EdgeReady

I will retest again and attempt to remove some variables. At this point I don't trust the chronograph readings. I did some research and apparently there's some sorcery regarding chronograph setup and lighting conditions. I probably had it too close to the muzzle and the sunlight conditions were extremely bright. Also, I'm going to ground the rifle next test. I've been shooting from a carpeted platform installed on a Polaris Ranger for that purpose. It permits me to keep my kit mobile and quickly change shooting locations. I'm standing when I shoot, but can base out, lean over the platform, and get onto and into the rifle. While it's pretty stable, especially with a bag and GI socks, it's not like being grounded. I will also shoot from 100yds. If this next test brings results consistent with those to date, I'm going to move on a different barrel. My build goal was portable, accurate, suppressor host. 3 or so MOA is thus far failing in the accuracy category. I had a POF308 with 20" bbl for years, and it consistently shot sub-MOA with FGMM from the same shooting platform.

Are you aware of any reason that a particular system would run lower than expected velocities? The short barrel length is the only factor I'm aware of if you rule out the ammo. The ammo I'm using is well established. The performance of that 14.1 Hanson barrel is also established by others who have used it. I did drill out the gas port, but the gas pressure is controlled with an adjustable block and there appears to be plenty of gas available in the system. The block is only 1 turn from off, which is 75% closure. What other system factors could cause this ammo to be low velocity?

No doubt on the velocities. The highest velocity measured was measured after this test at 2330fps. It was measured at the muzzle. This barrel is consistently printing those groups with three types of 140gr ammo. Unless I become aware of some new sorcery, I'm headed for a different barrel. BA won't honor this one because I've modified it. It's looking like I've got a very short Tomato stake.

I just hit the range to run more tests on the 6.5 CM BA Rifle w/14.1 Hanson bbl. Here's what I did since we last messaged... Thoroughly cleaned chamber/bore and lubed BCG Checked scope & mount torques Re-torqued flash hider using formula to compensate for wrench extension Shot comparison test groups using American Gunner 140gr and FGMM 140gr 200yds Rifle bagged fore & aft 85 degree F Light variable breezes, tree cover either side of range I also chrono-graphed and the velocities seemed low to me Here's a pic of the American Gunner 140gr group, my control group... Here's a pic of the Federal Gold Medal Match 140gr group, my test group... My conclusion remains the same at this point...something is up with this barrel. Thoughts?

I run the FGMM 168/175 in my .308 precision guns and they do run just like you said. This build is a 6.5CM, so Federal offers a 140 Sierra and a 130 Berger in FGMM. I'll try the 140 BTHP.

After boring out gas port, I got everything running, gas tuned, and function tested. I picked up some better ammo (American Gunner) to see what kind of accuracy I get achieve. The American Gunner shot better than the FMJ was using for function testing, but I was underwhelmed with the accuracy to say the least. At 200yds I could only squeeze 2MOA groups from it. The rifle was bagged front and rear, using a Nightforce 3-15NXS for testing. I did have some gusty tailwinds, but I honestly think I could have shot better groups with any AR from my fleet. I'm prepared to just ditch this Hanson barrel and invest in a Criterion, but I think I owe it a bit more effort before going to the nuclear option. After all I've been through with this build, I just don't have confidence in this barrel. Any thoughts?

Gents, Clint's Armalite spring was shipped most rikitik. I installed the spring with the 5.6oz buffer and I achieved functionality. However, after drilling the gas port out to 0.094, it was highly gassed at max gas setting. I had ripped case rims, base marking, and stovepipes until I dialed the gas down. I had to go about 1 full turn from CLOSED to achieve reliable function, bolt lock, with strong 4pm ejection. After single round function testing, I performed multi-round reliability testing. Slow fire or mag dumps, the gun is running well. I retested everything suppressed and the gas block setting end up being only 1 click down for best suppressed function. I'm happy with the way the gun is running now, but I'm concerned that the functional "window" of gas block settings is very small. 1 click more gas brings overgassing with a 1pm ejection or and 1 click less gas brings failure to lock back. There are settings on the gas block that are in-between the detents and provide even more optimal function, but I'm not comfortable adjusting between a detent as it probably won't stay there. I learned long ago never to underestimate the ability of gun fire vibrations to screw stuff up. Question: I filed and polished ramps to eliminate the scarring I was seeing on the casings. Now it does not scar when I load and eject a round, but the scarring is still there when I fire and eject an empty casing. The scarring is two lines on the case neck about 1/4" apart. I thought I would ask before I do anything else with ramps. Thank you all kindly for your assistance with this project. Had I not invested the time in joining this group, I would not be where I'm at with this. I hope that I'll be able to repay the favor in some way. Edge

I lube all my weapon systems with a mixture I learned from the armors at Blackwater which they referred to as "monkey cum". It's a mixture of MIlitec grease thinned by Militec oil to lower it's viscosity. I only place it on mating surfaces or wear points, nowhere else. It stays put even under extreme heat and use, but is thin enough to lubricate well. It lubes well, lasts long, and does not tend to collect debris. I use it in all my rifle and handgun systems, except when in extreme cold conditions when I switch back to a lighter lube. It's always worked well for me, especially once I learned where and how much to use.

Thanks for the compatibility tip, that's just what I needed to scratch my itch to make progress here. I'll gladly purchase a reasonable substitute until the real deal comes in, which will permit me to verify my progress thus far and get some other things sorted out. If you're looking for SpringCo Red, I'll be happy to send it your way. I'm only holding one 308AR system at present so you'll probably need it before I do again.

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?

Roger that. Will do.

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?

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.

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?

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.

+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).

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?

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.

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

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.

Thank you for the kind regards. Looking forward to working with you all.

Hello from central NC. Your group appears to be an active community with an impressive knowledge base regarding 308AR systems. Based on what I've discovered since getting into the 308ar game, I can see the value you bring to the community. I do have a problem I need help with, but I would like to complete some further efforts on my own before asking for help.