Maybe I’m not using the correct words, but searching for suppressor shift didn’t yield anything but a few anecdotal examples.
Would it be alright to have a thread where we discuss and post examples of POI shift from various cans? I know I was surprised to see the shift for my new Surefire was nothing like what they advertise. And my groups spread out - they claim to tighten them.
I’ll start and if the mods want to kill/close the thread I won’t lose any sleep. Maybe the demand for this information isn’t there.
This is what SF claims for POI shift:
These are my results:
(aiming point w/ can was the small orange dot in the center)
Suppressor: Surefire 556-212DE
Muzzle Device: Surefire FH556-215A
Ammo: Asym 77gr OTM and Southwest Ammo 77gr SMK (each target noted)
Rifle: Lilja M4 Patrolman 16" bbl, 1/8 twist, free-floated handguard
Distance: 100 yards
Rests: Shot from bench with front and rear bags for support.
In both cases the group moved low about 3-4 inches, and left 1-2 inches. The groups with the can also spread instead of staying the same or tightening.
VERY interesting. I’d love to see a whole lot more evidence. Top 3 (SF, AAC, KAC) especially. I don’t have a rifle can, or I’d add to the pile.
I’ll try this with my Halo and my M4S in a few weeks. I know the Halo has a pretty wild shift already.
I also have a -212 and use the 215 FH/suppressor mount on my 6920.
I get about a 3 inch change in POI downward at 100, windage is same as without can… I have only fired M193 through it, when I get time I will try M855, Mk262 etc.
The POI shift is repeatable, so I can live with that.
Instead of questioning or whining about it, why not contact the Surefire suppressor division? If it is not performing to expectations then tell them so they can address it or assist you.
We did a POI shift test a while back with Pappabear’s M4-2000s. Shifts were minimal… about MOA if I recall correctly.
I’ll see if I still have the pic.
I’m hardly whining. If that’s the shift, then I’m good with it as it is consistent. I just figured it would be helpful to have a thread with examples of POI shift for people to reference.
It’s really hard to say anything for certain about shift.
The important (and generally true) thing is that it exactly repeats each time the can is mounted.
What shift you’ll see depends on a ton of factors- the ammo, your guns’ barrel length, barrel profile, freefloat or not, the length, weight, and internal design of the can, any thread-concentricity variance, any manufacturing tolerance variation or stacking on the mounts and the can… and more.
In my experience with many many cans on various hosts over the years, I usually see 1 to 3 MOA of shift… and the direction of that shift seems to be all over the place- it can be any direction from unsuppressed to suppressed.
SF is usually on the smaller end of this, but I’ve seen particular setups have literally no shift and some have 5 or 6 MOA. What I’ve seen have been consistent with brands like SF, KAC, AAC, YHM, OPS, etc.
I DO usually see groups tighten up though, so that part of your testing is interesting.
JasonM makes good points. I can take the same can and get almost no shift on one gun, and 4 MOA shift on another. I’ve actually seen this with my m4-1000 07 model on two different 14.5 guns.
Jason, on a long range rifle with repeatable clicks a significant shift can be accounted for thats true but I’m not pulling a cap off my T-1 micro to adjust it when I put a can on…
FWIW with my SF FA556AR I can’t shoot well enough with an aimpoint to see movement in the groups with or without the can.
I’m by no means upset with the performance. I’m new to cans and trying to figure out what’s normal, and go from there. I do find their photos interesting, but they may have had the rifle in a vise for all I know. That’s why I proposed including all the pertinent rifle data for each person who posts an example. Next time I plan to do a comparison with my 11.5" rifle and see what happens.
I’m not a sniper, so making a perfect head shot isn’t a concern for me. I know even with the shift I can hit a torso size target all day long with the can even if I don’t re-zero.
I’m also curious to know if how I mount it can make a difference. On the 16" gun the 215A hider has 4 separate places that the stub inside can be when mounted. Basically, think 2, 4, 8, and 10 o’clock. I used the 2 o’clock tine/prong yesterday. Perhaps if I use the 8 o’clock the group will move in the opposite (up, right) direction?
Thanks gents!
So the shift is within parameters. That’s what I figured - thanks. As for the groups opening up… it may have been me. I don’t claim to be an amazing shot. I’ll try some other ammo as well in the future.
Agreed that easily adjustable scopes are the best way to deal with it, if it affects you.
I’m not arguing about how to best deal with it, i’m simply stating what my experience has been.
Personally, most of my shooting with cans is not terribly long range and mostly using 4 MOA T-1s, so the big dot combined with the typical plinking ammo practically negates any POI shift in terms of the experience. (sounds kind of similar to your experience)
Definitely worth a shot, you might find one position that has less shift than the others. mark it with a sharpie.
Is the shift in the same direction with both ammo types?
Major manufactures make a product (suppressor) to certain standards of fit/finish/operation/etc… One of these “standards” is (or should be) a measured limited “shift” of POI.
I do not know if they “pressure-test” a suppressor during manufacture to see if anything comes loose…nor if the test for a shift of POI to see if each manufactured suppressor is within any set limits. I believe that during the manufacturer’s initial testing…but more importantly, during demonstrations for the military and Law-Enforcement, they should be able to fire a weapon with and without the suppressor and hit a target out to _____range. I understand "interior-ballistics, and how outsides factors such as wind/temp./altitude play into this.
I believe that a few questions do stand out here which may not be limited to the questions/posting/conversation in this thread so far, but I don’t want to get off topic, nor stir things up.
1: Can someone list down the major reason why there could be a shift of POI other than saying "it could be for any number of reason such as ___, ___, ___, etc…and possibly a little insight as to why for each item.
2: If you have a “shift” that repeats itself…has anyone addressed this issue to a specific manufacturer, and have they corrected that “shift” with any additional work to the suppressor (?)…What was the outcome of contacting a manufacturer (what did they tell you)(?)…Did the weapon have to be sent to them for fitment, etc. (?).
2: If it is ammo related, can the manufacture suggest a specific loading (IE: Bullet-weight and loading FPS/bullet-speed using __length barrel w/"-twist…such as to mimic what they used for testing, and use during demonstrations so they could show minimal “shift” of POI .)…or state the barrel-length/twist-rate and loading so that a new purchaser of their suppressor can limit his/her shift of POI when attaching their suppressor (?).
…and What has any manufacturer told you (?).
3: Are there any “points” as to what a person can do to bring down the amount of “shift” , or move the “POI” without changing the settings to their optics when using a suppressor (?).
Regards, RichardS in MI.
US Army, Retired.
PS: I am awaiting Transfer-approval of a new suppressor for my 5.56x45mm rifle…so any good information will help.
The biggest answer to all your questions is that the barrel of the host weapon is the biggest variable. The same suppressor mounted to two different barrels will likely have different POI shifts. That’s why the smart suppressor company has stated shift to be “minimal” and “repeatable”, while the over-charging, marketing-driven suppressor company has used “minimal POI shift” as a marketing tool, while obviously and as the evidence in this thread shows, that is not always the case, nor can it be guaranteed. If barrel harmonics play a large enough role that benchrest shooters are willing to hang weights off their barrels, what sort role do you think hanging a 1lb + suppressor off the end is going to have?
Bottom line is it doesn’t effect combat effective accuracy. If you want precision, thread the suppressor on your gun, get your dope, and never take the thing off again.
Perfect answer
Legit concerns, but you are kind of missing the point in that there are so many factors that affect potential POI shift with a can that they cannot all be anticipated or counteracted.
Unless a manufacturer has your exact gun (not an identical setup, I mean your actual gun) including the ammo you will shoot, they cannot determine the exact shift you will get with your can (or even be 100% of a range you might see).
They can (and some do) test for shift and function on test guns to ensure a general baseline performance, but that doesn’t always translate into what you will experience.
Specific to your questions-
Major factor is the barrel - combination of length, profile, and concentricity of threading.
Any shift will exactly repeat itself with a good can. Getting a mount or can tuned to a particular gun is not done (as far as i’ve seen), since any “tuning” is fairly worthless if the gun or mount or ammo is changed…
2B. No. Again, it’s the combo of all these variables that determine what your particular setup will experience. A general rule is- the shorter and heavier your barrel is, the less POI will be affected (but again, this doesn’t always hold true)
In terms of real world usage, it’s not as much of a concern. if you are bullseye shooting, then leave your can on and zero that way. If you are doing typical carbine shooting at man size targets out to say 100M, a couple MOA shift probably won’t be noticeable.
50 yards from a bench.
Surefire 556-212 with -212 mount
Noveske 14.5" CHF w/switchblock
Vltor VIS upper
MK318 SOST
Aimpoint M4S
POI matches POA with suppressor attached. Shift is exactly 4MOA. Zero is repeatable without any visualization of zero-shift using this ammunition from this weapon. Group size suppressed vs. unsuppressed is not statistically different.
