Suppressor POI Shifts

[El Cid]

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.

[El Cid]

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.

[ASH556]

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.

[Apricotshot]

I'll try this with my Halo and my M4S in a few weeks. I know the Halo has a pretty wild shift already.

[Deputy Dan]

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.

[Iraqgunz]

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.

[markm]

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.

[El Cid]

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.

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.

[JasonM]

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.

[markm]

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.