thesniper101 Posted July 11, 2017 Report Share Posted July 11, 2017 hello everyone im new to the forum and also new to the 308 AR world, i just completed my first 308 rifle and needed some help. i will give a build rundown in case maybe some of the parts are incompatible. But my rifle is having the bolt stick a bit when closed on snapcaps. barrel/bolt- faxon 16" with headspaced faxon bolt Bolt carrier/spring- JP fmos carrier and JP silent capture 308 size receiver set- CMT 308 set gas tube/gas block- SLR adjustable gas block and mid length gas tube Stock- Magpul UBR handguard- SLR 13" all of my internal components are DPMS platform incase anyone is wondering so back to the sticking bolt. when operating the rifle without snapcaps it functions fine, the bolt goes in and out of the barrel extension smoothly. but when i loaded snapcaps up the bolt sticks a fair bit, I dont have to mortar the rifle but i do need to pull the charging handle fairly hard to get the round out. I have never fired the weapon and I just put it together an hour ago. could the gun just be tight from being brand new? maybe a tight chamber? should I take it to the range and attempt to shoot it and see if it just needs a break in? I have built many ar-15s but ive heard the 308 is a different animal. thanks for any and all info on the matter! Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 11, 2017 Report Share Posted July 11, 2017 1 hour ago, thesniper101 said: Bolt carrier/spring- JP fmos carrier and JP silent capture 308 size Stock- Magpul UBR Need more details on these two things, spwcifically. Well, all three. The UBR is a carbine-stock setup,with it's own built-in AR15 Carbine-lengthed receiver extension, with an internal depth of 7.000". - You sure those parts are compatible? Before I go look up the JP stuff? Quote Link to comment Share on other sites More sharing options...
thesniper101 Posted July 11, 2017 Author Report Share Posted July 11, 2017 I contacted JP the magpul UBR is okay to run with their 308 silent capture spring, their spring can be used in ar-15 length receiver extensions. also on their 308 rifles they run te UBR with the fmos and silent capture Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 11, 2017 Report Share Posted July 11, 2017 I'm seeing 6 different JP Full Mass carriers - which one do you have, specifically, by part number? Just trying to figure shiit out here. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 11, 2017 Report Share Posted July 11, 2017 Dear Sweet Baby Jesus, they have 4 different flavors of the SCS for an "AR-10," as they state... Which one of those things do you have? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 11, 2017 Report Share Posted July 11, 2017 Just trying to help here, please don't think I'm being a dick. Info is everything, and it's been general thus far, considering all the options with this JP stuff. Just so you know, one of my mottos is: Don't complicate shiit with complicated shiit. The JP-anything is complicated shiit... Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 11, 2017 Report Share Posted July 11, 2017 @survivalshop, hey brother - this is just ANOTHER reason I just run the Armalite AR-10 Carbine recoil system on collapsible stock Big ARs, and I don't have to fuk with it... Quote Link to comment Share on other sites More sharing options...
blue109 Posted July 11, 2017 Report Share Posted July 11, 2017 58 minutes ago, 98Z5V said: Dear Sweet Baby Jesus, they have 4 different flavors of the SCS for an "AR-10," as they state... Which one of those things do you have? That made my brain hurt. Quote Link to comment Share on other sites More sharing options...
thesniper101 Posted July 11, 2017 Author Report Share Posted July 11, 2017 the bolt carrier from JP part # is -JPBC-5 the spring part # is -JPSCS2-10 entering into this i already had jp parts for a few of my ar-15s and really liked their parts so i wanted my AR-10 to use their components. sorry if its a little complicated, and I dont think you're being a dick, i appreciate the thoroughness. I MIGHT have solved the issue... i tore the whole gun apart and looked over everything. all the parts worked smoothly until i took a look at the bolt, i pulled the extractor out and it had 2 crane O-rings. I read reports of that setup causing problems in some guns, so I removed one O-ring and the gun extracts smoothly and doesn't bind anymore. Quote Link to comment Share on other sites More sharing options...
DNP Posted July 11, 2017 Report Share Posted July 11, 2017 Is it well lubed? How does it handle a real round? Quote Link to comment Share on other sites More sharing options...
Doodle Posted July 11, 2017 Report Share Posted July 11, 2017 9 hours ago, thesniper101 said: so back to the sticking bolt. when operating the rifle without snapcaps it functions fine, the bolt goes in and out of the barrel extension smoothly. but when i loaded snapcaps up the bolt sticks a fair bit, I dont have to mortar the rifle but i do need to pull the charging handle fairly hard to get the round out. I would first blame the snap cap. The plastic may not be as slippery as brass in the chamber, may be oversized, and may be getting compressed/pinched when loaded into the chamber making it tough to pull out. If you're dropping the bolt release on it, it is getting driven home much harder than a typical pull back on the charging handle. As you said, it operates fine w/o the snap cap. Perhaps run a different snap cap, or better a spent piece of brass, and check the cycle. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 11, 2017 Report Share Posted July 11, 2017 (edited) 7 hours ago, 98Z5V said: @survivalshop, hey brother - this is just ANOTHER reason I just run the Armalite AR-10 Carbine recoil system on collapsible stock Big ARs, and I don't have to fuk with it... Even when using a UBR stock ?? 6 hours ago, thesniper101 said: the bolt carrier from JP part # is -JPBC-5 the spring part # is -JPSCS2-10 entering into this i already had jp parts for a few of my ar-15s and really liked their parts so i wanted my AR-10 to use their components. sorry if its a little complicated, and I dont think you're being a dick, i appreciate the thoroughness. I MIGHT have solved the issue... i tore the whole gun apart and looked over everything. all the parts worked smoothly until i took a look at the bolt, i pulled the extractor out and it had 2 crane O-rings. I read reports of that setup causing problems in some guns, so I removed one O-ring and the gun extracts smoothly and doesn't bind anymore. What Extractor spring system is in the Bolt ? Two ( one inside another ) like a DPMS Bolt ? Edited July 11, 2017 by survivalshop Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 11, 2017 Report Share Posted July 11, 2017 1 hour ago, survivalshop said: Even when using a UBR stock ?? If I wanted a UBR on a Big AR, I'd run the UBR 2, which is 7 5/8" internal depth - and I'd load it with Armalite AR-10 Carbine buffer and spring... Quote Link to comment Share on other sites More sharing options...
thesniper101 Posted July 11, 2017 Author Report Share Posted July 11, 2017 3 hours ago, Doodle said: I would first blame the snap cap. The plastic may not be as slippery as brass in the chamber, may be oversized, and may be getting compressed/pinched when loaded into the chamber making it tough to pull out. If you're dropping the bolt release on it, it is getting driven home much harder than a typical pull back on the charging handle. As you said, it operates fine w/o the snap cap. Perhaps run a different snap cap, or better a spent piece of brass, and check the cycle. When I worked at a local gun shop some of my bolt guns with tight chambers didn't agree with snap caps. I haven't loaded a real round yet because I haven't had time to take it to the range, I didn't want to load a live round at home and have that stuck in the rifle. Quote Link to comment Share on other sites More sharing options...
thesniper101 Posted July 11, 2017 Author Report Share Posted July 11, 2017 2 hours ago, survivalshop said: Even when using a UBR stock ?? What Extractor spring system is in the Bolt ? Two ( one inside another ) like a DPMS Bolt ? The bolt pattern is a dpms style, and when I removed the extractor I saw two O-rings one on top of another. But when I removed one of the O-rings it would function fine with snap caps. I think I need to go test fire it and see if it needs to be broken in or maybe the snap caps aren't agreeing with the chamber Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 11, 2017 Report Share Posted July 11, 2017 4 hours ago, thesniper101 said: The bolt pattern is a dpms style, and when I removed the extractor I saw two O-rings one on top of another. But when I removed one of the O-rings it would function fine with snap caps. I think I need to go test fire it and see if it needs to be broken in or maybe the snap caps aren't agreeing with the chamber No spring or springs of any sort ? I guess the new DPMS GII Extractor spring is not a spring , but made of Elastomer & they say it works fine & even have a kit for the LR 308AR , so two O-rings or one in your case may work . Quote Link to comment Share on other sites More sharing options...
survivalshop Posted July 11, 2017 Report Share Posted July 11, 2017 (edited) 5 hours ago, 98Z5V said: If I wanted a UBR on a Big AR, I'd run the UBR 2, which is 7 5/8" internal depth - and I'd load it with Armalite AR-10 Carbine buffer and spring... Geez , well go for it You would have to do something , because thats too long inside for a std DPMS 308AR Carbine spring & that would cause issues , anyway . You might get the BCG hitting the back of the Lower Receiver . Edited July 11, 2017 by survivalshop Quote Link to comment Share on other sites More sharing options...
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