Robocop1051 Posted August 5, 2014 Report Share Posted August 5, 2014 I say it's a .260 Rem 6.5 Creedmoor or Lapua barrel... (The .260 uses .308 brass, so it should be made it deeper) Quote Link to comment Share on other sites More sharing options...
98Z5V Posted August 5, 2014 Report Share Posted August 5, 2014 But, Mega only makes a .308 Win barrel. They don't make any other barrels at this time... Quote Link to comment Share on other sites More sharing options...
Toolndie7 Posted August 5, 2014 Report Share Posted August 5, 2014 Is the case simply hanging up on the ejector and not allowed to sit in-line with the bolt? Like the case is caught between the extractor and ejector pin in the 3rd pic above. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted August 5, 2014 Report Share Posted August 5, 2014 Well the OP said this chamber head spaced correctly & will take him at his word & it feeds by hand & fires , so we can assume the chamber is OK . Now as was noted above , the extractor is not in the Cartridge base grove & that could be because of how it was fed ( slowly by hand ? ) If I see any kind of lip or step on a feed ramp , they get altered & polished , but I see that mostly on AR 15"s with miss matched M4 ramp & non M4 barrel extensions . The brass doesn't seem to have the telltale makes of a bad angle feed , because these 308's will almost bend a round in half & I always see the locking lug makes on the brass , so I believe the round may be going in farther into the chamber before stopping & with the round not positioned into the extractor , it could wedge in the chamber . Notice in one photo the cartridge on the right is bent , but look at the dents in the brass. Here's how I measured the inserted mag. /with ammo , this is in a DPMS lower , I didn't have a mag release in the CMMG & didn't feel like looking for one . Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 5, 2014 Author Report Share Posted August 5, 2014 Ok....I just got a chance to look at all the traffic on this today. Yes - I did headpspace bolt to barrel with the following gauges: http://www.midwayusa.com/product/638620/ptg-headspace-go-gage-243-winchester-260-remington-7mm-08-remington-308-winchester-338-federal-358-winchester?cm_vc=ProductFinding http://www.midwayusa.com/product/643952/ptg-headspace-no-go-gage-243-winchester-260-remington-7mm-08-remington-308-winchester-338-federal-358-winchester?cm_vc=ProductFinding I did fire the gun by inserting a bullet into the barrel. It fired, extracted, and ejected the round. The pictures of the round being fed in my post number 39 where done by pulling the charging handle all the way back and releasing. I did not slowly cycle the bolt forward. I The brass doesn't seem to have the telltale makes of a bad angle feed , because these 308's will almost bend a round in half & I always see the locking lug makes on the brass , so I believe the round may be going in farther into the chamber before stopping & with the round not positioned into the extractor , it could wedge in the chamber . I would agree that the round is not square with the bolt head and extractor when it binds in the chamber. Would this be magazine related. I have 4 metal magazine arriving on Thursday. I still feel I made a big mistake buying a lower and upper from Aero since this was their first batch. Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 5, 2014 Author Report Share Posted August 5, 2014 Have you tried pushing the bottom of the mag towards the muzzle and cycling the action? Your feed ramps on your barrel extension are what my money is on right now. Try pushing and holding the bottom of the mag forward (towards muzzle) and cycle the bolt, releasing the charging handle at the extreme rear of it's travel. If it loads rounds correctly in that manner, see if it will cycle correctly being fired in that manner. There is a possibility of your mag well angle being incorrect, but it's so slight that it's almost impossible. Yes sir....I tried that. I know another poster asked me that earlier. I did not help. Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 5, 2014 Author Report Share Posted August 5, 2014 Here's how I measured the inserted mag. /with ammo , this is in a DPMS lower , I didn't have a mag release in the CMMG & didn't feel like looking for one . DSCN2148.JPG DSCN2147.JPG I measured the rear of the mag with 20 round loaded to the top of the highest rounds rim and got .398. Seems like it as low like your CMMG with Pmag. Quote Link to comment Share on other sites More sharing options...
shibiwan Posted August 6, 2014 Report Share Posted August 6, 2014 I'm now wondering if the barrel isn't lined up with the bore of the upper receiver correctly.... you could try lapping the threaded end of the upper to line it up..... Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 6, 2014 Author Report Share Posted August 6, 2014 The barrel fit fairly snug in the receiver. The barrel extension seemed pretty true when installed into the upper receiver. Quote Link to comment Share on other sites More sharing options...
DNP Posted August 6, 2014 Report Share Posted August 6, 2014 Do you have anyone near you, anyone at all, with another built lower you can slap that upper on? Narrow it down to which half is screwy. Yes, that's a technical term. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted August 6, 2014 Report Share Posted August 6, 2014 I still feel I made a big mistake buying a lower and upper from Aero since this was their first batch. Contact Aero Precision, if the issue is machining - they will make that right, for sure. Quote Link to comment Share on other sites More sharing options...
shibiwan Posted August 6, 2014 Report Share Posted August 6, 2014 (edited) The barrel fit fairly snug in the receiver. The barrel extension seemed pretty true when installed into the upper receiver. not about the snugness... the front "face" of the upper (where the threads are) may not be 100% square (perpendicular) to the bore on the receiver so it all seems to fit in nice and when you torque the barrel nut in, the barrel pulls ever so slightly to one side. Just throwing out ideas of what could be wrong. Seems like it's something to do with the rapid feeding with the BCG slamming the round home causing it to bend, and not chamber right. Probably an issue with tolerance stacking especially with a first-run batch. BTW this is what an AR15 lapping tool looks like. Haven't found one for a 308 AR so I'll probably have to make a couple when we start offering our 308 uppers. Edited August 6, 2014 by shibiwan Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 6, 2014 Author Report Share Posted August 6, 2014 not about the snugness... the front "face" of the upper (where the threads are) may not be 100% square (perpendicular) to the bore on the receiver so it all seems to fit in nice and when you torque the barrel nut in, the barrel pulls ever so slightly to one side. Sorry....my post was confusing. The barrel looked square before torquing down the barrel nut. Looked like the barrel extension was making good contact on all sides of the upper receiver. The hole looked concentric to my eyes. I think the hardest part is eyeballing what is the issue when I may be dealing with minimal tolerances being out. Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 6, 2014 Author Report Share Posted August 6, 2014 (edited) Do you have anyone near you, anyone at all, with another built lower you can slap that upper on? Narrow it down to which half is screwy. Yes, that's a technical term. I went to the local sporting good store and talked to a guy that worked there. I know he had an AR 308 variant. It turned out he has an LMT 308. The sucky part is most AR 308s are not interchangeable. My guess is a DPMS upper should fit, but as many have mentioned in this post we may be dealing with tolerance stacking. If anyone is in the North Eastern Ohio area and would like help with my abortion of a gun, please contact me. Edited August 6, 2014 by warthog984 Quote Link to comment Share on other sites More sharing options...
Toolndie7 Posted August 6, 2014 Report Share Posted August 6, 2014 For shi*s and giggles take your ejector pin out and put a single round in the mag and send the bolt home. See if it chambers a round.... Quote Link to comment Share on other sites More sharing options...
survivalshop Posted August 6, 2014 Report Share Posted August 6, 2014 (edited) I mentioned that before, check to make sure the Ejector or Extractor is forcing the cartridge to one side & not letting it feed into the chamber . I would disassemble the Bolt & clean & inspect for any thing that might cause them to bind . Just manipulating them should tell you something . Try the new mags you are getting & go from there . I believe the cartridge base doesn't seat onto the extractor until the cartridge seats in the chamber , the Ejector is putting pressure on the base while feeding & if the Extractor is not in the cartridges bases extractor grove , it should be putting a nullifying pressure or force against the pressure or force from the Ejector, so the round should feed straight into the chamber ,with out it getting cocked to one side or the other from those opposing forces , if you follow my thinking . I moved from NE Ohio ten years ago , I lived in the Cleveland area. Edited August 6, 2014 by survivalshop Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 6, 2014 Author Report Share Posted August 6, 2014 Silly question. Should there be a lot more tension the the 308 ejector than say and AR15 ejector. I have to push pretty hard. Quote Link to comment Share on other sites More sharing options...
Toolndie7 Posted August 6, 2014 Report Share Posted August 6, 2014 I believe the cartridge base doesn't seat onto the extractor until the cartridge seats in the chamber , the Ejector is putting pressure on the base while feeding & if the Extractor is not in the cartridges bases extractor grove , it should be putting a nullifying pressure or force against the pressure or force from the Ejector, so the round should feed straight into the chamber ,with out it getting cocked to one side or the other from those opposing forces , if you follow my thinking . Thats pretty much what I've been saying. Essentially a 3 point jam, which is why I suggested taking out the ejector to prove out the problem. Everybody seems very quick to start blaming mags and checking everything to the .001 lol. This platform is pretty forgiving, keep it simple and check the basics first. Quote Link to comment Share on other sites More sharing options...
Toolndie7 Posted August 6, 2014 Report Share Posted August 6, 2014 Silly question. Should there be a lot more tension the the 308 ejector than say and AR15 ejector. I have to push pretty hard. Yes. There is a lot more pressure. Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 6, 2014 Author Report Share Posted August 6, 2014 I moved from NE Ohio ten years ago , I lived in the Cleveland area. I live 20 miles south of Cleveland. Medina County Quote Link to comment Share on other sites More sharing options...
warthog984 Posted August 6, 2014 Author Report Share Posted August 6, 2014 Yes. There is a lot more pressure. Ok...I am going to take some pictures of the bolt before and after disassemble. Also, I am using Springco extractor springs. I am going to put the factory spring back in it. Quote Link to comment Share on other sites More sharing options...
Toolndie7 Posted August 6, 2014 Report Share Posted August 6, 2014 Ok...I am going to take some pictures of the bolt before and after disassemble. Also, I am using Springco extractor springs. I am going to put the factory spring back in it. Be sure to leave the extracor assembled and remove just the ejector to try and isolate the problem. One thing at a time. Quote Link to comment Share on other sites More sharing options...
Magwa Posted August 6, 2014 Report Share Posted August 6, 2014 I think its a mag problemo.....check your mag release....is the stud almost even with the mag button? does the mag drop freely? put a round in a mag with bolt back in the catch.....look inside thru the ejection port and see how the round looks/angle in relationship to the ramps.....mag has to be high enough so the round looks like it will slide right into chamber....seen this before......you may have to tweak the mag lips to get proper angle/height also your mag spring/follower...could be hanging up....take a lil oil and a dowel push down a few times on the mag........the mag aint positioned right in the magwell is is my 2 cents :) Wash This is my thought as well , if you get a metal mag and it does the same thing try lifting the lips of the mag just a tiny bit at a time to see if it changes the angle required to feed the round.. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted August 7, 2014 Report Share Posted August 7, 2014 (edited) I live 20 miles south of Cleveland. Medina County Drive out to ADCO and let Steve look at your rifle. There isn't anyone better qualified to diagnose your issue, in person, than him. You're lucky you live that close - he's one of the best AR Armorers in the entire country. He's in Sylvania. EDIT - Call first, and set it up. Don't just drive out there... Edited August 7, 2014 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted August 7, 2014 Report Share Posted August 7, 2014 Drive out to ADCO and let Steve look at your rifle. There isn't anyone better qualified to diagnose your issue, in person, than him. You're lucky you live that close - he's one of the best AR Armorers in the entire country. He's in Sylvania. EDIT - Call first, and set it up. Don't just drive out there... And tell him who sent you! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.