Bravo's 16" build thread

[Bravo Vector Tango]

Post Action:

So this may alludecide to how new I am to shooting longer ranges but I learned today that I could get a rough estimate of range by c9nfirming parallax adjustment. Doing so I figured that the spot I set my target at is closer to 150 yds. I drew a dot by shots I knew I pulled as the shot broke.



A few FTExtracts showed up early, in groups top left and top middle, but with the gas turned down to 4, with 28 to 28.5 grains of xbr she ran great, and shot group top right with 28.0 grains for .790 at 150yd, close to .5 MOA right?



She also ran well with 27 grains of H4895.

Here are the brass from today's hottest rounds of 28.5gr of XBR



I don't see any pressure signs, but wouldn't mind some other opinions.

[Bravo Vector Tango]

Well, good news first. I'm confident that she is precise and as accurate as I am at this point



The bad news is she still isn't feeding right, I tried adding an H buffer and the white SpringCo spring I received. Took her out with 15 rds, and had mostly the same recurring malf.

I brought her home and cleaned the hell out of the entire upper, and I took a fine file, and very gently broke the points down on the extractor. I believe in going slow and strive to remove as little material at a time as I could. I got to a point where brass could rotate free of the claw and head of the extractor without binding.

Rounds also eject just fine manually, and with good force.

So I go out to shoot again today, and shoot the above group in the process of function test, but got a majority of the same extraction malf no matter where my gas was dialed.

At setting 7, with one round chambered from the magazine, and sitting on an empty mag, it would occasionally eject. But not lock back, resulting in brass that looked like this:





And then I would turn the gas up one notch, trying to establish lock back, and it would show over pressure signs. Bolt slipping off the brass, and not picking up the next round or locking back. The brass then starts to look like this:



I'm not sure how opening the gas block one click takes it from 90% function to overpressure stripping bass off the bolt. Is it chamber friction?

I also said to hell with it, and explored the open end settings off the gas block, settings 10-15 and they were all the same failure to extract, but the bolt would lock back.

So at this point I'm open to suggestions. My current plan of action is to perhaps try a different extractor spring/or ing combo. Other than that.... maybe install a different extractor, or bolt all together... maybe Polish the chamber... The rounds are obviously hot enough to work the system and

[Bravo Vector Tango]

necks of the cases that didn't extract, image cap prevented me from putting this in the above post.



Here's one of the worst damage to the rim of the case, you can see on the right side how it is peened over, I can catch my fingernail on it. Also note the frosted look of the case walls, does that mean the chamber is rough?

[COTNTOP]

I have 2 of the AA 16in barrels and running the Hard Use bolt with no problem. I would order one and lube the bolt real good and that might solve things.

[Bravo Vector Tango]

I have 2 of the AA 16in barrels and running the Hard Use bolt with no problem. I would order one and lube the bolt real good and that might solve things.

Definitely a possibility, But I am going to continue to try and getting this bolt to run, I don't think its a lost cause yet, other than extraction, its running fine. there is no damage to the locking surfaces other than standard finish wear that occurs with a phosphate finished bolt.

BTW this is an Underground Tactical 9310AQ bolt.

This is from 27 rounds, and she was cleaned just prior.

[VASCAR2]

I a lot of forum members have radiused the ejector, aids in feeding. Other members noted their ejector springs were very stiff and they trimmed a few coils to improve function. Just curious how stiff your ejector is? If it were me I'd drift the pin out of the ejector and polish the ejector and radius the edge. I don't know if the ejector could be forcing the extractor to loose grip on the rim of the case after firing but might be worth checking. With it ejecting an unfired case I doubt it but something else to consider.

Normally a midlength 16" 6.5 Grendel is not over gassed. If the gas block was not centered over the port correctly it would produce less gas, under gassed and over gassed can exhibit some of the same characteristics. You changed the carbine buffer spring and went to a "white" coded recoil spring. Only make one change at a time, you might try the factory spring with the H-2 buffer. If all else fails I'd try a different gas (non adjustable) block or at least check the location of the adjustable gas block. This might eliminate the possibility it being a gas problem. I would also test the rifle with factory ammunition or at least with new virgin brass to ensure it is not an ammunition problem. If the rifle still didn't function I'd call Alexander Arms for assistance.

[Bravo Vector Tango]

I a lot of forum members have radiused the ejector, aids in feeding. Other members noted their ejector springs were very stiff and they trimmed a few coils to improve function. Just curious how stiff your ejector is? If it were me I'd drift the pin out of the ejector and polish the ejector and radius the edge. I don't know if the ejector could be forcing the extractor to loose grip on the rim of the case after firing but might be worth checking. With it ejecting an unfired case I doubt it but something else to consider.

Normally a midlength 16" 6.5 Grendel is not over gassed. If the gas block was not centered over the port correctly it would produce less gas, under gassed and over gassed can exhibit some of the same characteristics. You changed the carbine buffer spring and went to a "white" coded recoil spring. Only make one change at a time, you might try the factory spring with the H-2 buffer. If all else fails I'd try a different gas (non adjustable) block or at least check the location of the adjustable gas block. This might eliminate the possibility it being a gas problem. If the rifle still didn't function I'd call Alexander Arms for assistance.

Taking the standard carbine spring and buffer is something I had immediately wished I had done when i was in the field with the gun last, and I will be taking them next time i go out. to be clear the current buffer is an H, is an H2 worth exploring?

I do not think the gas block is off center, I have set up these SLR blocks on more than a few guns now, and have never had problems with gas before, to include 5.56, 300BLK and a 308 AR10. - that being said, I am not above pulling the block to confirm, or trying a different, non-adj. block. - the SLR is also stood off from the shoulder enough to compensate for a handguard retaining cap that would typically be there.

I am going to pick up a 1/16th roll pin punch from oregon tool today (if they have one, else brownells), and pull the extractor and see what is going on under there. BTW the ejector spring felt normal, i could easily actuate it by hand with a piece of brass. the brass will rotate starboard and clear the claw and head of the extractor without binding at all. will compare it to some other bolts today to be sure.

So i guess at this point if exploring the internals of the bolt doesn't answer questions, i will procure non-adj. gas block and perhaps an H2 buffer. and go from there.

[danm]

Wow, must be frustrating... Seems you're like me though, solving problems fuels the fire of determination!

[Bravo Vector Tango]

Wow, must be frustrating... Seems you're like me though, solving problems fuels the fire of determination!

Frustrating but also interesting, because its a learning experience, it's not all bad! I really like shooting the damn thing and am highly enocuraged by accuracy results to get it running 100%.

in this video: https://www.youtube.com/watch?v=kYm5UjojDMU the malf i'm experiencing occurs at 2:40


I found that video in http://www.65grendel.com/forum/showt...-Post-23/page2 this thread with a similar, but slightly different problem.

the video and the thread both seem to point to an o-ring if one isn't present, if i pull the extractor and find no o-ring, im going to install one and hope that solves it.

[VASCAR2]

Good to see you checked the ejector already, normally using an adjustable gas block would negate the need for a heavier buffer like the H-2. I guess my memory was off as I thought you had tried a different spring along with a different buffer. I'm sure you can sort this out, just takes patience.

I was just trying to throw out some ideas, never know what others have checked. I had a Friend having strange malfunctions, I noticed the problem was the bolt carrier. He swapped bolt carriers and rifle ran perfect.

[Bravo Vector Tango]

Good to see you checked the ejector already, normally using an adjustable gas block would negate the need for a heavier buffer like the H-2. I guess my memory was off as I thought you had tried a different spring along with a different buffer. I'm sure you can sort this out, just takes patience.

I was just trying to throw out some ideas, never know what others have checked. I had a Friend having strange malfunctions, I noticed the problem was the bolt carrier. He swapped bolt carriers and rifle ran perfect.

Yeah standard buffers have always gotten me there before, because i religiously use adjustable gas.

I did start out with a milspec spring, and a standard carbine buffer, unmarked.

I swapped to a SpringCo White, and an "H" Buffer - seemed to only compound the issue - extraction disappeared almost entirely across the spectrum of gas settings. I made the mistake of not taking the carbine buffer, and milspec spring with me to shoot.

[Bravo Vector Tango]

well sure enough, no O-ring or booster in the 6.5G UT bolt.

I pulled the extractor off of an extra 308 bolt i have, beefy spring, no o-ring or booster.

I pulled the extractor off of a extra 5.56 bolt i had on hand, and bingo, o-ring + booster

I installed both and reassembled the bolt. If I hold a piece of brass flat against the bolt face and let go, it will fling the brass across the room. it was also much tougher to bump the bolt over a piece of brass in the chamber with the FA. so i'm hoping for good results and will report back after I get to shoot more.

Will report back.

[Bravo Vector Tango]

Well fellas, determined tof put this extraction issue to bed, I picked up 2 boxes of hornady factory ammo from bimart and hit the hills after work.

I can report victory, I set the gas to 6, and she ran 100% out of the gate.

I shot a 1.9 rapid fire group of 5 rd, about 1.5 MOA at 150yd.

And another interesting group I wanted to share but my image hosting is acting up, later maybe.

Moral of the story: O-Ring that thing up!

[VASCAR2]

Well glad you got it running BVT, now time to get some serious shooting in!

[Bravo Vector Tango]

Well glad you got it running BVT, now time to get some serious shooting in!

Hello yeah! Time 5o develop some loads and see what she can do.

Thanks to everyone who chimed in and those that put up with my rambling thoughts for 8 pages, haha.