Posted: 1/22/2017 2:31:24 PM EDT
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Hi all I built an ar 10 last year all top parts went to shoot it not cycling properly and brass damage at the base
I have had head space checked it is good has a matched barrel and bolt from mega arms I have an adjustable gas block now open all the way and still throwing brass forward toward barrel end and all the brass has a round mark next to the primer like it was shot with a BB gun some are deeper then others I have a JP full mass carrier with a carbine buffer and spring The gas block is an SLR .750 ADJ BLOCK I would love to get this straight any help would be great thank you Fred |
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You got a problem with the chamber or headspace. Opening the gas block all the way is just forcing your carrier back despite the issue which is ripping the rim off your brass during the forced extraction.
Are your rounds chambering without issue or do touch have to use the forward assist. Post pics of the extracted brass... |
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You built a rifle. Good for you.
Barrel length? Gas system length? What ammo did you shoot? I. Started with the gas block open two full clicks it expanded the case and it was stuck in chamber had to beat the charge Handel to get brass out and release the bolt and carrier |
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What ammo are you using? Your description is a perfect example of reloads that are:
1. Too hot. Too much powder or too fast a burning rate for your bullet. 2. Cases that were not resized enough. The die needs to be turned down more to bump the shoulder a few thousandths more back. I have very heavy buffers (Slash's) in my AR-10's and they have been totally reliable so far. Both have Noveske barrels. I have owned AR-15's with carbine gas systems that would rip the rims off the cases. They needed heavier buffers to get them to stop. Shorter gas systems tap more gas and they tap it quicker in the shooting cycle. The case hasn't had time to contract and now the rifle is trying to yank it out of the chamber. Can you load your ammo and eject it easily when it hasn't been fired? If not the ammo headspace is too long for your chamber headspace. If the ammo is fine run a heavier buffer and a lower gas setting on your gas block. |
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Need the following information:
Barrel length Gas system length Extension tube length (buffer tube) Recoil spring used Buffer used, length and weight Magazines Ammo Sounds like you are cycling really fast, which is often CLGS or MLGS .308 with too large of a port, wrong buffer and spring, and/wrong buffer and extension tube. These guns are best done under one roof when it comes to engineering, designing, specifying parts, and testing. Mixing and matching is a sure way to have an unreliable AR10-type build in many cases. A lot of the few samples out there that seem to run at first are actually beating themselves up with peening into the lower without the owner even knowing it. |
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OK barrel 22 in
Standard rifle length gas system Pa 10 standard carbine length buffer and spring Mag pul mags I had a rifle length spring and buffer in at first but took it to a gun smith after the very first round got stuck he polished the chamber and said I had the wrong buffer and spring The rounds im using are stock hornady 140 gr match bullets store bought |
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Quoted:
OK barrel 22 in Standard rifle length gas system Pa 10 standard carbine length buffer and spring Mag pul mags I had a rifle length spring and buffer in at first but took it to a gun smith after the very first round got stuck he polished the chamber and said I had the wrong buffer and spring The rounds im using are stock hornady 140 gr match bullets store bought This is like pulling teeth. 1) What brand upper & lower? 2) 140gr... So, is it 7mm-08 or 6.5CM? 3) BTW, PA10 ain't Top Parts to anything 4) Get specific/technical with LRRPF52. He's a Jedi Master at this stuff. Best to you. |
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OK again this is a 6.5 crmore
My original buffer and spring before the gunsmith I used to polish the chamber switched it on me was a Vltor A5-3 because I have a 7 position Vltor buffer tube and Jp ar 10 spring He told me that was the wrong one and switched it to the pa 10 buffer and a carbine length spring So now I confused to with spring and buffer for the Gun and the specific buffer tube I am running which is the Vltor Again the 8 rounds I shot over the weekend 6 single shots all flew out but flew forward away from me basically about 11 o'clock I shot two rounds with another round in mag and the gun did not throw the round out and double stacked the bullets Fred |
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Did the smith know that you have Vltor A5?
Normally you can use AR15 carbine length buffers with that tube in the AR10. If the BCG was not engineered/designed by the right people, you can still run into problems with a "correct" set-up because of BCG rail length on the bottom rails, but I'm not sure that's your problem. Would need to see the whole system laid out and firing to know what's happening here. With it being 6.5 Creedmoor and a RLGS, your port pressure is going to be much higher than the AR10 was ever meant to handle. That will drive your cyclic rate very fast, and usually push empties out forward of the gun, especially when shooting 140gr. You need to choke your gas and use a heavier buffer. Unfortunately, because the port is RLGS, you will see early port erosion, especially as you choke the gas with adjustable blocks. Savage made a much better adjustable gas system that allows port flow without choke, and they also placed it in ELGS rather than RLGS. |
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SO I am going to put the Vltor A 5 -3 buffer and that heavier spring back In and tune down the gas port to half and start there see what happens with the cycle rate
I agree it is cycling to fast and throwing the shells forward I dont mind spending money on the right parts to get this thing working properly I thank every body for there input |
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Quoted:
SO I am going to put the Vltor A 5 -3 buffer and that heavier spring back In and tune down the gas port to half and start there see what happens with the cycle rate I agree it is cycling to fast and throwing the shells forward I dont mind spending money on the right parts to get this thing working properly I thank every body for there input The VLTOR A5 buffers are meant for use in the AR15 and are slightly longer than a carbine buffer. This will not work with an AR10 BCG, as it doesn't allow enough rearward travel of the BCG. You need an AR15 carbine-length buffer with as much weight as you can get, at least an H3. |