Help requested!! Weird grouping with 6.5 Creedmoor (advice/ guidance welcome)

[Puddle]

So, the weirdness only happens with that particular suppressor. How different is it from the other suppressor? Length, weight? No damage on the suppressor?

Yup. He introduced one major variable. He swapped out the can.

Put the other can back on and see what happens...

 

[Corey0372]

Yup. He introduced one major variable. He swapped out the can.

Put the other can back on and see what happens...

The new can IS the variable, I just want to know why you know? I GOTS TO KNOW

 

[Inline6]

Most of the time mirage will have me impacting high though, was this not the case for you?

Mirage from the ground or the can?

Honestly I don't remember what the impacts were. I knew the mirage from the can caused it and I ordered covers that day. That was my Kcan on a 300BO SBR. So I'm sure it heated up faster, it had never happened before. It was a colder day that go and it was crazy how fast it happened. Have had no issues after the covers were installed. Shooting up to 20 round strings in a comp setting which means 90 seconds.

 

[dchum]

It just happens. Every rifle is unique, every suppressor is unique. When you put them together is can lead to confusing results. Your YHM works flawlessly just use that.

 

[Inline6]

It just happens. Every rifle is unique, every suppressor is unique. When you put them together is can lead to confusing results. Your YHM works flawlessly just use that.

K cans are nice to hunt with, they are not the quietest. If I were the OP I would want to know too.

 

[Corey0372]

Mirage from the ground or the can?

Honestly I don't remember what the impacts were. I knew the mirage from the can caused it and I ordered covers that day. That was my Kcan on a 300BO SBR. So I'm sure it heated up faster, it had never happened before. It was a colder day that go and it was crazy how fast it happened. Have had no issues after the covers were installed. Shooting up to 20 round strings in a comp setting which means 90 seconds.

Interesting, I'll order a cover, and check it out, they're definitely nice to have regardless, it was chilly out Saturday... like 36 or so

 

[Inline6]

The new can IS the variable, I just want to know why you know? I GOTS TO KNOW

So do this take a cotton hand towel wrap the suppressor and shoot 5 rounds. If it works better buy a proper cover. If it doesn't you have something else to look at. .02

 

[Corey0372]

K cans are nice to hunt with, they are not the quietest. If I were the OP I would want to know too.

That and since the HMR is already dummy long... and gonna primarily be a bench type gun.. I figured put the longer can on it

 

[Corey0372]

So do this take a cotton hand towel wrap the suppressor and shoot 5 rounds. If it works better buy a proper cover. If it doesn't you have something else to look at. .02

ill probably order a cover tonight

 

[Inline6]

That and since the HMR is already dummy long... and gonna primarily be a bench type gun.. I figured put the longer can on it

My comp rifle has a 26" barrel + a K can and is close to 20#s. It get ran on everything but a bench. Don't be afraid to shoot off barricades and props with it.

 

[Inline6]

ill probably order a cover tonight

Who's are you thinking?

 

[Corey0372]

My comp rifle has a 26" barrel + a K can and is close to 20#s. It get ran on everything but a bench. Don't be afraid to shoot off barricades and props with it.

oh for sure, ive done it with MK 13 Mod 7s, its a HEFT, but heavy guns shoot good man

 

[Corey0372]

Who's are you thinking?

dont know, know any good small companies making them to support?

 

[NDWoods]

dont know, know any good small companies making them to support?

Cole-Tac
Used their stuff for years and met them at an overnight stay in South Africa. Good people.

 

[Inline6]

I have Cole Tac, Precision Underground, and rifles only.

All little guys, all American

 

[Corey0372]

Okay, so gonna order one, any other ideas other than that? its just such a consistent oddity, never seen anything like it, talked to 2 ultra nerdy sniper buddies and they didnt have much of a clue either

 

[Inline6]

Okay, so gonna order one, any other ideas other than that? its just such a consistent oddity, never seen anything like it, talked to 2 ultra nerdy sniper buddies and they didnt have much of a clue either

What we know - the rifle shoots well with no can. The rifle shoots well with the K can. The rifle shoots tight groups with the bigger can the impacts move as the can heats up.

So we take the clues we are given. My first culprit would be mirage off the can. BTW different scopes and different power ranges pick it up differently (might be why you have not seen the effects on different rifles).

Once covered and tested, we either fixed the problem or we go to the next step.

If it makes you feel any better, I'm one of the nerdy types too. If my shooting partner had not told me what happened to him with his cans. I would have been scratching my head too. When it happened, I remembered our conversation.

 

[HookMeUpII]

Take the can off..... and I wouldnt have the issue

I think you answered your own question here. I don't know much about cans because they are illegal in the communist republic in which I reside but...sounds like you found your variable.

 

[BourbonTrail]

I did this...

did about 4 separate iterations of the "drill" for lack of a better term

With the can on the first 2 shots would be basically point of aim, point of impact (minus the .2 right which is just bc im using a different can than last time)

3rd shot would be .5 low

4th, 5th, and consecutive shots would group nice and tight .8 low from the initial first 2 shots


I would let everything cool down for a few minutes... then run the test again with the same results



Take the can off..... and I wouldnt have the issue

If you were shooting at 36 degrees F, I would say that barrel harmonics are playing a role. The barrel is stiffer when it is cold. The mirage may also be an issue in that cold of weather, but after eliminating that, I would look into barrel harmonics. The YHM weighs 9 oz and is 5.6 inches long, but the AAC is 23 oz and 9 inches long. Thats a lot of moment arm difference.

 

[Bob Nelson 35Whelen]

I have heard of a string of shots like you describe as the group "walking". The culprit may be the barrel rubbing against the stock in the barrel channel. As the barrel heats up and expands it changes the pressure against the barrel. If the barrel is not completely free floated then thats a good place to start. Also bed the action if that hasn't been done.
I would also suggest allowing the barrel to cool a lot longer after 3 rds fired. The smaller the barrel the more likely heat/expansion may affect groups.
Like mentioned above cleaning needs to be considered. I had one rifle in a .300 WSM. After cleaning it was a honest .35 MOA rifle. After 9 rds of TTSX's it was a 1.5-2 MOA gun! An extreme example but the truth non the less. Bore tech is a great cleaner and will work well for you. A little experimenting should tell you how often you need to clean your rifle. Like mentioned check the torque on your action screws. That can make a huge difference.
Bruce

@gillettehunter
I'm thinking along the same lines as yourself. The can may be different causing the barrel to touch the stock when it heats up.
I had a Sabatti 223 that eould string shots vertically. Solution was to bed the action and float the barrel. Problem disappeared.
If it is grouping with the different can I would just use the can it likes and call it quits. as we know all rifles are a law unto themselves.
Bob