308lrnewb Posted November 22, 2016 Report Share Posted November 22, 2016 So, I have seasoned.. fired and dialed in the mega. I keep having two sporadic issues. Randomly, three known good DPMS magazines will fail to chamber. The other rifle functions fine with them. I pull the bolt back and notice the follower is tipped. Projectiles facing chamber, headstamp angled towards the pistol grip. So, I inspected for gas leaks. I see very minor soot deposits around the gas tube. I do not think this is the issue. It is running full gas. The tube port was opened to match the gas block port. Everything lines off. The issue is intermittent. Rifle will fire fine for a while, then this issue appears. Also, the bolt lock open seldom functions. Worked more in the first single shots than anywhere else. So, I have inspected the rifle for some time. This evening, I broke down both rifles. I swapped BCG's and retained the same magazine while hand testing the system. Something stands out.. What is this?? .. The dial caliper comes out. Strange... Measuring from the top of DPMS brand bolt catch(both DPMS and Mega rifles) revealed interesting numbers. Mega: Catch down - 0.22" Catch up - 0.44" DPMS: Down - 0.21(0.208" measured) Up - 0.52" These measurements were with the farthest travelling portion (right hand side) piece of the bolt catch to the lower receiver face that mates with upper receiver. I manipulated the hold open/catch mechanism by hand to ensure full strokes in both directions. The measurements were obviously done while installed in a functioning lower. Just so to preclude any clutter in this thread. I have yet to contact Mega about any tolerance specifications. One thing I have noticed - The DPMS visibly has the bolt catch 1/10"(approximated, this was by vision through ejection port) higher against the bolt face. In the Mega, the bolt catch does not elevate beyond the lugs. The DPMS rifle obscures almost the entire lower portion of bolt. I checked both carriers in each rifle. Results were consistent. I am unsure if the ambidextrous MATEN lower has less travel with the bolt catch system design. Anyone have experience here? ------------------- In recap: Rifle is still doing final break in. It has had 140 rounds fired through it, no more. I personally think the gas system is not an issue. I barely got any soot/carbon fouling to cover my bore patch when vigorously rubbing the tube and block. I am anticipating the failure to feed (bolt goes right over brass, does not strike headstamp to strip. rounds are canted 45*, tips facing up) is due to the rifle still being awful tight. The FTF issue has mostly done away with itself. Next trip to Midway will bring a 500round batch of federal city. Rifle was fired 100 times in less than a two hour span while doing barrel break in. It ran very steady on the twenty-round magazine. Ten rounders are a bit more of concern to me currently, being the hunting season. I first was concerned with a short stroke issue - Rifle is running slash's xh rifle buffer and a standard spring. Recoil is very tame. However, the brass is falling 4-8ft away and is very consistent at 4-5 o'clock throws. Issues are persistent when using m80 surplus and 168 smk handloads. The handloads were 38.5gr of h4895. ----------------- Ideas? Rifle passes headspace, everything is smoothly riding. Running lithium grease on internals with slip2000 EWL for wet work. Never fails to lock, no weak primer strikes. I have noticed every few more rounds put down, it is smoothing more and seems to cycle softer. Not in any mood to throw parts right now. Also - the magazine itself sets at very similar heights when seated against the mag catch for both lowers when using same magazine. I personally am thinking it needs a few more rounds, but hey... Oh, I was stringing consistent and tight patterns with m80. Was getting less than 1.5" patterns with it before round #100. Quote Link to comment Share on other sites More sharing options...
308lrnewb Posted November 23, 2016 Author Report Share Posted November 23, 2016 Thank you to everyone whom participated in this discussion! It is now closed. For any one struggling with rifle issues akin to mine.. After thinking all night long about this, I broke down the fore end of rifle. The gas tube needed a punch to be removed from block(after roll pin was uninstalled). Dial caliper went on everything. Turns out Criterion misaligned the gas port and the gas block set screw dimple by about 10*. Rifle functions on lock back every time. No more failures to feed. Ejection is a steady 4.5-5.5ft at 5o'clock. Look guys - A whole functioning AR308 rifle, not a single helping hand. Which members said it couldn't be done? ---------------------------- I also want to gratefully thank D.Wilson because his bolt carrier group is amazing. Side by side comparison to a standard DPMS BCG shows quite a bit more workmanship. The spacing for hammer is better, there is a slightly more generous scallop on the carrier for the ejection door to ride in and it is nicely fluted. The nitride finish is impeccable with no blemishes. His bolt was spot on for headspace and has not mangled any brass. After sorting 140 finely tumbled brass, I see no ejector smears or extractor nibbles. Consistent, well made and excellently priced. This guy knows his stuff. For anyone struggling to disassemble the bolt itself.. I used a winchester 45acp brass along with a bench vice and some wood scraps. The brass went into the bolt, bolt was then sandwiched between the two woods. I let the rear side of bolt dig in to one wood scrap(side that firing pin installs to) while the 45acp brass compressed the ejector. Then, a small ballpeen hammer and roll pin punch.. a couple well placed smacks and apart it went. Assembled in reverse, very easy. The bolt I received had dual coils for extractor, no doughnuts. Ejector had a single coil. Lubricated everything with a fine synthetic and it is turning like a top. He has my business for future builds. Another large acknowledgement goes to Clint of Heavy Buffers. He answered multiple emails pertaining to various 'non-standard' parts combinations. He also has my business for future builds. His product is a notch above the rest. The rifle feels pretty tame. Interested to see how things change when I throw a titan comp on the end of this barrel. Currently, it is bare threads. ------------------------------ Thank you again. Quote Link to comment Share on other sites More sharing options...
blue109 Posted November 23, 2016 Report Share Posted November 23, 2016 54 minutes ago, 308lrnewb said: It is now closed. You're not the boss of me Quote Link to comment Share on other sites More sharing options...
mrmackc Posted November 23, 2016 Report Share Posted November 23, 2016 1 hour ago, 308lrnewb said: Thank you to everyone whom participated in this discussion! It is now closed. For any one struggling with rifle issues akin to mine.. After thinking all night long about this, I broke down the fore end of rifle. The gas tube needed a punch to be removed from block(after roll pin was uninstalled). Dial caliper went on everything. Turns out Criterion misaligned the gas port and the gas block set screw dimple by about 10*. Rifle functions on lock back every time. No more failures to feed. Ejection is a steady 4.5-5.5ft at 5o'clock. Look guys - A whole functioning AR308 rifle, not a single helping hand. Which members said it couldn't be done? ---------------------------- I also want to gratefully thank D.Wilson because his bolt carrier group is amazing. Side by side comparison to a standard DPMS BCG shows quite a bit more workmanship. The spacing for hammer is better, there is a slightly more generous scallop on the carrier for the ejection door to ride in and it is nicely fluted. The nitride finish is impeccable with no blemishes. His bolt was spot on for headspace and has not mangled any brass. After sorting 140 finely tumbled brass, I see no ejector smears or extractor nibbles. Consistent, well made and excellently priced. This guy knows his stuff. For anyone struggling to disassemble the bolt itself.. I used a winchester 45acp brass along with a bench vice and some wood scraps. The brass went into the bolt, bolt was then sandwiched between the two woods. I let the rear side of bolt dig in to one wood scrap(side that firing pin installs to) while the 45acp brass compressed the ejector. Then, a small ballpeen hammer and roll pin punch.. a couple well placed smacks and apart it went. Assembled in reverse, very easy. The bolt I received had dual coils for extractor, no doughnuts. Ejector had a single coil. Lubricated everything with a fine synthetic and it is turning like a top. He has my business for future builds. Another large acknowledgement goes to Clint of Heavy Buffers. He answered multiple emails pertaining to various 'non-standard' parts combinations. He also has my business for future builds. His product is a notch above the rest. The rifle feels pretty tame. Interested to see how things change when I throw a titan comp on the end of this barrel. Currently, it is bare threads. ------------------------------ Thank you again. Okay so what is closed? Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted November 23, 2016 Report Share Posted November 23, 2016 Not quite sure why you'd be so upset no one commented. It's the holidays and most people here have full time jobs. Also I don't think anyone said it can't be done with out help, but it's always been noted these aren't as easy as small frame Guns. Good job figuring out the issue. Quote Link to comment Share on other sites More sharing options...
shepp Posted November 23, 2016 Report Share Posted November 23, 2016 8 minutes ago, edgecrusher said: Not quite sure why you'd be so upset no one commented. It's the holidays and most people here have full time jobs. Also I don't think anyone said it can't be done with out help, but it's always been noted these aren't as easy as small frame Guns. Good job figuring out the issue. Or maybe it's your past history here, goodbye ??✌?️ Quote Link to comment Share on other sites More sharing options...
mrmackc Posted November 23, 2016 Report Share Posted November 23, 2016 We are glad you got this problem figured out on your own. I've done this before, way back there when there was no internet and a couple of times since I started surfing. It feels good to discover the old bucket still holds a brain, don't it! Welcome! and thanks for adding to the quality of the site. Quote Link to comment Share on other sites More sharing options...
unforgiven Posted November 23, 2016 Report Share Posted November 23, 2016 7 hours ago, blue109 said: You're not the boss of me and that's why we can't have anything nice.... Quote Link to comment Share on other sites More sharing options...
survivalshop Posted November 24, 2016 Report Share Posted November 24, 2016 Of course it couldn't be the Gas Block was off a bit ! Mistakes can be made with any product , but I Measure Gas Ports to align ALL my Gas Blocks . Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted November 24, 2016 Report Share Posted November 24, 2016 Just now, survivalshop said: Of course it couldn't be the Gas Block was off a bit ! Mistakes can be made with any product , but I Measure Gas Ports to align ALL my Gas Blocks . Paper towel tubes work GREAT for that alignment. It then allows you to move the gas properly and swiftly, to the nose of an unsuspecting friend or sibling. Wait, what were we talking about? Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted November 24, 2016 Report Share Posted November 24, 2016 54 minutes ago, planeflyer21 said: Paper towel tubes work GREAT for that alignment. It then allows you to move the gas properly and swiftly, to the nose of an unsuspecting friend or sibling. Wait, what were we talking about? 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.