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Posted: 2/12/2018 10:39:09 AM EDT
I was shooting my 7” AR-47 yesterday and trying to verify zero at 25 yards. It was a few inches low at 25 with just the flash can on. I expected that height over bore difference as I originally sighted it at 50. I was aiming at the right lower bullseye.
I put my YHM phantom on and shot at the target at left lower bullseye. The rounds are hitting 8+ inches high!  Attached FileI checked for baffle/end cap strikes and see nothing. I was shooting the same GT 7.62x39 for both sides. I have chronoed it without the suppressor at 2k fps my last trip with a buddies chrono. Has anybody seen this dramatic of a poi shift at such a short distance using a suppressor?  Attached File Attached File |
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Posted: 2/12/2018 10:59:26 AM EDT
[#1]
I can't imagine a 24 MOA POI shift just with a can.
What kind of handguard/upper is that? Only think I can think of is somehow red dot is moving with installation of the can. Whether that be that the can moves your rail which moves your dot or something else. Are you making sure to rest your handguard on the shooting rest and not the suppressor? Have you tried shooting bare muzzle? What kind of barrel? Hmm.. This is a tough one. |
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Posted: 2/12/2018 11:15:54 AM EDT
[#2]
I wish I had some sage advice but all I can say is that it does happen. A few guys shooting Lane suppressors on their .458 SOCOMs were/are having huge POI shifts and baffle strikes. They keep enlarging the clearance but are still having problems, and we are talking POI shifts in the feet, not inches.
I hope you can get it figured out but the guy I am mainly thinking about has had to resort to sending his upper and suppressor back to the maker to try and figure things out, and so far, with no fix. |
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Posted: 2/12/2018 11:16:20 AM EDT
[#3]
Quote HistoryQuoted:
I can't imagine a 24 MOA POI shift just with a can. What kind of handguard/upper is that? Only think I can think of is somehow red dot is moving with installation of the can. Whether that be that the can moves your rail which moves your dot or something else. Are you making sure to rest your handguard on the shooting rest and not the suppressor? Have you tried shooting bare muzzle? What kind of barrel? Hmm.. This is a tough one. The rail the optic is mounted to is part of the PRI rail and is torqued properly with a fat wrench as is the PA md ad optic. The weirdest part is that it is repeatable. With the suprresor off it’s on target and when you add the suppressor it hits high. The groups are similar both ways too. I guess I really need to borrow a chrono to see if the extra 8 inches of suppressor is changing the bullet velocity drastically. |
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Posted: 2/12/2018 11:39:30 AM EDT
[#4]
I have a 308 that changes about 7 minute of angle at 100yds. And it runs about 40 fps faster with the suppressor. Other rifles i have some shoot better with it and some shoot better without it. Guess maybe barrel harmonics. I was also told that how true your threads are cut to your bore makes a big poi difference.
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Posted: 2/12/2018 11:43:35 AM EDT
[#5]
Does your YHM can have dramatic POI shifts on any other rifles?
That POI shift equates to .32" at 1 yard 
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Posted: 2/12/2018 11:52:21 AM EDT
[#6]
Quote HistoryQuoted:
Does your YHM can have dramatic POI shifts on any other rifles? That POI shift equates to .32" at 1 yard There has to be something funky going on here. It has me really scratching my head. The AR-47 is my only 7” barrel. I might just dismantle and reassemble it to check everything again. |
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Posted: 2/12/2018 11:58:43 AM EDT
[#7]
Did you happen to try shooting from the rest at different positions on the handguard... ie magwell end resting on the bag.
I wonder if the suppressor is banging the handguard upon firing.... or something is pushing on the suppressor / barrel , enough to move the POI that far. |
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Posted: 2/12/2018 12:02:09 PM EDT
[#8]
Quote HistoryQuoted:
Did you happen to try shooting from the rest at different positions on the handguard... ie magwell end resting on the bag. I wonder if the suppressor is banging the handguard upon firing.... or something is pushing on the suppressor / barrel , enough to move the POI that far. I torqued the handguard when I first assembled it but it might have loosened up without me noticing. Every shot is like a mini concussion grenade with that little barrel. |
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Posted: 2/12/2018 12:09:05 PM EDT
[#9]
Im assuming its a direct thread Phantom? Threads on barrel are just slightly off or the shoulder on barrel. Not enough for a baffle strike, just enough to throw POI off that far.
At least it appears consistent. 
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Posted: 2/12/2018 1:53:39 PM EDT
[#10]
Mystery solved, couldn’t even feel the damn thing when installing the suppressor.
Tl;Dr I’m tarded  Attached File |
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Posted: 2/12/2018 2:24:52 PM EDT
[#11]
Hitting the pin on the bottom? Would make sense.
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Posted: 2/12/2018 2:51:48 PM EDT
[#12]
I'm glad your can survived!
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Posted: 2/12/2018 9:14:04 PM EDT
[#13]
Quote HistoryQuoted:
Mystery solved, couldn’t even feel the damn thing when installing the suppressor. Tl;Dr I’m tarded https://www.AR15.Com/media/mediaFiles/195843/E68CF616-E3F2-406C-86F3-54158C4447F6-449863.JPG |
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Posted: 2/12/2018 10:50:47 PM EDT
[#14]
Quote HistoryQuoted:
Mystery solved, couldn’t even feel the damn thing when installing the suppressor. Tl;Dr I’m tarded https://www.AR15.Com/media/mediaFiles/195843/E68CF616-E3F2-406C-86F3-54158C4447F6-449863.JPG I did something similar once with an Mlok Bipod mount 
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Posted: 2/12/2018 11:00:59 PM EDT
[#15]
Did you shoot it yet without the can hitting that thing? I wanna see some more groups
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Posted: 2/13/2018 3:00:20 AM EDT
[#16]
I had large impact swings. Not that excessive with an SDN6 can but when I used an Omega the swing was hardly noticeable
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Posted: 2/13/2018 3:25:15 PM EDT
[#17]
Could someone clarify? I'm not familiar with AK's or YHM suppressors. In that pic explaining the "pin", is that pin part of the handguard or something in the suppressor as it fits an AK? I'm guessing it's in the handguard. A side pic would probably be self explanatory.
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Posted: 2/13/2018 3:36:52 PM EDT
[#18]
Quote HistoryQuoted:
Could someone clarify? I'm not familiar with AK's or YHM suppressors. In that pic explaining the "pin", is that pin part of the handguard or something in the suppressor as it fits an AK? I'm guessing it's in the handguard. A side pic would probably be self explanatory. Pistol for reference  Attached File |
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