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Posted: 2/27/2017 9:55:57 AM EDT
[#1]
I know you gave a general idea of what ammo that you used, but can you list what you specifically used? Even the brand.
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Posted: 2/27/2017 9:56:57 AM EDT
[#2]
Looks like you checked most of the likely culprits so, not sure what more you can do other than checking the barrel nut. I went through the same exact thing with one of my rifles and it turned out to be the barrel nut being loose. I swapped a rail and it ran fine for a few hundred rounds but, ended up working it's way loose over time.
Have you cleaned the bore thoroughly yet? Also, there have been a few reports regarding BCM and expected accuracy versus expectations. I know there was a thread not too long ago where a member was getting similar results from one of his. |
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Posted: 2/27/2017 11:07:54 AM EDT
[#3]
What kind of groups did it produce before you shelved it for a year?
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Posted: 2/27/2017 11:31:48 AM EDT
[#4]
Quote HistoryQuoted:
I know you gave a general idea of what ammo that you used, but can you list what you specifically used? Even the brand. Quote HistoryQuoted:
I know you gave a general idea of what ammo that you used, but can you list what you specifically used? Even the brand. PMC X-TAC (55gr) - best grouping Federal XM855 (62gr) CBC (mk262 clone) - 77gr IMI RazorCore (77gr) Blackhills - 77gr (OTM and TMK); 62gr TSX, 50gr TSX Barnes Precision Match - 85 gr Hornady - 55 and 62 gr Quoted:
Have you cleaned the bore thoroughly yet? Also, there have been a few reports regarding BCM and expected accuracy versus expectations. I know there was a thread not too long ago where a member was getting similar results from one of his. Bore has been thoroughly cleaned. Used both a brush and Hoppes 9 bore clearer until I got a clean patch. Quoted:
What kind of groups did it produce before you shelved it for a year? I never logged groups for this upper/barrel. In hindsight this should have been done. It's life up until recently was just an eotech and mostly used on steel. |
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Posted: 2/27/2017 11:44:38 AM EDT
[#5]
How is your shooting condition and setup?
Did you use a shooting sled/rest with a sturdy table w/ your arms/elbows resting on table? What magnification is the scope? If so, you should be definitely check the barrel nut since you said you already checked everything else including the optic mounts. With so many ammo selections that you already tried... you should be at least be getting ~2MOA, especially the CBC 77 OTM and BH 77 OTM From my experience those are capable of consistent 1.25MOA 10rd groups at 100 yards and about 1.5MOA 10rd groups at 200 yards, using my KAC Mod1 w/ its LW CL CHF 16" barrel |
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Posted: 2/27/2017 12:24:30 PM EDT
[#6]
Quote HistoryQuoted:
How is your shooting condition and setup? Did you use a shooting sled/rest with a sturdy table w/ your arms/elbows resting on table? What magnification is the scope? Multiple scopes were used: Trijicon Accupower 1-4x (AP mount), Accupoint 2.5-10x (Larue mount), Nightforce 5-25x (Larue mount) KAC irons were also used Shots were taken from: Bench (bagged front and rear; vise; bipod front, bagged rear) Prone (bagged front and rear; bipod front/bagged rear) Standing un-supported If so, you should be definitely check the barrel nut since you said you already checked everything else including the optic mounts. With so many ammo selections that you already tried... you should be at least be getting ~2MOA, especially the CBC 77 OTM and BH 77 OTM From my experience those are capable of consistent 1.25MOA 10rd groups at 100 yards and about 1.5MOA 10rd groups at 200 yards, using my KAC Mod1 w/ its LW CL CHF 16" barrel Agreed with you on the ammo (albeit 5 shot groupings). |
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Posted: 2/27/2017 12:37:52 PM EDT
[#7]
Quote HistoryQuoted:
PMC X-TAC (55gr) - best grouping Federal XM855 (62gr) CBC (mk262 clone) - 77gr IMI RazorCore (77gr) Blackhills - 77gr (OTM and TMK); 62gr TSX, 50gr TSX Barnes Precision Match - 85 gr Hornady - 55 and 62 gr Bore has been thoroughly cleaned. Used both a brush and Hoppes 9 bore clearer until I got a clean patch. Not that that is guaranteed to help but... I assume you have a muzzle device, have you removed it to clean carbon build up from the crown? |
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Posted: 2/27/2017 12:56:18 PM EDT
[#8]
Quote HistoryQuoted:
That is not thoroughly cleaned. Hoppes#9 doesn't remove copper. You are about 3k rounds over due for copper cleaning. Not that that is guaranteed to help but... I assume you have a muzzle device, have you removed it to clean carbon build up from the crown? Pinned and welded. |
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Posted: 2/27/2017 1:02:43 PM EDT
[#9]
Quote HistoryQuoted:
Pinned and welded. I use Hoppes Elite Copper Terminator, to clean my precision barrels of copper fouling. I would suggest you look for something similar. Then maybe try to see if the crown is clean and free of carbon build up. |
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Posted: 2/27/2017 1:23:51 PM EDT
[#10]
Quote HistoryQuoted:
Well that doesn't help. Who knows what that did to the bore. If carbon builds up around the crown and chunks break off it may simulate a damaged crown. I use Hoppes Elite Copper Terminator, to clean my precision barrels of copper fouling. I would suggest you look for something similar. Then maybe try to see if the crown is clean and free of carbon build up. I've been using Hoppes Bench Rest 9 Copper Gun Bore Cleaner. I ordered some sweets 7.62 solvent to give that a try as well. |
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Posted: 2/27/2017 1:26:15 PM EDT
[#11]
It might not be related to OP's problem with accuracy, but my most shot rifles, both are the KAC Mod1, are still accurate after multiple thousands of rounds w/o cleaning or lube.
I only cleaned them twice or maybe three times through their 12.5k and 13.6k round count. Like OP, I've only used Hoppe's 9 for the barrel, and I use bore snake with patches. |
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Posted: 2/27/2017 1:27:56 PM EDT
[#12]
Quote HistoryQuoted:
Quote HistoryQuoted:
Quoted:
How is your shooting condition and setup? Did you use a shooting sled/rest with a sturdy table w/ your arms/elbows resting on table? What magnification is the scope? Multiple scopes were used: Trijicon Accupower 1-4x (AP mount), Accupoint 2.5-10x (Larue mount), Nightforce 5-25x (Larue mount) KAC irons were also used Shots were taken from: Bench (bagged front and rear; vise; bipod front, bagged rear) Prone (bagged front and rear; bipod front/bagged rear) Standing un-supported If so, you should be definitely check the barrel nut since you said you already checked everything else including the optic mounts. With so many ammo selections that you already tried... you should be at least be getting ~2MOA, especially the CBC 77 OTM and BH 77 OTM From my experience those are capable of consistent 1.25MOA 10rd groups at 100 yards and about 1.5MOA 10rd groups at 200 yards, using my KAC Mod1 w/ its LW CL CHF 16" barrel Agreed with you on the ammo (albeit 5 shot groupings). Well, seems like you really did tried almost everything.... I guess, as you posted in your OP, check the barrel nut tightness. |
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Posted: 2/27/2017 7:15:28 PM EDT
[#13]
The barrel needs Butch's Bore Shine or Barnes C-10. Those are good copper removers.
Apparently we don't have a base line on accuracy from before it was put away. It is fairly well-known that 1:7 twist BCM chrome lined barrels are great for durability in a fighting rifle, but have never been considered to be MOA or close to MOA capable. Most seem to shoot about 2 to 2.5 MOA, about what you might expect with M855 or M193, and don't seem to do much better with more accurate ammo. It's a battle rifle barrel. A good one for that purpose, but that may be all it's going to do. Just enjoy it for what it is. |
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Posted: 2/27/2017 8:53:03 PM EDT
[#14]
Its a clone of a mil-spec barrel with 4k rounds on it....I don't personally think anything is wrong. I think that's just how it groups.
I've been through a few BCM SOCOM barrels and they all grouped 2-3 MOA. My Colt SOCOM barrels group 1-2 MOA. Both of which are acceptable for what the barrel is intended to do. Its a combat barrel, not made for precision |
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Posted: 2/28/2017 5:08:49 PM EDT
[#15]
It's definitely the barrel nut. If you grab the rail in one hand and apply pressure to muzzle with the other the barrel actually moves inside the handguard.
I've never had a barrel nut "back" off before. How often do you guys check the torque on your barrel nuts?? |
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Posted: 2/28/2017 5:12:52 PM EDT
[#16]
Remove the rail and check the torque on the nut. All barrels flex a little. How much distance does the barrel travel when you put pressure on it?
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Posted: 2/28/2017 5:17:30 PM EDT
[#17]
Quote HistoryQuoted:
Remove the rail and check the torque on the nut. All barrels flex a little. How much distance does the barrel travel when you put pressure on it? I had to borrow a wrench from a co-worker so I haven't checked the torque yet. The barrel moves 1/4-1/2" when you put pressure on it. |
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Posted: 2/28/2017 8:35:13 PM EDT
[#18]
Holy shit, 1/4"-1/2" !? ... that is a lot of movement
My LW 16" moves 1/16" ~ 3/32" at the muzzle end if I really put some pressure on it. Torque it to the right spec, and try to do shoot some groups with it. I've never experience a loose barrel nut before. Most of my AR are KAC, which has a different system and apparently they put blue loctite on the threads. Also have 3 Colts and 1 PSA, no issues. |
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Posted: 2/28/2017 8:45:55 PM EDT
[#19]
Quote HistoryQuoted:
I had to borrow a wrench from a co-worker so I haven't checked the torque yet. The barrel moves 1/4-1/2" when you put pressure on it. |
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Posted: 2/28/2017 9:16:17 PM EDT
[#20]
Who installed the rail? Was it from BCM with the ris or installed later? BCM is not exactly known for loose or under-torqued barrel nuts, usually they are ape tight. Yours may be loose, but that may just be what that specific barrel is capable of.
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Posted: 2/28/2017 9:18:23 PM EDT
[#21]
I had to send my BCM back. From the bench with a Caldwell lead sled I was getting 5 inch groups at 100 yards. I tried sand bags, wood, arm, two different shooters...nothing. This rifle is free floated with a MI rail straight from BCM. It took me forever to get in touch with BCM, I was not happy. They would not return calls and it took a few emails and two weeks to finally get it sent back. I told them it was either crown damage or over torqued barrel nut.
After a few weeks of them having the rifle I emailed and was told the rifle was fixed and it was on its way back. I asked what was fixed and never heard back. It is going to be hard for me to purchase from them again. Hope you have better results. |
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Posted: 2/28/2017 10:39:56 PM EDT
[#22]
Quote HistoryQuoted:
Are you sure it's all barrel flex and you aren't flexing the rail along with it? Quote HistoryQuoted:
Are you sure it's all barrel flex and you aren't flexing the rail along with it? Barrel flex, rail is solid. Quoted:
Who installed the rail? Was it from BCM with the ris or installed later? BCM is not exactly known for loose or under-torqued barrel nuts, usually they are ape tight. Yours may be loose, but that may just be what that specific barrel is capable of. BCM assembled the upper. Quoted:
I had to send my BCM back.....<snip> Hope you have better results. Well, I broke the rail down and checked the torque on the barrel nut... DD says to torque to 50#, which I tried and it didn't move. Looks like the barrel nut wasn't the problem after all. When you apply a lateral force on the barrel you can actually see the barrel extension moving inside the upper receiver. Looks like I'm going to have to pull everything and shim it. |
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Posted: 2/28/2017 10:44:31 PM EDT
[#23]
To get completely off topic... What kind of accuracy should I expect out of this barrel? Being that I'm completely stripping this down I would hate to waste my time assembling all of it back together only to be disappointed again.
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Posted: 2/28/2017 10:56:17 PM EDT
[#24]
Quote HistoryQuoted:
To get completely off topic... What kind of accuracy should I expect out of this barrel? Being that I'm completely stripping this down I would hate to waste my time assembling all of it back together only to disappointed again. Most people are reporting 2-2.5 MOA with BCM barrels |
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Posted: 2/28/2017 10:57:05 PM EDT
[#25]
Quote HistoryQuoted:
To get completely off topic... What kind of accuracy should I expect out of this barrel? Being that I'm completely stripping this down I would hate to waste my time assembling all of it back together only to disappointed again. Around 1.5 with match ammo I'd guess. I've seen a few people get really lucky but it isn't the norm. |
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