usmc1974 Posted March 29, 2023 Share Posted March 29, 2023 (edited) I just got a new AR-10 with a 20 inch barrel it's mostly areo precision parts. the barrel I got off GunBroker it was not an expensive barrel. Now the problem is it will not chamber the rounds, they go into my case length gauge, perfect. they fall in and out it it. but they will not chamber in the gun. if I let the bolt go home real easy it does not go home all the way home as you can see in the picture. Edited March 29, 2023 by usmc1974 Link to comment Share on other sites More sharing options...
mpeltier Posted March 29, 2023 Share Posted March 29, 2023 (edited) Many moons ago when I got my first DPMS TAC20 it exhibited this characteristic. Didn't want to reliably chamber anything. They had some arm length disclaimer about just about any and all foreign made 7.62x51 not being any good for their chambers, but I ultimately found it was just really sharp points on the barrel extension in the vicinity of the machined feed ramp, where the bolt lugs run thru and then lock. It was very evident by some judicious scratches and gauges in the brass of rounds I tried to chamber. These burrs were just grabbing the soft brass and putting the breaks on. A small file and a little patience I had the barrel extension nicely smoothed out. That thing would chamber just about anything after that. Hope this helps. Edited March 29, 2023 by mpeltier Link to comment Share on other sites More sharing options...
kurtm Posted March 29, 2023 Share Posted March 29, 2023 You can't let the bolt go forward "real easy". The extractor, which is under spring tension, has to slip over the rim of the cartridge. This takes a bit of force like the bolt closing under full spring force or hitting the forward assist. You can't gently lower the bolt on an AR-10! Link to comment Share on other sites More sharing options...
usmc1974 Posted March 29, 2023 Author Share Posted March 29, 2023 1 minute ago, kurtm said: You can't let the bolt go forward "real easy". The extractor, which is under spring tension, has to slip over the rim of the cartridge. This takes a bit of force like the bolt closing under full spring force or hitting the forward assist. You can't gently lower the bolt on an AR-10! I am talking about without a round even in the gun... Link to comment Share on other sites More sharing options...
kurtm Posted March 29, 2023 Share Posted March 29, 2023 Ahhh, well two things then. Wrong gas tube IE. full length tube on a mid length barrel. Mid length on a carbine length barrel, etc. Wrong pattern bolt to extension. IE. DPMS/SR-25 style bolt and an Armalite style barrel extension or Vise versa. Link to comment Share on other sites More sharing options...
usmc1974 Posted March 29, 2023 Author Share Posted March 29, 2023 (edited) 34 minutes ago, mpeltier said: Many moons ago when I got my first DPMS TAC20 it exhibited this characteristic. Didn't want to reliably chamber anything. They had some arm length disclaimer about just about any and all foreign made 7.62x51 not being any good for their chambers, but I ultimately found it was just really sharp points on the barrel extension in the vicinity of the machined feed ramp, where the bolt lugs run thru and then lock. It was very evident by some judicious scratches and gauges in the brass of rounds I tried to chamber. These burrs were just grabbing the soft brass and putting the breaks on. A small file and a little patience I had the barrel extension nicely smoothed out. That thing would chamber just about anything after that. Hope this helps. You might have been right all of the brass has these two little marks on the neck. I hope you can see them in the picture Edited March 29, 2023 by usmc1974 Link to comment Share on other sites More sharing options...
kurtm Posted March 29, 2023 Share Posted March 29, 2023 Marks on the neck are from extraction, going past locking lug cuts. Gas tube should be in this range as pictured DPMS AR-10 Link to comment Share on other sites More sharing options...
usmc1974 Posted March 29, 2023 Author Share Posted March 29, 2023 10 minutes ago, kurtm said: Marks on the neck are from extraction, going past locking lug cuts. Gas tube should be in this range as pictured DPMS AR-10 Gas tube is correct Link to comment Share on other sites More sharing options...
usmc1974 Posted March 30, 2023 Author Share Posted March 30, 2023 (edited) 19 hours ago, kurtm said: Marks on the neck are from extraction, going past locking lug cuts. Gas tube should be in this range as pictured DPMS AR-10 Gas tube is correct Rifle length Gas system riflelength gas tube. I took it to a gun smith and he believed it was just a tight chamber and I should try 308 small base dies. So I will give that a try. But you guys are great. Edited March 30, 2023 by usmc1974 Link to comment Share on other sites More sharing options...
TonytheTiger Posted March 30, 2023 Share Posted March 30, 2023 If it was a tight chamber bolt would still close fine on an empty chamber. Link to comment Share on other sites More sharing options...
Rookie Posted March 30, 2023 Share Posted March 30, 2023 When my bolt (AR10 or AR15)won't fully close on an empty chamber, under spring force alone... I know that it is time to add lubricant to the bolt. Did you (USMC 1974) drop a round into the chamber of this rifle to confirm that it "plunked" as expected? You indicate that you tested the rounds in a case gauge, but it is not clear that you also tested them in the chamber. Link to comment Share on other sites More sharing options...
usmc1974 Posted March 30, 2023 Author Share Posted March 30, 2023 23 minutes ago, TonytheTiger said: If it was a tight chamber bolt would still close fine on an empty chamber. Kind of a strange thing happened I took the bolt Out of the carrier , And took the extractor Apart And When I took the bolt out of the carrier The firing pin retaining pin was bent And little pc of metal fell out of it and when I took the Extractor apart It had little pc of crud in it. This was Suppose to be a new bcg. Anyway I removed the little rubber donut Then the bolt cycled very smooth on an empty chamber. When I added a round it still did not want to go 100% in the battery. So I'm hoping that the small base dies from RCBS will do the trick. Link to comment Share on other sites More sharing options...
usmc1974 Posted March 31, 2023 Author Share Posted March 31, 2023 I went to sports academy and picked up a box of factory 762x51 ammo. They all cycle smooth as glass, even cycling them slow. I figure the RCBS small base dies should do the trick.. Link to comment Share on other sites More sharing options...
usmc1974 Posted May 10, 2023 Author Share Posted May 10, 2023 (edited) I changed out the Recoil spring With a tubs flat wire recall spring. I think That took care of the problem. it cycles all the rounds pretty smooth, now. I have not actually took it out and Shot it yet, Because I also ordered an Areo Precision enhanced bolt and carrier. That will be here in a couple of days. Edited May 10, 2023 by usmc1974 Link to comment Share on other sites More sharing options...
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