was raised in the 50\'s on jackrabbits and gunpowder.salt and pepper wooda made\'em taste better

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      • #18
        You will have to re-balance the gun's drive energy requirements with either more gas pressure (you can't), more dwell time (suppressor), or lower the drive energy requirements (lighter reciprocating components, weaker springs).

        JP's Silent Captive Spring has a Tuning Spring Kit available for it,,, 5 springs, 1 standard, 2 stronger, 2 weaker (IIRC). you MAY have to go there to get spring power down enough.

        The AR design was not designed for an extremely short dwell time like the Garrand and M-14 were.
        The only reason I can imagine making a 16.5" barrel and then drilling it for a rifle-length gas system is to suppress it, because otherwise it's going to be hell to get to run.

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        • #19
          Barrels are so cheap now, I'd just switch barrel, either 16" carbine or mid gas system, are dime a dozen, gas tube few bucks more.
          Columbia Falls, MT
          If we don’t speak out against the infringements of today, it will weaken our ability to stop the next infringements.
          Since it took 26th Amendment to change voting age, expanding rights under 14th Amendment. Why doesn't same requirement, to restrict rights, extend to 2nd Amendment?


          NRA Benefactor Life, NRA Ring of Freedom, NRA-ILA Partner in Freedom, GOA Patriot, SAF, Oath Keepers

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          • #20
            True.
            Also, you go to making closing springs weaker and making reciprocating parts lighter, at some point you run out of energy to strip and feed ammo from magazines, which operates from inertia.

            If you want a 16" barrel, Carbine system and adjustable gas block.

            Save the 16" rifle system for a can.
            ​​​​​​

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            • #21
              Gas rings are good,plenty of tension. I am considering cutting the bolt to semi auto configuration,or picking one up if I can find one. I will tell my friend he should just buy another upper and save this one back.
              I was raised in the 50\'s on jackrabbits and gunpowder.salt and pepper wooda made\'em taste better

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              • #22
                I am going to say DO NOT remove the lower firing pin shroud from that carrier, you invite further problems.
                Hammer Snag jam.
                Also near elimination of firing pin retaining pin life, constantly bending.

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                • #23
                  I agree, don't cut the bolt carrier, nothing but trouble. The point I was trying to make with barrel comment, instead of chasing your tail, with problem barrel, replace it, changing barrel is easy, if you want rifle length gas system, get a 20" barrel it was designed for.

                  Columbia Falls, MT
                  If we don’t speak out against the infringements of today, it will weaken our ability to stop the next infringements.
                  Since it took 26th Amendment to change voting age, expanding rights under 14th Amendment. Why doesn't same requirement, to restrict rights, extend to 2nd Amendment?


                  NRA Benefactor Life, NRA Ring of Freedom, NRA-ILA Partner in Freedom, GOA Patriot, SAF, Oath Keepers

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                  • #24
                    I would change the upper assembly. Not sure what my friend can afford. Dropping the carrier weight by .9 oz to the weight of a semi auto would be inexpensive and reversable. Dont want to speed up the gas lag time because chamber pressure needs to drop before it unlocks. Dont have a can to change dwell time.. Buffer is 2.9 oz which is correct. Am not going to remove any weight from it. If my local has a lighter buffer I may try one. If not the origional ar15 config without exposed firing pin is what I had in mind.
                    I was raised in the 50\'s on jackrabbits and gunpowder.salt and pepper wooda made\'em taste better

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                    • #25
                      There is plenty of gas to move things around. Your problem it the timing of it.

                      With a heavier buffer the reciprocating mass takes a millisecond longer to overcome that extra weight and spring tension allowing the bullet more time to scoot out of the barrel “dwell time”.

                      An adjustable gas block does not make any more gas available to you. It is a way of squeezing down the size of the gas port. After you have drilled out the hole on your barrel and become over gassed, you will need one to reduce it back to where you have only the gas you need.
                      Endeavor to persevere.

                      Call sign: Limp Wrist

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                      • #26
                        Yep,, adjustable gas blocks (AGB's) are for throttling down too much gas, they won't create more anywhere.

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                        • #27
                          Originally posted by RobertMT View Post
                          Barrels are so cheap now, I'd just switch barrel, either 16" carbine or mid gas system
                          They are cheap enough to have too many And barrels are real easy to swap with minimal hardware and the tools most guys have on hand.


                          Experience is what you get, when you don\'t get what you want ;-)

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                          • #28
                            Swapped the BCG from a full auto to a semi. The weight reduction worked well. Throws them out about 4 o'clock.
                            I was raised in the 50\'s on jackrabbits and gunpowder.salt and pepper wooda made\'em taste better

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