Impact of bayonet-style chronograph on group size

[J-B welder]

I have read repeatedly that bayonet chronos will affect POI. Will they affect group size or shape as well?

 

[GW Hunter]

I would say yes. Anything attached to the barrel would have to affect the harmonics. Shoot a couple groups with and shoot a couple without and compare…

 

[Rick Richard]

I have read repeatedly that bayonet chronos will affect POI. Will they affect group size or shape as well?

On all my rifles it did.

 

[J-B welder]

Thanks, good to know.

 

[twister]

yes it definitely changes your groups.

 

[ntg]

Generally mine does, some quite a bit. The exception is mod 10FP, 308. It has a 20", bull barrel. It doesn't seem to open up the groups, but they do move to the right about 1/2 an inch with that gun.

 

[Pdvdh]

Buy a LabRadar

 

[ShtrRdy]

Group size can get bigger OR smaller OR same when attaching a Mag-speed to the barrel.

 

[J-B welder]

Buy a LabRadar

That was fairly predictable.

 

[QuietTexan]

It's weight on the barrel, it will change the harmonics. Suppressors do they same thing, and a barrel tuner is based on this principle. There's no way I know of other than shooting to determine the actual impact of the changes. If I'm shooting suppressed, I develop the loads with the suppressor on because groupings do change, not just POI, especially with the heavier cans.

 

[GLTaylor]

I agree with above. Only heavier contoured barrels show less influence, but POI moves on all of mine. Groups vary a bunch in lesser wt barrels.

 

[Pdvdh]

That was fairly predictable.

Best response so far = Spend Money.

 

[Pdyson]

I see an impact shift of about an inch or so at 100 but that doesn't bother me too much when doing load development. I'm only looking for a speed node and don't care where or how it groups. But if you do want to shoot groups while checking velocity or if you are shooting a suppressor. Wiser Precision has a carbon fiber rod that allows you to get off the barrel and adapts to a picatinny or arca-swiss rail. Costs about $100, light weight and tool-less. Check it out. https://www.wiserprecision.com/products/chrono-mount

 

[Another Casual]

Barrel contour will have an impact here as well. On my target rifle it shoots 1 moa lower but groups are largely the same. On my #2 contour hunting rifle it has more of an impact.

My main concern is just changes from the bayonet shifting I'm the middle of a group. I got a magnetosphere Sporter and live with it's limitations, the lab radar was beyond what I was willing to spend.