Is it necessary to let a factory tikka barrel cool when trying to find the most accurate ammo for it?

[Elite]

I have read some posts on here regarding how a hot barrel doesn’t seem to affect a tikka barrel,

This is my first tikka and all my other rifles in the past have suffered the hot barrel issue. So I don’t want to waste ammo if all tikkas don’t shoot well when the barrel is warm


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[HighUintas]

https://rokslide.com/forums/threads/cold-bore-zero-versus-very-hot-bore-zero-test.325335/

 

[Macintosh]

I havent done a scientific comparison myself, but I do not let my tikka barrels cool. As I go from 2 round to 3-5 rounds to 6-8, to 9-10 in a group, the center of group does not seem to move in a predictable manner, certainly not in a linear manner, so I do not believe mine are heat sensitive, at least not enough that I'd be able to tell. Only one way to tell for certain though.

I think 99% of people shoot 3 round groups, which are going to show differences from group to group simply due to the dispersion of the rifle. My strong suspicion is that most of people's issues with "must be the barrel heating up" is the luck of the draw on the 3-round groups they shoot. Using a 10-round or larger group as the comparison would eliminate most of this sort of error.

 

[5811]

https://rokslide.com/forums/threads/cold-bore-zero-versus-very-hot-bore-zero-test.325335/

Important distinction to make is that experiment was to test a shift in zero from cold to hot, not group size.

My subjective observation is that most rifles used for that test appeared to open up a bit when hot, so while it might show that a cold-to-hot zero shift was not observed, it definitely provides no data to show the dispersion of impacts does not change from cold to hot, which is what the OP was asking about.

 

[45-70guy]

Personally to me it matters on barrel profile how long I’ll go between shots if I’m load developing, weather or not it matters I just keep my system consistent on my process.
I’ll do a time limit on my groups between each increasing load just to be somewhat consistent on barrel temp.
I find it matters more on my pencil sporter barrels than my thicker straight or Bull barrels.

 

[Formidilosus]

Important distinction to make is that experiment was to test a shift in zero from cold to hot, not group size.

My subjective observation is that most rifles used for that test appeared to open up a bit when hot, so while it might show that a cold-to-hot zero shift was not observed, it definitely provides no data to show the dispersion of impacts does not change from cold to hot, which is what the OP was asking about.

That is due to barrel mirage, not barrel heat causing a mechanical opening of the groups.

 

[david2duck]

Hot barrel doesn’t matter. This is a 30 round group. Gun only rested long enough to reload the mag. We even passed the rifle off between my dad and I every 5 rounds.


Another 20 round group I shot by myself without letting the rifle rest.

 

[BKM]

Mine punches out 10 round 1” groups without issue. I’ve never tried more than that without a fair amount of time to cool down

 

[JGRaider]

I havent done a scientific comparison myself, but I do not let my tikka barrels cool. As I go from 2 round to 3-5 rounds to 6-8, to 9-10 in a group, the center of group does not seem to move in a predictable manner, certainly not in a linear manner, so I do not believe mine are heat sensitive, at least not enough that I'd be able to tell. Only one way to tell for certain though.

I think 99% of people shoot 3 round groups, which are going to show differences from group to group simply due to the dispersion of the rifle. My strong suspicion is that most of people's issues with "must be the barrel heating up" is the luck of the draw on the 3-round groups they shoot. Using a 10-round or larger group as the comparison would eliminate most of this sort of error.

As those 10 shot groups open up, which they all do to some extent, how much error is attributed to shooter error, environmentals, mirage, etc?

 

[Macintosh]

As those 10 shot groups open up, which they all do to some extent, how much error is attributed to shooter error, environmentals, mirage, etc?

none or all of it depending on how you look at it.

If I shoot 1-shot groups or 3-shot groups, and overlay all of my groups, the group-size ends up the same as if I shoot one big group. Of course if I get up and build a new position for every group that adds to it...but for instance if I shoot 30 1-shot targets like a rimfire benchrest target without getting up, and overlay all of those shots onto one target, the group doesnt end up measurably different than if I sit down and fire the same # of shots in one go at the same target.

I am just as likely to pull a shot shooting small groups as I am shooting large groups. So if you want to have a realistic representation of what the whole system--the gun/scope/connectors/shooter--is capable of, then it's irrelevant, because it's built in to each way of shooting groups equally. So unless it's a stupidly obvious called miss (would have to be on the order of an ND, shot the wrong target, etc for me to ignore it) I count them all--with a heavy gun it's pretty easy to manage this, but even so I can call misses reasonably well and I dont have the feeling that the shots making up the fringe of my larger groups were bad trigger presses or shooter error. So not much scientific to report here, more my gut feeling from playing around with this a bunch.

Mirage--I think this matters more, at least that's my impression. I notice it more in cool weather when there isnt any breeze. Generally a breeze helps with this. It's not usually an issue shooting a 10-round group, but if I shoot multiple 10-round groups fairly quickly I definitely notice it. That's actually my measure of when I let things cool, ie I can visibly see the mirage. Where i live we dont have mirage very often as a natural condition like many of you folks who live in more arid areas do, so it's pretty easy to say for certain when mirage is from the barrel versus what isnt. But under decent conditions with a little breeze the barrel can still be too hot to touch without seeing a measurable degradation of my groups.

Bottom line, I have let it cool, I have eliminated anything that felt like a pulled shot, and it doesnt seem to matter. So i no longer let it cool, I no longer ignore shots unless there is a 100% positive problem with shooter or gun. I do let cool, but only to deal with obvious mirage from barrel, which most of the time still allows for multiple 10-round groups before a rest. I usually pull out the 22 or a pistol and shoot that for a bit while rifle cools.