Suppressors Big POI shift (Off the paper)--ist time supressor [SOLVED]

D

DocRDS

Head Maffs Monkey
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Feb 21, 2012
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#1
Self-moving this to suppressor forum--maybe better spot.

So tried out my new suppressor today and I am baffled (no pun intended). Since the gun had a new brake and chassis I zeroed it first. No issue.

Suppressor on and we couldn't hit the paper or even see the impacts Large (12" x 12" target). I tried to shoot at the edges seeing if I could figure out where the hits were going but after about 6-7 rounds we stopped.

I removed the suppressor and immediately I was back to zero (checked bore first).

I am brand new to the suppressor world--I had the barrel threaded by a highly recommended pro (recommended by local PRS guys). I examined both the rifle bore and the suppressor--I can see no dmg or reason to believe there was a baffle strike. I watched my son shoot a round and it looked like a round came out (bright cone shaped flash at exit of the can).

I took apart the can at home and the locking collar was really hard to get off--don't know if it is fouling or indicative of an issue.

Its a Sandman-S with the muzzle brake mount for 308.

Maybe I attached it wrong--I thought it only went on one way (clockwise with the ratchet drive as far as possible). Need some serious help.

edit: After time with the machinist who threaded my barrel either the QD mount or can is bad. When mounted on the lathe the mount has 0 (or close to 0) runout while the Can has a runout (aka "wobble") of 100 thousandths or more.
 
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#2
How far were you shooting?

Hanging a weight (suppressor) on the end of the barrel can certainly change harmonics and thus POI shifts.

You didn't give any specs on the rifle.....

Perhaps a little more info would help?
 
#3
Apologies, I have very little experience with such things and am more than flustered.

100 yards. Remington VS 26" barrel (Heavy Barrel). Its sitting in a KRG Bravo that I just installed. I had readjusted the scope, and re mounted after getting the barrel threaded and the brake mount timed. It was within 0.5 mils of previous zero (down and left 0.5 each). Rifle was shooting well enough that I could easily dial in my zero with 3 shots (low 0.5 mil, then ID10T error, then zeroed-->mounted supressor).

I took 4-5 shots (I think) then my son took 2-3 as I tried to see impacts and barrel. I couldn't see anything abnormal--but of course I have no clue what to look for.

To start with I was shooting 150gr SP Prvi Partisan to get my zero roughly and try out the supressor before moving to match ammo.
 
#5
I own several cans and see a poi shift with most. A lot of it depends on barrel length/diameter and can weight/baffle design, but all will still land on a 12x12 at 200 yards.
 
#6
I'm not the expert for suppressors but I'll chime in regardless. As stated above you are hanging a big ass weight out on the end of your barrel and it for sure is going to change barrel harmonics.

I don't believe however that is should take you off target by a huge margin. At a minimum you can recheck your setup and make sure you've attached that muzzle brake with rockset or thread lock of some kind. Follow Dead Air's instructions and do a little YouTube research from a RELIABLE channel. Pull the bolt out and look down the barrel from the breech to muzzle with the suppressor mounted. If there is something obvious you know you have a problem. If everything looks good you can look at fine tuning options.

Once you've verified everything is good to go set up wise, move the target to 50 yards and shoot with the suppressor on and off and document the POI shift. As you move back everything should be repeatable. If not its time to seek help from a good smith. Just my $.02 and let us know what you find as we are all here to learn together.
 
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#7
No--same ammo 150gr softpoint. Don't know why i added that extra bit--was using cheap ammo to start (sort of embarassed)--I never switched to the good ammo.

I am wondering if the can was not on as tight as it should be--the dead air has the "Ratchet" clicks and I remember I turned it nearly a full rotation. After cleaning it at home and trying to see if there is anything obvious wrong, it synchs up tight in about 1/3 a turn.

It only took me a couple shots to realize something was very amis--i expected a shift--but to not be able to hit the paper was a shock and why I went to troubleshoot mode immediately. I've had a loose scope before and still been on paper at 100 yards.
 
#8
DocRDS said:
No--same ammo 150gr softpoint. Don't know why i added that extra bit--was using cheap ammo to start (sort of embarassed)--I never switched to the good ammo.

I am wondering if the can was not on as tight as it should be--the dead air has the "Ratchet" clicks and I remember I turned it nearly a full rotation. After cleaning it at home and trying to see if there is anything obvious wrong, it synchs up tight in about 1/3 a turn.
Click to expand...

Is it the Key Mo mount? I believe you should have to give it a couple of twists (not necessarily full rotations but almost a full rotation).
 
#9
DocRDS said:
No--same ammo 150gr softpoint. Don't know why i added that extra bit--was using cheap ammo to start (sort of embarassed)--I never switched to the good ammo.

I am wondering if the can was not on as tight as it should be--the dead air has the "Ratchet" clicks and I remember I turned it nearly a full rotation. After cleaning it at home and trying to see if there is anything obvious wrong, it synchs up tight in about 1/3 a turn.
Click to expand...



As long as you didn't have any baffle strikes / end-cap strikes, you should be fine.

Personally, I have had big POI swings between suppressors as well as suppressed vs. unsuppressed

As stated above - document POI changes!
 
#11
Long Range 338 said:
You should probably watch this video, its pretty insightful.

Click to expand...


Nothing strikes me as off there--i line mine up with the brake at vertical--it clearly is locked in and i can hear the clicks as I twisted it on. I'm asking in a local FB group if anyone has an alignment rod.

My locking ring acted like it was loctited (ok it wasn't stuck like loktite, but it took a full twist of both hands--100% effort). Was a definite change from before. I cleaned up the threads but there was definitly something on them that was binding--and strangely enough it was at the "end" of unscrewing--i could get past the locking teet fine..but the last 2-3 turns was nigh on impossible and you could feel a region where it was binding if that makes sense. it was only about 15 degrees rotation and then it was fine--same spot.

I'm cautiously going to try again at shorter range to help find where the impacts are going. I understood POI shift, but this was beyond anything I'd ever read about.

I did reach out to CS as well at Dead Air as I hear they are pretty solid. Rough go for a 1st suppressor.
 
#12
I just got my Nomad out for the first time today. My KeyMo shipped incomplete so I had to shoot it direct thread but POI shift was maybe an inch straight down. I know the Sandman is heavier but your experience seems extreme. In the end if you didn't have any baffle strikes or major malfunctions just double checking everything and paying attention to the details I would suspect you will resolve it without major difficulty.
 
#13
Install suppressor and remove bolt then look down barrel from the rear.....all you should see is rifling when looking directly in line with bore.....like can isn't even on


Next, simply shoot paper ar 25 yards and see what's going on. It's much easier to diagnose problems at closer range.

Make sure everything it tight as well.

Shoot a group with suppressor on, then remove and shoot at same point of aim as you did with suppressor and that will tell you point of impact (POI) change. Repeat the test a couple times and then measure. Multiply by a factor of 4 and that should be POI shift at 100 yards. Put a target at 100 yards and verify.
 
#14
ugh do i "think" i may have found the issue--if that locking ring is not all they way down the suppressor is a bit loose. (For those not aware the Sandman has a locking ring and a flat washer that prevents you from turning the can more than 360 degrees) My theory is that I didn't have the can tight so that itcould essentially lock up and mate to the cone on the brake for a snug fit. I noticed if i didnt really press down hard and work to get that locking ring down to the lowest point (you have to force the spring washer down to get the "safety teeth" past each other, it can seem like it is on, but still has 1 more turn.

The reason I say this is I remember how far i could twist the supressor before---like I mentioned (I think) i could get a full turn out of it--to the point where the safety teeth were meeting. Now after cleaning it takes less than half a turn to be very snug and the ratchet teeth on the locking ring/safety washer are not even close to meeting.

Back to my local range tomorrow. Kinda feel stupid having to start at 25 yards to sight in a rifle, but here we are.
 
#16
Plus.....once you have it nailed down at 25 yards....jump to 100 ....verify..... then go as far as you're capable and as long as you've verified everything you'll be making hits just like before (but much quieter and MUCH more enjoyable)
 
#19
Something is mighty wrong. Here is the results from today. I finally chased it onto the paper and POI moves with successive shots.

My 5 shot group at the bottom, no can for comparison.

50 yards (no 25 available today). all 168 gr Federal Gold Match. My standard was low as I was chasing the zero all afternoon, but this shows what is happening. My zero with no can is repeatable. (the target before, when i finally pinned down the verticle stringing my group is in the same spot relative to point of aim. I did everything I could to make sure the can was on good and tight--interestingly enough this vertical stringing is repeatable.

target compare.jpg
 
#20
Dead Air reached out to me on another forum. They are taking care of me and I am sending the can in for inspection. Thank you everyone for your ideas and suggestions. POI shift is one thing--but shifting after every shot is something else--not to mention the repeatable vertical shift shot to shot.

Even after all this, there is no indication of a baffle strike or end-cap hit. Time for some pro help!
 
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#21
Removed the action from stock to get the brake removed and there does look to be some cant with the supressor mounted in the opposite direction of bullet shift (bottom of can is barely visible through removed action).

Also kinda torqued at my local stores who are all about selling suppressors and none have tools to help check my alignment (getting my own btw)
 
#22
Just an update and I'll stop posting to my own thread--when removing the brake--the machinist was kind enough to mount the QD mount/brake directly in the lathe and measure runout. The mount itself looked to have no wobble (he was able to measure a little, but not much). Then he mounted the can to the brake--we cranked it down tight and MAN O MAN the wobble was absolutly obvious. over 100 thousandsths in his guage.

So while it is hard to say if it is the mount or the can, one of the two is cause a very large cant in the can alignment.

And again, I don't won't to dog Dead Air because they are absolutely taking care of me. I'm just one of those people that likes to understand how things fail, so if it was me I don't do that any more and now I have a bunch of alignment rods on order.
 
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#23
I’ve been following your thread with interest—please provide an update when you get the replacement parts from DA. Interested to see what kind of POI shift you wind up with.
 
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#24
DocRDS said:
Just an update and I'll stop posting to my own thread--when removing the brake--the machinist was kind enough to mount the QD mount/brake directly in the lathe and measure runout. The mount itself looked to have no wobble (he was able to measure a little, but not much). Then he mounted the can to the brake--we cranked it down tight and MAN O MAN the wobble was absolutly obvious. over 100 thousandsths in his guage.

So while it is hard to say if it is the mount or the can, one of the two is cause a very large cant in the can alignment.

And again, I don't won't to dog Dead Air because they are absolutely taking care of me. I'm just one of those people that likes to understand how things fail, so if it was me I don't do that any more and now I have a bunch of alignment rods on order.
Click to expand...
I'm going with the mount being out of spec. This is becoming a reoccurring problem here lately with DA.
 
#27
DocRDS said:
Something is mighty wrong. Here is the results from today. I finally chased it onto the paper and POI moves with successive shots.

My 5 shot group at the bottom, no can for comparison.

50 yards (no 25 available today). all 168 gr Federal Gold Match. My standard was low as I was chasing the zero all afternoon, but this shows what is happening. My zero with no can is repeatable. (the target before, when i finally pinned down the verticle stringing my group is in the same spot relative to point of aim. I did everything I could to make sure the can was on good and tight--interestingly enough this vertical stringing is repeatable.

View attachment 7245638
Click to expand...
I have a dead air sandman s and the target with my 300 WM looks exactly like this. Does not look like this with 223. What did dead air do to resolve your issue? I need to contact them.
 
#28
Sdotcarter13 said:
I have a dead air sandman s and the target with my 300 WM looks exactly like this. Does not look like this with 223. What did dead air do to resolve your issue? I need to contact them.
Click to expand...
My core was out of alignment. I contacted them and they made it right. According to the rmr they replaced my core. As ticked off as I was, they made it right and its dead nuts accurate now. I posted a stupid small group using it in the bear pit a while back. less than 0.2 MOA.
 
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