EdgeReady Posted April 22, 2020 Report Share Posted April 22, 2020 ALL build parts matched and provided by Ballistic Advantage BA5 (Aero M5) Upper receiver 6.5CM BA Nickel-Boron BCG 14.1" Hanson bbl Carbine length gas system Superlative 0.625 Melonite Gas Block BA5 (Aero M5) Lower receiver Geissle 2-stage trigger UBR stock (currently using spacer to acheive 7" carbine tube) Currently Heavybuffer SS CAR-10 buffer (I have an assortment) Springco Orange 308 spring (I have an assortment) Surefire Warcomp flash hider Currently Unsuppressed Using 140gr Sellier & Bellot SMK for testing (have tried others) Hello Gents, hope all is well with all of you. I started this build a year ago, but I put it down when I got busy with a new business and I'm just circling back to it. Despite meticulous attention during the build and adherence to all specs and instructions, the rifle always behaves under-gassed. The rifle fails to lock back on an empty magazine and the ejection force is minimal. The rifle has at times locked back on the BC during different phases of testing, but rarely. The rifle even behaved under-gassed when suppressed. Below is a brief snapshot of what I've done in the way of troubleshooting, to the best of my recollection... * Verified proper barrel torque * Verified proper alignment of the gas tube & gas key. Gas tube alignment is straight outside and inside the upper receiver. The gas tube falls about 1/8" passed the center of the cam cutout. There is no evidence of wear marks from misalignment of the gas tube and gas key. * Verified that gas tube is clear - passes air, passes light, & passed a long pipe cleaner * Verified proper alignment of the gas block with the gas port. Spent alot of time on this and reconfirmed using different methods. Currently, gas stain is right on the hole. * Verified proper setup and function of the gas block in adjustment and passing air, light, and wire * Check gas key position, tightness, and clear of obstructions * Inspected all other parts of BCG * Did research and played extensive buffer games according to research. I have an assortment of various springs and buffers to test with. * Did extensive single shot - empty mag testing with various gas & buffer settings * Inspected and checked function of bolt catch * Checked headspace, all checks tested within spec * Acquired a spare BCG from BA and tested again with that too * Scoped chamber & bore to inspect for deformities * Finally sent the upper back to BA. They tested it on a lower with a rifle buffer system and reported that it functioned normally. My main suspicions are... 1. The gas port is drilled too small for this short barrel. I presently lack the ability to measure the diameter of this hole, although I researched what is needed. I did discuss this with the mfgr - they do not agree and report normal rifle function when I sent it back. 2. I'm missing some voodoo combination of buffer parts to make the carbine buffer system work 3. Some problem at the gas tube / BCG connection possibly involving the gas tube being a tad long or some other factor contributing factor. That's my story...looking forward to the sweet success of solving the problem and shooting accurately. Quote Link to comment Share on other sites More sharing options...
Dragonscout Posted April 23, 2020 Report Share Posted April 23, 2020 Welcome to the boards from middle Georgia! Looks like there's a lot I may learn from ya. Always been a shooter, not a mechanic. I'm absorbing more as I gain full geezership tho. You came to the right place for help though. Settle in for the ride... Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted April 23, 2020 Report Share Posted April 23, 2020 Have you tried a lighter buffer? Quote Link to comment Share on other sites More sharing options...
Rsquared Posted April 23, 2020 Report Share Posted April 23, 2020 Welcome aboard from Maryland. Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 23, 2020 Author Report Share Posted April 23, 2020 (edited) By the way, I'm a newbie and I said my introductions a few days ago. I'm just getting around to presenting my current technical situation. I have all the typical sizes of buffer and an assortment of springs. Some time ago, I did experiment with various arrangements. I did not achieve function during that phase of testing, although I did affect the system to a point where I saw different effects ranging from failures to feed, stove pipes, and failure to extract. There were so many variables to contend with between the gas block settings, buffer spring, and buffer. Today, I tested using the Orange heavy spring from SpringCo. I was not able to get the bolt to lock back even with the gas block fully open. It still behaves like there is insufficient gas pressure. When the round ejected today, it just tumbled across my right arm on it's way down. Not much throw at all. Because my previous "buffer games" were some time ago, I'm going to play them again this weekend to reconnect with the results. Edge Edited April 23, 2020 by EdgeReady Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted April 23, 2020 Report Share Posted April 23, 2020 Until you get it to function there is no need to try any gas block setting but wide open. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 23, 2020 Report Share Posted April 23, 2020 2 hours ago, EdgeReady said: 14.1" Hanson bbl Superlative 0.625 Melonite Gas Block UBR stock (currently using spacer to acheive 7" carbine tube) You actually have the UBR 2 with the 7 5/8" internal depth receiver extension, so slap either an Armalite AR-10 Carbine buffer or an AR15 Carbine H3 buffer in there, with an Armalite EA1095 recoil spring. That's what MagPul recommends for this stock anyway, for .308ARs. That's not gonna solve your problem, though - your gas port is too small, and it's gonna need measured, report back, then drilled up. Always test an adjustable gas block Wide Open, until you get a functioning gun. After that, you tailor it to your preference/load. Numbered drill bits work best for measuring gas port diameters - they're cheap, and you can pick up the Irwin brand at any Ace Hardware store. Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 23, 2020 Author Report Share Posted April 23, 2020 I'll play with some more buffers this weekend, but I'm with you on the gas port. I'm thinking someone didn't swap the bit before it was time to ream the gas ports in the lot of short barrels. I'll get the gas port measuring done. I take it your suggesting a set of numbered machinists bits for measuring the port diameter. If I do confirm the gas port is too small, do you think I can get the reaming/drilling done myself? I do have a Bridgeport Mill and I'm not afraid to do it. Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted April 23, 2020 Report Share Posted April 23, 2020 19 minutes ago, EdgeReady said: I'll play with some more buffers this weekend, but I'm with you on the gas port. I'm thinking someone didn't swap the bit before it was time to ream the gas ports in the lot of short barrels. I'll get the gas port measuring done. I take it your suggesting a set of numbered machinists bits for measuring the port diameter. If I do confirm the gas port is too small, do you think I can get the reaming/drilling done myself? I do have a Bridgeport Mill and I'm not afraid to do it. There's no need to ream it, drilling will suffice. People drill them by hand with a wooden dowel in the bore, a mill will make it 10x easier. Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 23, 2020 Author Report Share Posted April 23, 2020 Good to hear that I don't need a rocket lab to accomplish a bore increase if it's needed. Is that wooden dowel so that you can just drill until you see wood shavings come out? Also, is it not possible that the exit hole will have a burr in the bore? Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted April 23, 2020 Report Share Posted April 23, 2020 5 minutes ago, EdgeReady said: Good to hear that I don't need a rocket lab to accomplish a bore increase if it's needed. Is that wooden dowel so that you can just drill until you see wood shavings come out? Also, is it not possible that the exit hole will have a burr in the bore? When hand drilling the wood shaving indicate that you've gone far enough, basically preventing drilling a divot in the bottom of the bore. It is certain that a burr will be left at the bottom of the hole, but the first shot afterwards will expedite it's removal. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 23, 2020 Report Share Posted April 23, 2020 59 minutes ago, EdgeReady said: Good to hear that I don't need a rocket lab to accomplish a bore increase if it's needed. Is that wooden dowel so that you can just drill until you see wood shavings come out? Also, is it not possible that the exit hole will have a burr in the bore? 1/4" wooden dowel down the barrel - it's only to prevent you hitting the other side of the barrel bore when you break through. Drill slow, LIGHT pressure, and you shouldn't even need it. Some people have a different perception of "light pressure" on the drill, though. Let the bit do the work - not pressure on the bit, and drill speed. Just let it eat. Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 23, 2020 Author Report Share Posted April 23, 2020 +1 on the drilling and judicious use of pressure. My only fear in this operation is breaking the bit off in the port. Small bits are notorious. We like to use the mill for such operations because we have more control over RPMs and bit feed (manually of course). Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted April 23, 2020 Report Share Posted April 23, 2020 I have drilled several with a cordless drill and cheap chinese bits without issue. Take it up in small increments, lots of lube, and don’t force it. I would be hesitant to use a press or a mill, I like the feedback I get from hand drills and when you go easy they line themselves up, always worried I wouldn’t get the setup just right in a press. Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 24, 2020 Author Report Share Posted April 24, 2020 This weekend I will conduct recoil system games and record the data from all the testing. I have arranged my springs from heaviest to lightest. I'll be using two 308 buffers in the series as well, 5.7oz and 3.7oz. I will track the results of each combination on a spreadsheet. All tests will be conducted at single shot, empty mag, and maximum gas port setting. After these recoil system games are complete, I will use bits to gauge the gas port diameter. Question: if we verify that the gas port is to be drilled out, what increments of enlargement should I shoot for? Is there a typical increase used, or should I just go up bit size by bit size? My main concern is that by moving up gradually over several small increments, I will increase wear & tear over the number of re-assemblies and will increase the chances of bit breakage over many subsequent drilling operations. I would prefer to be more targeted about the diameter increase if this is possible. Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted April 24, 2020 Report Share Posted April 24, 2020 3 hours ago, EdgeReady said: This weekend I will conduct recoil system games and record the data from all the testing. I have arranged my springs from heaviest to lightest. I'll be using two 308 buffers in the series as well, 5.7oz and 3.7oz. I will track the results of each combination on a spreadsheet. All tests will be conducted at single shot, empty mag, and maximum gas port setting. After these recoil system games are complete, I will use bits to gauge the gas port diameter. Question: if we verify that the gas port is to be drilled out, what increments of enlargement should I shoot for? Is there a typical increase used, or should I just go up bit size by bit size? My main concern is that by moving up gradually over several small increments, I will increase wear & tear over the number of re-assemblies and will increase the chances of bit breakage over many subsequent drilling operations. I would prefer to be more targeted about the diameter increase if this is possible. You have an adjustable gas block, drill the gas port up just once to the appropriate diameter and use the adjustable gas block to regulate it to whatever extent you wish. You're defeating the usefulness of the gas block by trying to upsize the gas port incrementally. Technically you could go as high as .125" in a gas port and still regulate it as needed, but you don't need to be that drastic. I'd drill it up to a 3/32" (.094") and use the gas block as it was intended. Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 24, 2020 Author Report Share Posted April 24, 2020 I performed my recoil system tests this evening. Here are the results. As expected, I'm still thinking low gas due to small gas port. Sorry that results do not format well here. All tests done at max gas pressure using 140gr Sellier&Bellot SMK Locked on bolt L Short- lock on carrier SL No lockback NL Failure to eject FTE Stovepipe SP Carbine Length Springs (in order of comp strength) CAR-10 Buffer 5.7oz Eject O'clock Comments 308 Carbine Buffer 3.7oz Eject O'clock Comments SpringCo Orange, 28 coils NL 3-4ish Casing dribbled out onto arm FTE n/a Failure to eject, strong eject to 6ft SpringCo Orange, 28 coils SP n/a 2nd shot, Stovepiped NL 5:00 2nd shot, casing dribbled out to 2ft Spring 2, 24 coils NL 3:30 Ok ejection, not strong, 6ft NL 3:30 Ok ejection, not strong, 5ft Spring 3, 27 coils NL 4:00 Low order ejection, 3ft NL 3:30 Ok ejection, not strong, 5ft Tactical Spring 4, 35 coils NL 3:00 Ok ejection, not strong, 5ft NL 3:30 Ok ejection, not strong, 5ft Yellow, 38 coils NL 4:00 Failure into battery, spring too weak, ok ejection, not strong, 5ft NL 4:00 Failure into battery, spring too weak, ok ejection, not strong, 5ft Notes: All brass is scarred pretty well going across the feed ramp. Common report for 6.5CM AR. I will address later. Any chance these scars cause the casing to grab in the chamber thus requring more force to extract? Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 24, 2020 Author Report Share Posted April 24, 2020 7 hours ago, Matt.Cross said: You have an adjustable gas block, drill the gas port up just once to the appropriate diameter and use the adjustable gas block to regulate it to whatever extent you wish. You're defeating the usefulness of the gas block by trying to upsize the gas port incrementally. Technically you could go as high as .125" in a gas port and still regulate it as needed, but you don't need to be that drastic. I'd drill it up to a 3/32" (.094") and use the gas block as it was intended. Thank you for that guidance. I will shoot for 0.094 and be done with it. Once the gas is flowing as it should, I will redo the recoil system testing at various gas settings. Hopefully I will find the happy & reliable zone. (I will not bother retesting the Yellow spring as I think its way too light). After that, redo the same suppressed. Thanks again. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 25, 2020 Report Share Posted April 25, 2020 6 hours ago, EdgeReady said: Thank you for that guidance. I will shoot for 0.094 and be done with it. Once the gas is flowing as it should, I will redo the recoil system testing at various gas settings. Hopefully I will find the happy & reliable zone. (I will not bother retesting the Yellow spring as I think its way too light). After that, redo the same suppressed. Thanks again. No real need for that. Drill the port, put the appropriate recoil system in there for the stock (UBR 2), and then work your gas to where you want it, via the adjustable block. The appropriate recoil system would be: Armalite AR-10 Carbine buffer, or any AR15 Carbine H3 buffer, and the Armalite EA1095 recoil spring. That's what the UBR 2 was designed to run, and it works very, very well. Quote Link to comment Share on other sites More sharing options...
Magwa Posted April 25, 2020 Report Share Posted April 25, 2020 How well are you lubing your BCG? you are going to want it almost dripping wet with a good oil until the parts have married you can even leave your BCG soaking in something like Mobile one synthetic it is awesome stuff as the oil binds to the metal after a couple of weeks the BCG will always feel lubed Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 26, 2020 Author Report Share Posted April 26, 2020 20 hours ago, 98Z5V said: No real need for that. Drill the port, put the appropriate recoil system in there for the stock (UBR 2), and then work your gas to where you want it, via the adjustable block. The appropriate recoil system would be: Armalite AR-10 Carbine buffer, or any AR15 Carbine H3 buffer, and the Armalite EA1095 recoil spring. That's what the UBR 2 was designed to run, and it works very, very well. The 0.094" hole is drilled and the spring is ordered. I have one of Clint's CAR-10 heavy buffers that he recommends for 7" tube 308s. It's 5.7oz. Will that work? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 26, 2020 Report Share Posted April 26, 2020 (edited) 1 hour ago, EdgeReady said: The 0.094" hole is drilled and the spring is ordered. I have one of Clint's CAR-10 heavy buffers that he recommends for 7" tube 308s. It's 5.7oz. Will that work? That's a 2.500" buffer. What you're looking for is a 5.4oz 3.250" buffer, and that's either the Armalite AR-10 Carbine buffer, or any old AR15 Carbine H3 buffer. Ditch the spacer that you're using. Don't use it. Run the real shiit, without a spacer in that buttstock assembly. The receiver extension depth on that assembly is 7 5/8" internal depth - itwas specifically designed to run on SR-25s and .308ARs. That spacer is included so people can still run that stock with AR15s. You're not running an AR15 here. Short answer is no - you can't use a 2.500" buffer with that spring. I know the stats say that it will support it - but it doesn't. In theory, it collapses enough to use it - in the real world, you hit coil bind. Run the 3.250" 5.4oz buffer. That stock was made for it. That stock was SPECIFICALLY made for it. My $0.02 on the whole affair. Edited April 26, 2020 by 98Z5V Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 26, 2020 Author Report Share Posted April 26, 2020 Roger that. Will do. Quote Link to comment Share on other sites More sharing options...
EdgeReady Posted April 26, 2020 Author Report Share Posted April 26, 2020 I have the 5.3oz/3.25" buffer and I ordered the Armalite spring from Clint at HeavyBuffers.com. I'm not 100% sure if he has them in stock. I used all my google-fu and that was the ONLY source I could find with an Armalite EA1095 buffer spring that wasn't out of stock or closed down. I'm shut down on this project until I can get the spring. Is anyone aware of any obscure source for an EA-1095? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 26, 2020 Report Share Posted April 26, 2020 1 hour ago, EdgeReady said: I have the 5.3oz/3.25" buffer and I ordered the Armalite spring from Clint at HeavyBuffers.com. I'm not 100% sure if he has them in stock. I used all my google-fu and that was the ONLY source I could find with an Armalite EA1095 buffer spring that wasn't out of stock or closed down. I'm shut down on this project until I can get the spring. Is anyone aware of any obscure source for an EA-1095? That buffer will be fine, man. I searched all the usual places that I get the EA1095s from, and everyone is out of stock. I have a spare EA1095, if things really get bad... The Sprinco Red spring is a good alternate, and was designed for this application. You could pick up a Red spring, run it until the EA1095s come back in stock, and swap it out. If you don't like the Red spring, I'll but it from you for whatever you had to pay for it, plus shipping to me, regardless of round-count that you'd rack up on it. I can always find a use for it around here somewhere. Here it is: https://www.primaryarms.com/sprinco-m4-ar15-carbine-red-extra-power-carbine-buffer-spring Quote Link to comment Share on other sites More sharing options...
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