I wanted to share the results of my last range trip with a 12.7" Faxon group buy barrel. I had approximately 60 rounds through the barrel before this trip. The gun is nothing fancy....Spikes upper receiver, Matrix handguard, 12.5" barrel & VG6 6.5 brake, Brownells carrier with a group buy bolt. Lower is an Aero, Rise Armament trigger (I forget which model....3.5lbs) & a Shockwave brace. Scope is a Vortex Crossfire II 3-9. Groups were shot at 100 yards on a set of bags.
The groups shown are American Gunner 123gr and Federal 90gr TNT factory loads. I also shot some Hornady Black 123gr ELD-M and Hornady SST ammo. Most of the groups were just over 1 MOA and the 3 pictures are the best groups from this session. Hopefully it tightens up a bit with some more rounds down the barrel, but overall I can't complain about shooting MOA @ 100 yards with a 12.7" barrel.
Anyone having issues with their 12.5" Faxon? I sent the original back, due to an over abundance of caution, because of the chamber/extension pin issue. The new barrel is holding a solid 4-6 MOA. After 80 rounds, four range sessions, and four different factory ammo types, this is what it does consistently.
[ATTACH=CONFIG]12693[/ATTACH]
My 20" PF Grendel barrel puts all four of the same ammo types into each of those 1" orange dots, with virtually no effort at all.
This Faxon won't shoot.
Anyone else having issues? Right now my barrel is a pretty great 100y shotgun.
tucansam Wrote:Anyone having issues with their 12.5" Faxon? I sent the original back, due to an over abundance of caution, because of the chamber/extension pin issue. The new barrel is holding a solid 4-6 MOA. After 80 rounds, four range sessions, and four different factory ammo types, this is what it does consistently.
[ATTACH=CONFIG]12693[/ATTACH]
My 20" PF Grendel barrel puts all four of the same ammo types into each of those 1" orange dots, with virtually no effort at all.
This Faxon won't shoot.
Anyone else having issues? Right now my barrel is a pretty great 100y shotgun.
After reading some more threads, someone suggested removing muzzle devices. Mine had a YHM 30cal brake, and a 30 cal Phantom suppressor on it. To be fair, I've fired numerous groups both suppressed (heavy weight on the end) and with just the brake) insignificant, but still present, weight). I pulled the brake off, and tomorrow I will shoot with just the bare threads.
I kinda hope the gun doesn't shoot, so I can just scrap the barrel and start over. If it shoots with no muzzle device, I don't know what I'm going to do, considering I have another dozen ARs that all shoot MOA or better with a big heavy suppressor hanging off the end.
Thanks for the suggestions. Same scope, same mount, didn't check the barrel nut, but did pull everything off the barrel. Just threads on the end:
[ATTACH=CONFIG]12715[/ATTACH]
Not quite MOA, but I had two friends with me, and we each quickly shot a hasty 5-round group at the end of a work day. So clearly it was the stuff on the end of the muzzle that was killing accuracy.
Kinda disappointing, since the whole point of a 12" Grendel was to run my suppressor full time and get the same overall length as an 18" gun. My YHM can is all stainless steel, and its heavy. But the QD brake itself is relatively light. So, is it the actual weight of the device on the end of the barrel, or is it perhaps the torque I applied to time the brake, causing axial or radial tension that is affecting the barrel?
This is important because 1. I don't have a thread protector 2. If I have to run the barrel bare it defeats the purpose of buying it threaded and 3. I have a 30 cal Flaming Pig that I could put on it, to at least direct the blast down range, but I'm wondering how that will affect accuracy.
The above groups were factory Hornady AMAX.
Further thoughts on the subject most welcome. I'm really hoping someone comes along and says its a torque issue, and to try again, because when I had the can on the end, even with the weight, the rifle was really really handy.
I don't think it has to do with weight. I'd put the odds at about 95% that your brake and/or can have a burr or something manufactured out of spec. It is possible that the barrel is not threaded concentric with the bore as well I guess.
Try direct threading the suppressor and also try a different muzzle device. It might just be as simple as getting a replacement muzzle brake.
I don't have a direct thread can, only one that attaches via QD to the brake. With the brake alone, or with the can on the brake, I was getting huge groups. Stripped barrel, much smaller groups. I do have several YHM brakes I can test, to see if its one specific brake, and the Flaming Pig. So I guess I need to get to the range and do a lot more testing.
As far as torque, it was suggested in a thread elsewhere. My measurement of torque was "use as few peel washers as necessary and as little force as necessary to time the brake without breaking the upper receiver or fearing the brake will unscrew from the barrel when the can comes off the brake." That's about as scientific as I've been with any of my AR15s.
Tucan, I am not personally a fan of the torque theory, it's more likely to be the common factor of both of the bad-group setups, ie, the brake itself... perhaps along with testing the other cans, what about trying a replacement brake/qd? Also don't know if this is possible for your setup but accuwasher has a set of 24 timing washers with progressively different timing angles (every 15 degrees) built in... that would eliminate any sliding/pinching of those super-thin peel washers (which could also cause some misalignment issues w/ your MB/supp). you only use 1 of the accuwashers with the right timing thickness for your particular gun to align the MB.
"Down the floor, out the door, Go Brandon Go!!!!!"
I do have a different brake I can try. I examined the old brake as carefully as I could, and nothing obvious jumped out at me, defect-wise. But I will try the other brake, brake + can, and the Flaming Pig to see what differences there are.
I don't know anything about your suppressor or break but i called thunder beast on mine and asked if I'm only shooting with the suppressor on do i need to time the muzzle break with the peel washers or can i skip them. They said i didn't need them and it didn't matter the position of my break inside the suppressor. Try the break without the peel washer and a different break.
09-15-2018, 05:19 PM (This post was last modified: 09-15-2018, 05:24 PM by Sixoeight.)
I've never heard of the torque theory but from first glance it sounds like complete snake oil to me. Once it's torqued on the torque on the barrel is gone and I don't think you are going to permanently twist a stainless steel barrel with hand tools. Maybe I am missunderstanding but I don't see torque playing any role. That being said when you are putting on the muzzle brake I would clamp on the barrel and not on the upper as it sounds like you are doing. That's a quick recipe for bending or breaking your upper. Especially if you are securing it by the pins!!!
Even if you put a 5lb muzzle brake on it it shouldn't affect accuracy once you have it zeroed. It's almost certainly one of two things. Best case scenario the brake is a dud and you need a new one. Worst case scenario the threads on the barrel are not concentric with the bore. If the threads are not concentric you basically could only run it with a thread protector. You should be able to check this with a calipers measuring from the bore wall to the outside of threads in several places. The threads will make this a bit tricky because the thread start is not as tall as the rest of the threads. What you are looking for is to determine if the bore is actually not centered with the threads. This could cause the bullet to actually strike or pass to closely to the muzzle brake and/or can which will destroy any possibility of accuracy and easily cause the results you posted.
09-16-2018, 12:26 AM (This post was last modified: 09-17-2018, 06:26 PM by LRRPF52.)
The AMU gunsmiths learned that muzzle device torque does have a noticeable and repeatable effect on grouping, but this is usually fine-tuning an upper.
There's a good video on it I've posted before where the guy explains his process for balancing the torque on the barrel nut and the muzzle device.
That kind of dispersion usually indicates off-centric threads or something wrong with the muzzle device though if the barrel shoots.
With the extra weight of the can on the muzzle, it should tighten the group, not open it up.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
LRRPF52 Wrote:The AMU gunsmiths learned that muzzle device torque does have a noticeable and repeatable effect on grouping, but this is usually fine-tuning an upper.
There's a good vide on it I've posted before where the guy explains his process for balancing the torque on the barrel nut and the muzzle device.
That kind of dispersion usually indicates off-centric threads or something wrong with the muzzle device though if the barrel shoots.
With the extra weight of the can on the muzzle, it should tighten the group, not open it up.
Interesting. I will have to look for that video. But as you said it seems unlikely that that is the problem here. This amount of spread indicates something seriously wrong. I would love to hear those caliper measurements and/or a range report with a new muzzle brake. I suspect you will have some interesting results.
