Domino Posted May 5, 2015 Report Share Posted May 5, 2015 AERO M5 First iteration was an 18" BHW barrel mid gas. Chamber tighter than it should have been, but worked through it. Fired around 250 rounds suppressed with no issues using an adjustable gas block with about 20% restriction. Shooting 168/175 match exclusively. Opened up gas system to 100% and removed suppressor. Got about 40 rounds of 7.62x51 Winchester white box through it and the extractor broke. Replaced the extractor with a new Leitner-Wise extractor and used old extractor spring. After about ten rounds, the rifle began double feeding (one spent, one live) and stove piping. Replaced extractor spring with springco 5-coil with inner spring, and orange buffer spring. Failure to extract 100% of the time. Everyone I inquired with said it sounded like a tight chamber. Installed new Faxon 18" mid length gas barrel, regular gas block, and new gas tube. 100% failure to extract. I noticed that the sprinco extractor spring has about 1/2 of the spring force of a well worn DPMS factory bolt extractor spring. I installed the DPMS BCG (1500+ rounds on it) and now get extraction/ejection 80% of the time, with the other 20% failure to eject, with the empty case is sitting on the empty magazine with the bolt locked back. The rounds that do extract and eject are barely getting out of the ejection port, landing right next to the rifle. It is more like they are falling out instead of being launched out. (This DPMS BCG will sling the brass 6' out when in its parent LR-308 rifle.) The rim of the ejected cases have decent claw marks on them from the DPMS extractor. At this point, I believe the new Faxon barrel needs to break in as an unspent round in the chamber is difficult to remove (similar to the what the new BHW barrel was doing when new.) Thoughts? Ideas? Will overgassing cause extraction issues? I ask because all of this started after I opened up the gas system (and subsequently stopped using the suppressor.) Quote Link to comment Share on other sites More sharing options...
Toolndie7 Posted May 5, 2015 Report Share Posted May 5, 2015 sounds like you went through the extractor pretty well, but what kind of shape is the ejector and spring in? Quote Link to comment Share on other sites More sharing options...
Domino Posted May 5, 2015 Author Report Share Posted May 5, 2015 sounds like you went through the extractor pretty well, but what kind of shape is the ejector and spring in? The ejector and spring are fine. The DPMS BCG flings the brass in the parent rifle, but not in this rifle. The ejector tension in the orginal bolt is higher than the DPMS ejector. I am really starting to believe it is a combination of weak extractor spring (now installing two o-rings and on black buffer with the Sprinco extractor springs - feels like it should), and over gassed. So I am going to put the adjustable gas block back on it, dial it down, and see what that does. Quote Link to comment Share on other sites More sharing options...
Tripledeuce Posted May 5, 2015 Report Share Posted May 5, 2015 Have the tight chamber opened up! The case is still stuck to the chamber walls, and that can easly cause the case to not eject. Respectfull Terry Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 5, 2015 Report Share Posted May 5, 2015 Polish the chamber also . You should not , as you probably know ,swap Bolts in different barrels . I can see where a Bolt that is broken in , in one Barrel, may not perform in a Barrel Extension of another one , even if Head Space passed in both . Meaning , it my extract fine in one ,but may not in the other Barrel . You can over do the spring pressure on that Extractor & cause problems also . Over gassing may also be an issue . Are you using the same magazines , have you tried different brands ? Quote Link to comment Share on other sites More sharing options...
Domino Posted May 5, 2015 Author Report Share Posted May 5, 2015 Polish the chamber also . You can over do the spring pressure on that Extractor & cause problems also . Over gassing may also be an issue . Are you using the same magazines , have you tried different brands ? It took very little pressure to bottom out the extractor. It felt like there was little more than nerf foam for spring tension. The gas hole in the new barrel measures 3/32" plus or minus, and I have no idea if that is large or small, but it is the same as the BHW gas hole. I have tried with four different magazine brands/types for the DPMS pattern 308. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 6, 2015 Report Share Posted May 6, 2015 (edited) 0.094" for the gas port. Seems large, as that's what you run for a 300BLK barrel (or close to it). I can't remember what my Fulton .308 barrel was, and those notes are long gone now. Someone here will have a reference. I'll go measure my unbuilt Rainier 18" barrel and report back in here. Rainier Arms Select 18" SS barrel, midlength gas system, 0.080" gas port in the barrel. Edited May 6, 2015 by 98Z5V Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 6, 2015 Report Share Posted May 6, 2015 I looked at the notes on my 16" Criterion , rifle length gas system & its 0.1095", A mid or Carbine system may be different . We need a Pinned subject on Manufacturers Barrels gas port sizes . Quote Link to comment Share on other sites More sharing options...
Domino Posted May 12, 2015 Author Report Share Posted May 12, 2015 The problem was two-fold: The spinco double extractor spring was far too soft. I installed one extractor buffer under the inner spring and installed two o-rings over the outer extractor spring to get the proper tension on the extractor. I re-installed the adjustable gas block and from the closed position found the sweet spot at 1.25 turns out. It worked instantly, and ejected the brass about 6-8' consistently. FWIW, I just received another Faxon barrel and the gas hole on it was about .047 diameter. Why the other one was so much larger, I do not know. Maybe they figured it out and changed it. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 13, 2015 Report Share Posted May 13, 2015 0.047" seems TINY. I've never seen a gas port that small in a .308 AR barrel, or a 5.56 barrel. What gas system is that new barrel using? Quote Link to comment Share on other sites More sharing options...
Domino Posted May 13, 2015 Author Report Share Posted May 13, 2015 (edited) 0.047" seems TINY. I've never seen a gas port that small in a .308 AR barrel, or a 5.56 barrel. What gas system is that new barrel using? I have not yet installed it, but I was probably going to run another adjustable DI system. I do not have all of the parts to put it together yet. The 1.25 turns on the build above was probably near the equivalent of .05ish, since that is very little off the bottom. Edited May 13, 2015 by Domino Quote Link to comment Share on other sites More sharing options...
EngrBob Posted May 13, 2015 Report Share Posted May 13, 2015 Faxon web site lists the gas port diameters for both the 18" stainless and moly barrels at 0.081. Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted May 13, 2015 Report Share Posted May 13, 2015 I have not yet installed it, but I was probably going to run another adjustable DI system. I do not have all of the parts to put it together yet. The 1.25 turns on the build above was probably near the equivalent of .05ish, since that is very little off the bottom. He meant what length gas system does your barrel use, carbine, mid or rifle. BTW, my 20" .308 BHW barrel's gas port looks to be .099, but it's a rifle length gas system. Quote Link to comment Share on other sites More sharing options...
Toolndie7 Posted May 13, 2015 Report Share Posted May 13, 2015 I have not yet installed it, but I was probably going to run another adjustable DI system. I do not have all of the parts to put it together yet. The 1.25 turns on the build above was probably near the equivalent of .05ish, since that is very little off the bottom. Thats funny cause most blocks have a 10-32 thread. 1-1/2 turns on that thread is .046 will be interesting to see if that faxon barrel with the 047 hole runs as it is Quote Link to comment Share on other sites More sharing options...
Domino Posted May 13, 2015 Author Report Share Posted May 13, 2015 He meant what length gas system does your barrel use, carbine, mid or rifle. BTW, my 20" .308 BHW barrel's gas port looks to be .099, but it's a rifle length gas system. I see. It is a mid-length gas system. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 14, 2015 Report Share Posted May 14, 2015 I don't think 0.047" gas port is gonna get it on a midlength gas 18" .308 barrel. My opinion. Too small. Quote Link to comment Share on other sites More sharing options...
washguy Posted May 14, 2015 Report Share Posted May 14, 2015 I don't think 0.047" gas port is gonna get it on a midlength gas 18" .308 barrel. My opinion. Too small. Yep ...thats way small...#44 #45 drill bit will cure it bout .0860 will help it :) Wash Quote Link to comment Share on other sites More sharing options...
Ronbo Posted May 14, 2015 Report Share Posted May 14, 2015 I went to .093 on my custom built 24" ar 308 barrel after .080 was way too small with my reloads of 43 grains of 335 with 150 grain bullets or 40 grains with 168 grains. Cycles perfectly now with either load. I'm using a rifle length gas system. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 14, 2015 Report Share Posted May 14, 2015 New Barrel , never installed , contact the Manufacturer about it & send it back if need be . Quote Link to comment Share on other sites More sharing options...
FaxonNathan Posted May 25, 2015 Report Share Posted May 25, 2015 The problem was two-fold: The spinco double extractor spring was far too soft. I installed one extractor buffer under the inner spring and installed two o-rings over the outer extractor spring to get the proper tension on the extractor. I re-installed the adjustable gas block and from the closed position found the sweet spot at 1.25 turns out. It worked instantly, and ejected the brass about 6-8' consistently. FWIW, I just received another Faxon barrel and the gas hole on it was about .047 diameter. Why the other one was so much larger, I do not know. Maybe they figured it out and changed it. Whoah! First, our apologies for not keeping up with this forum. We need to work on that... Second, that sounds highly unusual gas port diameter. I know we use a .094 bit in that drilling operation, so something must be off. If you have not contact us, please do so and we will get you squared away! Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 25, 2015 Report Share Posted May 25, 2015 i knew that was a small gas port... <lmao> That's good stuff, Nathan. <thumbsup> Quote Link to comment Share on other sites More sharing options...
mrmackc Posted May 25, 2015 Report Share Posted May 25, 2015 The problem was two-fold: The spinco double extractor spring was far too soft. I installed one extractor buffer under the inner spring and installed two o-rings over the outer extractor spring to get the proper tension on the extractor. I re-installed the adjustable gas block and from the closed position found the sweet spot at 1.25 turns out. It worked instantly, and ejected the brass about 6-8' consistently. FWIW, I just received another Faxon barrel and the gas hole on it was about .047 diameter. Why the other one was so much larger, I do not know. Maybe they figured it out and changed it. You weren't by chance using a #47 drill bit to measure the gas port were you? A #47 drill bit measures 0.785 inches. My DPMS LR308 16 " barrel measures .076 inches = to a #48 drill bit. Quote Link to comment Share on other sites More sharing options...
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