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Posted: 3/22/2015 9:25:01 PM EDT
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Hello,
Having built a couple AR-15's, I decided to try and build my first AR-10 because it shouldn't be that much different. Right? (I can hear you chuckling already) PSA PA-10 Lower (SR-25 Type Magazines) DPMS Upper PMag 7.62x51mm Magazine WES (Weapon Enhancement Systems) 308 BCG Have not fired any rounds yet and I found my first problem or two. #1 When the bolt is retracted back and an empty PMag is installed, the bolt sticks on the PMag follower as it's moving forward. The bolt catch is NOT holding it back, just the PMag follower. http://www.hunt101.com/data/500/medium/BoltStick.jpg Thanks for any advice #2 When snap caps are seated in the magazine and the bolt is cycled, it does feed a .308 snap cap into place, but the bolt does not go fully forward. I have not installed the forward assist yet, so I'm not even sure if it can be fully seated home. (pic is upside down, sorry) http://www.hunt101.com/data/500/medium/FwdAssist.jpg |
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Does the bolt go far enough back to catch on the bolt catch? If not what buffer, and extension are you using. The PSA has a proprietary tube so you can use standard ar15 length buffers. If you use thier buffer in a standard tube the bolt won't go back far enough. If you got them from PSA it is a possibility that they sent you the wrong one. It should e 3/4 longer than an ar15 tube if you have one to compare. Are you using the lpk or at least the upgrade kit from PSA? There are some proprietary parts on the PSA lower such as the pivot and takedown pin and bolt catch. Also AR10 mags sit higher than ar15 mags and the difference in receivers may be making it worse. When cycling my Maten by hand I can feel the bolt going over the follower but not enough to hold I like in your pic. With the mag up higher it may be putting more friction on the bolt as its closing and stopping it from going into battery or with the bolt not going far enough back I may not have enough energy to go into battery. Have you checked the headspace? In my Maten when first put together the headspace checked out fine but wouldn't go into battery on a full mag. After some cleaning and lubing of the bolt and breaking it it goes in every time now. And as others have said there are some parts that don't interchange well, I would always recommending using an upper and lower reciever from the same manufacturer. Not saying it can't be done but you are asking for headaches.
If you want I can take some pics of my bolt to mag interface when I get home |
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Wow! Thanks for all the info and questions.
The buffer tube, spring, and buffer are not from PSA. They were purchased separately, don't know the manufacturer off the top of my head. The PSA lower I purchased is marketed as using all standard AR15 parts (not the takedown pins of course). Their previous generation lowers required a mix of AR10 and AR15 standardized parts. I do NOT have the headspace gages, but I should probably invest in that before a live round ever goes near this thing. I will check about the rearward travel of the bcg, because it is NOT catching on the bolt catch lever. |
| Can you point me in the direction of one of the "new" lowers? I just checked their website and the one listed tree says it uses ar15 FCGs wich is referring to the trigger disconnector hammer springs and pins, not the bolt catch and mag release. It's not that I don't believe you it's just that I want to make sure you got your info straight. The buffer and spring you are using, are they ar15, dpms lr308, or armalite ar10? An ar15 buffer is too long to allow te bolt to go far enough back and te spring is too weak to go into battery. The dpms uses an ar15 tube with shorter buffer and stronger spring. Armalite uses all different components and I am not familiar with them so I can't tell you what exactly the differences are. |
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And here are some pics. The first one is how far the bolt should go behind the catch when pulled all the way back and the second one is much the bolt face touches the mag follower. Thinking about it if you are using the wrong catch then there is a possibility the mag is going to far into the lower. Either that or it's just the difference in heights between dpms upper and PSA lower.
http://i292.photobucket.com/albums/mm29/S50b31/Mobile%20Uploads/image_zpsngqdlkch.jpg http://i292.photobucket.com/albums/mm29/S50b31/Mobile%20Uploads/image_zpsla9bq4kp.jpg |
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