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Posted: 1/14/2017 1:44:06 PM EDT
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I have a complete 7.62x51 PSA setup upper, lower, bolt group only non PSA parts are Heavy buffer & spring and Magpul PRS® Precision-Adjustable Stock, PMAG 10 LR/SR plastic mag (**edit **originally wrote Magpul Mag). I fired my rifle for first time it wont feed the second round. It fires a sigle shot fine and bolt hold open catch is functioning properly.
My first question how wet should the action area be especially on a new gun? It wasn't wet, just lubed. Will going back to a stock buffer allow it to feed better? 
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Brand new rifles and builds should be soaking wet during initial testing. So wet, after a few shots, oil oozes from every orifice.
It's a pain if you're bothered by oily, grimy hands. But necessary to insure pepper function and break in. Lots say no break in period needed, but that's bull. They are new parts that need to work together. EVERYTHING mechanical needs a break in period UNLESS it's so finely and precisely machined to exacting tolerances. Which, we all know, these rifles are not. Your heavy buffer should be fine as long as its an AR10 rifle buffer, which it must be if your bolt is locking back correctly. |
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Quoted:
Brand new rifles and builds should be soaking wet during initial testing. So wet, after a few shots, oil oozes from every orifice. It's a pain if you're bothered by oily, grimy hands. But necessary to insure pepper function and break in. Lots say no break in period needed, but that's bull. They are new parts that need to work together. EVERYTHING mechanical needs a break in period UNLESS it's so finely and precisely machined to exacting tolerances. Which, we all know, these rifles are not. Your heavy buffer should be fine as long as its an AR10 rifle buffer, which it must be if your bolt is locking back correctly. Thanks, will lube her up so she is dripping wet then I will runs many rounds through her..... |
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Out of curiosity, what magazines are you using with your rifle?
Don't be afraid to over lube the rifle. Unless you are using the rifle in very very extreme climates/conditions, extra lube will not hurt a thing. I bought all my components directly from PSA. I built the lower and bought a complete 20" upper and am using the 308 rifle buffer and spring from PSA also. I have two PMag magazines and haven't had any problems with my rifle. 
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I'm going to say you need a heavier buffer spring. I had the same issues with my AR-10 build, and I expected that as I had a light AR-15 carbine spring like my brother who had the same issues before me. He recommended the David Tubbs spring and I figured I give the light 15 spring a try first. No go. It didn't feed well, so I got the Tubbs spring and have had no issues since. FYI, my AR-10 has a carbine stock and a heavier 4.4oz buffer from CTD. There are numerous heavy springs out there I think, but my only experience is with Tubbs. It was about $30.
The AR-10 bolt is much heavier, of course, and it needs a heavier spring to push it back forward with enough force to strip the next round off the mag and send it home properly. As far as lubrication goes, I drench my bolt in motor oil and let it drain off over-night. I work it by hand a lot and blow out with air and wipe down before shooting the first time. Motor oil is a good cheap product for guns in basic mechanical applications. It has good staying power. Don't use it in the cold. John |
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Quoted:
Out of curiosity, what magazines are you using with your rifle? Don't be afraid to over lube the rifle. Unless you are using the rifle in very very extreme climates/conditions, extra lube will not hurt a thing. I bought all my components directly from PSA. I built the lower and bought a complete 20" upper and am using the 308 rifle buffer and spring from PSA also. I have two PMag magazines and haven't had any problems with my rifle. http://i577.photobucket.com/albums/ss215/12Bravo10/PA10_zps6qfk19kx.jpg I am using a 10 round PMAG LR/SR, mistakenly wrote Magpul in my post. I did have to clearance the mag slightly, in back side, to allow it to go up into the rifle so mag catch would lock. Quoted:
I'm going to say you need a heavier buffer spring. I had the same issues with my AR-10 build, and I expected that as I had a light AR-15 carbine spring like my brother who had the same issues before me. He recommended the David Tubbs spring and I figured I give the light 15 spring a try first. No go. It didn't feed well, so I got the Tubbs spring and have had no issues since. FYI, my AR-10 has a carbine stock and a heavier 4.4oz buffer from CTD. There are numerous heavy springs out there I think, but my only experience is with Tubbs. It was about $30. The AR-10 bolt is much heavier, of course, and it needs a heavier spring to push it back forward with enough force to strip the next round off the mag and send it home properly. As far as lubrication goes, I drench my bolt in motor oil and let it drain off over-night. I work it by hand a lot and blow out with air and wipe down before shooting the first time. Motor oil is a good cheap product for guns in basic mechanical applications. It has good staying power. Don't use it in the cold. John I have Slash’s XH rifle buffer and Spring, I think my problem is lubrication. I wanted to rule out something I may have missed in my build. I have done a 9mm pistol and rifle and a 45 pistol and all is good. With this caliber I didn’t want over look something. I will soak the bolt as you recommended. |
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I'd be willing to bet it's the magazine not presenting the next round properly because the magazine is not positioned correctly.
I purchased a PA10 lower that wasn't machined properly to accept Magpul magazines. I wasn't going to modify all my mags so I ditched the lower...and the upper...and put the parts on an Aero M5 set. Zero problems later. Stock buffer spring. I will also suggest oiling up the gun and hand cycling the action a few hundred times. Seems to break things in well. I'd not worry about the buffer spring at this point. It might also be that the extractor is not catching the round, especially if the problem is common on one side of the magazine versus the other. You might pull the extractor, remove the second o-ring and try again. Good luck! |
| I just got back from range. Still having problems but I think I can narrow it down. So I ran it wet, what is happening it can feed the 2nd round its just that the round and bolt dont seat fully in the chamber. Pressing the forward assist isn't enough. If I pull the charging handle back about and inch or so let it go and it will seat the bolt and the round. What has me puzzled is the gun works perfect to feed the first round. I can pull handle back and let her rip chambers perfectly, also can chamber 2nd and 3rd round this way (manually). Additionally, with bolt open I can insert mag just release the bolt with the bolt hold open catch (??) and that round is chambered fine. |
| I bet it is a tight extractor. Using the handle it will chamber it properly but using the FA it won't. Mine did the same thing. My first issue with my pa10 was the bad headspace/chamber deal. And it wouldn't even chamber the first round. At least you don't have that problem. After psa fixed my pa10 then it did what yours did. Removed a o ring and installed a ar15 extractor spring. It's been flawless since. |
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Ok will take the bolt apart and see what is in there. BTW I did remove the heavy buffer before shooting it this time.
I am still a little confused as to an alternative mag I would like to get a steel one. I have this one: Magpul PMAG Gen 3 DPMS LR308/SR-25 Pattern AR 308 Magazine So do I use an SR 25 type; ASC SR-25 10 Round Magazine .308/7.62 Or an LR 308; ProMag, DPMS LR-308 Magazine, .308 Winchester/7.62 NATO Or this one ProMag, DPMS LR-308/SR-25 Magazine which is both LR308 and SR-25? |
| Last night I pulled the bolt apart and there was one (1) O ring with the extractor spring so I removed the O ring and put spring back in and reassembled it. Unfortunately to get to the range takes some doing, hopefully will get there by next weekend. Will update then. Thanks for all help so far. |
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Last night I pulled the bolt apart and there was one (1) O ring with the extractor spring so I removed the O ring and put spring back in and reassembled it. Unfortunately to get to the range takes some doing, hopefully will get there by next weekend. Will update then. Thanks for all help so far. If it still malfunctions your next step should be 1 o-ring with a ar15 extractor spring. That's what my pa10 needed. |
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There is so much conjecture in this thread, without having a full picture of what is going on.
You start to see very quickly how bad advice can be thrown all over the place. OP: You said you made modifications to the magazine. What is it that inspired you to do that, and do you have pictures of before and after? Magpul is the maker of the PMAG-same company. |
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OP: You said you made modifications to the magazine. What is it that inspired you to do that, and do you have pictures of before and after? Magpul is the maker of the PMAG-same company. All I did was take a small amount of material off the lower back end of mag, there was a beveled up plastic area that I removed with a dremel. Prior to the mod the mag wouldn't go in far enough to catch, the mag was tight against the lower. I slowly removed material until it would slide in and engage securely. 
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| After seeing how you modified the magazine, I'm thinking that it still might be hitting the bottom of the magwell and not fully seated or seated and a slightly off angle causing the feeding issue.. A different magazine (without the lip around it) would rule out any out of spec machining on the lower. |
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Quoted:
After seeing how you modified the magazine, I'm thinking that it still might be hitting the bottom of the magwell and not fully seated or seated and a slightly off angle causing the feeding issue.. A different magazine (without the lip around it) would rule out any out of spec machining on the lower. That is what I am thinking |
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