Suppressor affecting accuracy - first shot good, next two low

[Poor Knight]

I have a Weatherby Backcountry in .338 RPM with the 18 in barrel. I originally wanted this rifle in this barrel length in order to use a suppressor and still keep the rifle a manageable length and weight. I have a Silencerco Hybrid 46 I was using on this rifle, direct thread attachment. I'm prepping for an Idaho elk hunt in about a month. It's been very hot here in Texas so I sighted the rifle at an indoor 100 yard range about an inch and a half high. The barrel gets hot very quickly - and it was still over 85 degrees in the indoor range - and I thought the larger group size was due to the barrel heating up. I was consistently getting the first round at the top of the sight-in diamond - about 1.5 inches high - and the next two about 2 inches lower. We has a cool front move through this weekend so it only got up in the 90s so I went to a 200 yard outdoor range . I consistently had first round close to the bull and the next 2 rounds 5 to 7 inches lower . I was also checking my Weatherby .280 Ackley at 200 with no issues while letting the .338 RPM cool so I was pretty sure it wasn't me. I was about to pack it in with frustration when I decided to see how it shot without the suppressor. I immediately shot a 1.8 inch 3 shot group at 200 yards, 5 MOA low and 2 MOA left, made the corrections and put 3 in the bull. Anyone else had this kind of problem with a suppressor affecting accuracy?

 

[matthewmt]

Shooting with a harvester evo mine with out a suppressor have been roughly 1.5" high. No deviation in windage,

Sent from my SM-G973U using Tapatalk

 

[willfrye027]

Shoot a 10 shot group and then decide if it’s actually changing POI. 3 shots is not really enough to sort out randomness from true difference. Could also be your scope erector if it’s changing that much at distance..but again need a larger group.

 

[swavescatter]

Check that suppressor is tight. Check action screws. Check that barrel is free floated with suppressor on.

Might just be a bad weight/length combination causing a harmonic? Try adding a silencer wrap or small weight to see if that settles your groups.

 

[wesfromky]

The barrel gets hot very quickly - and it was still over 85 degrees in the indoor range

Mirage? You have a silencer cover?

 

[Tl15]

I run suppressors on 9 of my rifles and all of them shift POI, some of them considerably. But, the shift is always consistent and they group sub MOA just fine. My little Howa carbon stalker in 6.5 Grendel is a .75 MOA 5 shot gun all day with a can hanging off of it. I direct thread on my bolt guns and run a Nomad Ti on my standard chamberings, and a Nomad LT on my magnums. I just sight in suppressed and call it a day. I’ve never had problems with losing zero from removing and remounting a can. I have a Fly 45 inbound and I’m hoping I get similar results on my big bore. I don’t think you’ve got a harmonic problem or you’d be all over the place regardless of where you are in the string. I would love to say it’s some kind of weird first round pop artifact, but that seems like a huge stretch to me. Have you confirmed the can isn’t backing off?

 

[Bluefish]

I have had significant poi shift from a silencer. Usually just lower with silencer. I assume that’s due to the rifle moving less. Changing between shots suggests something is changing. Is the barrel touching something and moving as it warms up? Try the silencer on another rifle, see if that does the same.

 

[ResearchinStuff]

My guess is erratic barrel contract with the stock while the suppressor is attached.

 

[wind gypsy]

I have had barrels with cold bore shift but not nearly to that extent. It seemed to be compounded by suppressor but I didn't have enough data to be positive.

The one thing I wonder is if your barrel was warm enough from prior groups with suppressor to not exhibit the same behavior on the first shots of groups you did without the suppressor.

I don't know if it's just barrels that aren't properly stress relieved or what but I have seen it where a suppressor seems to make them act more erratically. Not acceptable in a short barrel spec'd that way specifically to be used with a suppressor! I'd definitely make sure everything is torqued on right.

 

[wind gypsy]

My guess is erratic barrel contract with the stock while the suppressor is attached.

Small sample size makes it hard to confirm but if it is only on the first shot or 2nd and 3rd shots, that seems weird.

 

[ResearchinStuff]

for sure weird. never seen a 2 moa gun that puts the first shot in a predictable spot either.

 

[TBeach30]

I’m having that issues with my 300win right now. With out the suppressor it shoots roughly a 1.2 MOA group with a 10 shot group. With the suppressor that same load went to a 5MOA group. So is e been trying to rework the load and It’s only getting slightly better but my

 

[Seeknelk]

I'd just say that it seems anytime you hang something on the end of a barrel it's a roll of the dice as to weather it'll shoot the same load well. It has to change barrel harmonics etc and other things I'm to dumb to speak to. But it's probably taking your load out of tune and that's not surprising to me.
I'd try
- tweaking the load ( re work it from bottom up to find a load less " on the edge" or more forgiving.)
- check that you have plenty of clearance( enough to toss a dead cat thru is the recommended amount I hear) in the barrel channel. Are you using a bipod and loading it? This can flex some stocks enough to cause issues and maybe the can affects that?
- make sure the can is tight and stays that way.
Just some thoughts but I'd guess that load is just on the edge of a "node" and the can changes something in a bad way.

 

[TBeach30]

I'd just say that it seems anytime you hang something on the end of a barrel it's a roll of the dice as to weather it'll shoot the same load well. It has to change barrel harmonics etc and other things I'm to dumb to speak to. But it's probably taking your load out of tune and that's not surprising to me.
I'd try
- tweaking the load ( re work it from bottom up to find a load less " on the edge" or more forgiving.)
- check that you have plenty of clearance( enough to toss a dead cat thru is the recommended amount I hear) in the barrel channel. Are you using a bipod and loading it? This can flex some stocks enough to cause issues and maybe the can affects that?
- make sure the can is tight and stays that way.
Just some thoughts but I'd guess that load is just on the edge of a "node" and the can changes something in a bad way.

I just changed powders today and I’m getting more consistent results now. Ya it’s crazy how some rifles can be affected and some won’t be. Like you said if it doesn’t shoot try something new cause that 6-9in dong on the end of you gun is definitely going to change some things

 

[Seeknelk]

Nice! Yeah I think you'll find a good load that just had a moderate poi shift at some point.

 

[Flyjunky]

I just changed powders today and I’m getting more consistent results now. Ya it’s crazy how some rifles can be affected and some won’t be. Like you said if it doesn’t shoot try something new cause that 6-9in dong on the end of you gun is definitely going to change some things

Many times if you’re running close to the edge on your load the extra pressure created by the suppressor will throw the load out of tune.

 

[Poor Knight]

Figured it out - it's a scope issue does the same without the suppressor. Vortex LHT Razor 3-15x42. Sending it back to Vortex. My other one on the .280ai holds zero fine.

 

[ResearchinStuff]

man, should have posted the scope model in the original post, we could have solved that mystery a lot quicker. feel free to add your experience here: https://rokslide.com/forums/threads/vortex-razor-hd-lht-4-5-22x50mm-q-a.246586/

 

[Poor Knight]

Wasn't the scope - it was the rings. I took too much off when I lapped them

 

[Fartrell Cluggins]

Wasn't the scope - it was the rings. I took too much off when I lapped them

When I read the OP, my first thought was what does the gun do without the suppressor. Glad you got it sorted out.