Suppressors POI Shift

[sic65stang]

Hey guys, just wanted to run something buy you all and see what your thoughts were.

At the range a couple days ago I was testing a new load with a 308 and experienced a large (6MOA) shift with my suppressor on. I dont know if this is just with this load, as it is the first time I used it on this rifle. The group was actually better, just 6min low. Any thought on why this could happen or how to lessen the shift? On my other 308 with this can there is no shift to mention. Thanks for any input. -Bob

 

[sniperdude]

I have a couple 308's that have a 2-3 moa shift , and some with none as well , as long as it is repeatable.

 

[varmint slayer]

Thread on can or QD?

 

[chainring]

So....this was the first time with this suppressor on this rifle? Or the first time for this new load in this rifle...or both?

It's basically impossible to predict how much zero shift you will get with a new can OR a new load, but you can pretty well plan for a shift of some kind. Lighter/higher quality cans less than some, but they are all going to cause a shift of some kind unless you are crazy lucky. Of course a new load can cause a new POI. Shift isn't a problem as long as it's repeatable.

Try the can with your normal ammo, or the new load without the can - eliminate some variables. Sounds like you introduced two new factors, either of which can/will create a POI shift. Threads on the rifle muzzle in good shape and concentric?

 

[sic65stang]

It is a QD can. I worked up the load without the suppressor and this was the first time firing this load through the can. I have fired this rifle with the can before and experienced little to no shift. I am just wondering if there is a specific cause for a certain load to shift and another one not to. The shift is consistent at 6 MOA low. Good group, Just low.

 

[Killswitch Engage]

Sounds to me like your new load maybe on the edge of a node and with the can the harmonic barrel timing is just that much different. It's on a different wave oscillation on the barrel if that makes any sense at all.

 

[Hannibalsnipes]

I think Killswitch is right on the money. adding weight to the end of your barrel is going to effect the barrel harmonics; proportionately related to barrel length. If it's repeatable, then no problem, just write your dope suppressed and unsuppressed down in your data book and you're good to go.

 

[Mike407]

My POI shift ranges from 1-2 MOA depending on barrel and load used. That's between 4 different barrels and calibers. I'm using a pretty heavy .338 DTASS can.

 

[Smokerroller]

Sounds to me like your new load maybe on the edge of a node and with the can the harmonic barrel timing is just that much different. It's on a different wave oscillation on the barrel if that makes any sense at all.

So when someone puts a new can on a rifle for the first time do they typically have to work up a new load? If the groups are there then of course they wouldn't. But how often does a guy have to work up new loads?

 

[Pappasniper]

What can and what barrel might help? I was thinking at first it was a hunting gun, so the weight alone pulled it down. But you said you shot it before with little POI shift. Tell us more.

 

[thumper49802]

pappasniper hit the nail on the head. When i went from no can to my surefire FA762SS i had a .4 mil drop directly at 6 oclock. Still grouped under .5". I also have a 24" schneider and the weight alone is what pulled it down. Can came off and bam! right back to zero. Shorter barrels respond better to suppressors.

 

[Douglas-001]

As a new guy to the NFA game, I just picked up my Phantom direct thread from Jon @ 419 Firearms this past Monday. Tuesday I was at the range. I shot 200 yds. and was 6" low with my loading. 3 min. Dial up on the scope and was pleasantly suprised to generate some outstanding groups. I, too was unsure of what to expect with a 26" bbl. and a tank of a can on the end. It would appear that it is repeatable after another range session today. I so far have 3 different loads out the can and they all seem real close to the same shift. I realize this can change somewhat. The OP states that 6 MOA was his shift. Unless I missed it, he doesn't mention the bbl length or make of can. Just lookng for more info as I will apply this to my own experiences as well. Does it really matter what kind of position you shoot from? Bipod, rest, kitchen window? I would like to add that once you find the load that your rifle really likes, stick with it and generate more of those rounds. Get on the gun and then place a few friendly wagers with your friends. Good luck and good shooting!

Doug

 

[sic65stang]

Can is a Surefire 762SS and the rifle is 24" Rem 700 in a Mcrees chassis. This is my first load for this rifle, but if I remember correctly I have shot this rifle with the can on and off with another bulk loaded ammo and had minimal POI Shift. I will look into it more next time I head out and see if it shifts with other ammo I have.

 

[Killer Spade 13]

AAC Cyclone on my Rem. 700V 26" barrel changed the POI low 6 centimeters at 100 meters. It's quite repeatable when removing and replaceing the suppressor.

 

[Tuukka]

Typically what we have seen in testing is 0-6 MOA at 100 meters.

With most rifle & suppressor combos falling in between 1-3 MOA usually.

The most I recall seeing is with our 20" HK417, that has been c. 6 MOA to 6 o'clock at 100 meters with factory Lapua 167gr Scenar.

Best Regards!

Tuukka Jokinen
Ase Utra sound suppressors

 

[Chucky]

When you put the suppressor on next time with this load grab the suppressor with one hand the lock ring with the other and twist in opposite directions to tighten it down. I have heard of larger shifts with the suppressor if it is not tightened down all the way but a 6 MOA shift on a heavy barrel bolt gun is not normal with our suppressors unless the suppressor is loose or the threads are not concentric to the bore.

 

[azbic]

I've heard the phrase "timed to the rifle/barrel", could this have an effect on POI?

 

[Chucky]

I've heard the phrase "timed to the rifle/barrel", could this have an effect on POI?

No that wouldn't do it. Not is the adapter is threaded concentric to the bore.