It came up in another thread: POI shifts associated with the attachment of a silencer. It's a phenomenon I have been meaning to look into, as it applies to my silencer inventory. I don't consider it terribly important, as I zero my guns with a silencer attached, and that gun won't be shot in the future without said silencer. But, as a silencer nerd, I want to investigate it all the same. I made some time yesterday, and began a relatively informal evaluation. The results are...
SAN Sig 553R
Aimpoint CompML3 w/ 3x mag
AAC 51-tooth hider
4" low with can
10.5" AR15 w/ SupArms piston kit
AAC 51-tooth hider
4" low, 2" right with can
SAN Sig 553
Smith Enterprises Vortex hider
4" right with can
4" low, 3" left with can
Colt 933 11.5" AR15
2" high with can
4" high, 3" right with can
I did not shoot groups, in the interest of ammo conservation. I shot from the prone, off a backpack, at 100m. One shot unsuppressed; one shot suppressed. If I felt like I made a shitty shot, I re-engaged.
I think it's interesting to note that a vertical shift in the downward direction is perhaps unavoidable. Taking that into consideration, the Griffin can likely had the most significant shift, even though it didn't budge in a vertical direction on paper. It also bears mentioning that this is no indication of the shift performance of any of these cans, as the host plays a not-insignificant role in shift effects; things like muzzle thread tolerances, bore concentricity relative to the muzzle thread OD, muzzle face and shoulder, barrel length and profile, etc. The 553, for example, has a very small shoulder, and the Vortex hider actually seats against the muzzle face, which I prefer, on that particular gun. Also, the barrel length and profile on the 553 ought to promote less of a vertical shift; the NATO cans were not able to take advantage of that though. The NATO-mountable cans did not perform as well as the AAC 51T interface, which I suppose is to be expected. However, it's worth noting that the NATO attachments can be "clocked" to varying degrees. The Griffin can be locked against either flat of the device, and the HALO, when utilizing the Vortex as a mount, can be clocked at each of the flash hider prongs. That being said, a user can pick the location with the least shift, and maker sure to mount it the same after any future removal. Unfortunately, due to the proximity of the gas valve on the 553, I am limited to only one position.
I intend to update this information, as I perform the same "test" on other guns, with these, and other silencers. For me, this data is of little consequence, but it is certainly worth knowing, in the event a silencer fails in some way, and I am forced to shoot without it.This message has been edited. Last edited by: KSGM,
I am always curious when someone claims that he has no POI shift regardless of whether a suppressor is attached to a rifle. I would expect some shift to be more common than not. I do shoot groups with and without and note the results. My (single) Thunder Beast suppressor has no apparent effect on precision, but the POI is always lower, and sometimes shifted horizontally a bit.
“Wise men talk because they have something to say; fools, because they have to say something.”
Interesting observations. I tend to see more POI shifts with QD mounts vs direct thread.
I have transitioned away from AAC 51T and standardized to YHM QD. I just received my AAC SDN and SD from ECCO machine--haven't brought them to the range yet.
I see no reason to measure POI shift for a direct-thread. As you said, it is likely less to begin with, and the odds of you using a weapon equipped with one in an unsuppressed condition are that much slimmer. I know I need a strap wrench and a proper fixture to hold the barrel or receiver, in order to remove my direct-thread silencers. I wouldn't be able to do that in the field. Had I known how addicted to silencers I'd eventually become, I would have gotten more direct-thread cans sooner. I bought an older Gemtech Trek model just the other day; I am glad some folks still have new-old-stock of those silencers. I am hot for a Griffin GP5 as well.
|Green grass and |
I have a direct T Griffin GP7. There is definitely a poi shift when I shoot with it vs without it on my large center fire rifles. Btw, I just hand tighten it. Remove by hand also. Shoots fine.
"Practice like you want to play in the game"
Depends on the host, as acknowledged above. Logic says less threads and devices in between the gun and the can reduce possible problems. But, hell, if the muzzle has something about it that would cause a left shift, but the device and silencer mating create a cancelling right shift, then voila: no perceived shift. anything is possible.
What kind of rifles do you use the GP7 on? Hard-use semi-autos, or bolt guns and semi-auto precision with lower fire rates? What kind of POI shift do you experience?
I am not wanting a GP5 because I think it'll have minimal POI shift. I am wanting it because it's the only aesthetically pleasing pinnable direct-thread that I can find.
|Green grass and |
Bolt action large caliber CF rifle's. As far a poi I posted about it in this section a year or more ago and cannot remember now. Six inches low and right a couple inches sticks in my mind but that could be off. But it was significant. Griffin makes good equip. I do prefer my YHM though. But not by much.
"Practice like you want to play in the game"
I would be comfortable with hand-tight on a slower rate of fire weapon as well. On something that get's used a bit more vigorously, I prefer the strap wrench, if the can doesn't have wrench flats.
The low shift is to be expected, it seems.
I don't have my notes handy, but my main AR's POI drops about 1.5 minutes with the can on. No horizontal shift. I use a YHM QD flashhider mount.
1.5" is pretty damn good, considering my results so far, and the comments of others.
For now, I maintain that shift has a lot more to do with the gun than it does with the silencer, and the mount interface is somewhere in between. Even an interface like the NATO mating used on the HALO or M4SD would have minimal shift and be repeatable if all muzzles and muzzle devices were 100% consistent and held to high tolerances.
OP updated to include Colt 933. Weird results here. All shifts were high, which is the opposite of what I'd expect. Griffin has another poor performance. The old HALO scores a big win with no shift! Goes to show that it's more about the gun than the can.
I'm a bit confused on the methodology and test conditions. What ammo type are we talking? Because if its most of the common stuff let's say for the moment 2-3MOA milspec stuff. then with one shot groups you know exactly nothing on these measurements. really. add to that the size of the aiming dot which is material and the exact amount of the shift is a bit iffy.
“So in war, the way is to avoid what is strong, and strike at what is weak.”
Those are valid concerns, hrcjon. This is far from being as scientific as it ought to be. My available time is limited, as is my willingness to use five times as much ammo. It is the same M193 ammo I always use. For what it's worth, I have shot 8-inch groups at 500m with it, using an aimpoint with 3x magnifier, resting off a backpack, with a 10" gun. That being said, there is certainly still room for an inch or so of variation at 100m, and that's admittedly no small potatoes. For now, I think the conditions are such that it serves to give a general idea of the effects of POI shift. The whole thing is really merely trivial, as I don't think it gives any true indication of the quality of a can, in regards to shift; not because of my conditions, but because it is so influenced by the host weapon.
Also, you may be interested to know that I tried the "test" with the G36 as well, as I was curious about the OSS and the G36C muzzle's mating with the OSS device. Couldn't get any usable data. Firstly, because I goofed-up and forgot that damn can tightens itself, so I couldn't readily remove it after zeroing the optic with the silencer attached; secondly because I am starting to think the top rail is highly questionable, in terms of rigidity. It seems as though the plastic top rails on the C and K models are really meant for CQB optics being used at CQB distances ONLY. This sucks, because I have grown fond of the gun, and I'd like to properly equip it for a general application. An aluminum top rail is in order.
I have an AAC Ti-Rant .45 suppressor that I use on my 9mm suppressed pistols. The Ti-Rant suppressor allows me to rotate it while fixed securely to the threaded barrel. By playing with the different positions (I believe there are 6) I was able to find one that pretty much negated any offset when running the suppressor. When used with a different pistol I have to change the position to get similar results. There's definitely a variance between different pistol setups as the Glock is dead on with and without the suppressor whereas my suppressed P229 will always be off by a little bit one way or the other depending on which notch the suppressor is set in.
|It's pronounced just |
the way it's spelled
I’m also of the opinion it is the gun, not the suppressor. As an example, I have a 45ACP Osprey that makes no changes to POI on a Sig 1911, but moves the POI on a CMMG 45ACP 3-4 inches lower, both at the same handgun distance.
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