Lost interest but mine is broke in after I kill the first deer, pig, elk, yote, nilagi, or axis.

If memory serves, they were mass produced rifles. Same make, model, all features the same, different serial numbers. Since you're wanting to split hairs, it is physically impossible to have identical rifles. What was the ambient temperature outside when each barrel was forged? Did both barrels come from the same bar stock, produced in the same foundry? Was the moon phase the same when each barrel was drilled, rifled, and chambered?

Geez.

The gunsmith I use was almost offended when I ask him about break-in. He said “Boots hand lapped it when he made it and I hand lapped it after cutting the chamber. Load it and shoot it”. Which I did. Tried 5 different loads for a total of 25 shots, picked the best one which shot .2-.3 from that day forward.

I did have a new factory Tikka that started crappy but after 30 rounds or so settled into a solid .7 gun. I did not do any break in procedure for it and it cleaned up on it’s own.

I will refrain comments on Tony Boyers and Bryan Litz comments. I think most here "get it"

So there are two components of variation in studies like this. It’s referred to is within and between

Within variation would be within the group and would encompass everything you mentioned plus more. Assuming you have a process that outputs a barrel there will always be within variation. The reason you want a larger sample size is that you are trying to determine the limits of the within variation. Within variation can seen in all manaufcturing process. When a barrel manufactur puts a guarantee they are specifying the within variation

Between variation is the variation between two distinct groups. You can use many different variables to be the between variation. Again some of the factors you mentioned could be between factors. It all depends at what level you want to elevaute your process.

In this example it could be barrel break in for the between variation. If their is enough data points to show the between variation is statistically different than their is a difference.


As I said earlier there is no concrete evidence that it makes a difference. Their is a lot of ad how data to suggest it doesn’t make a meaningful difference. My personal conjure is that tuning ammo has more of impact than barrel break in on improving accuracy but atlas I do not have data to show this.

I thought I was being easy on everyone by not mentioning Heat Lots etc.

Please explain to me why asking what "Identical" meant in this situation is "splitting hairs"?

I think it was a valid question since "Identical" was being used to validate an end result.

Identical is subjective, to parameters set.

Red Snake and his friend Jake have matching custom made 280 A.I. rifles. Same barrel maker, same length, contour, twist rate, chambered by the same gunsmith, on the same lathe, with the same reamer. A load was developed on Red's rifle, that is a legitimate 1/4 MOA load, at various distances. The headspace of the two chambers is .001" different. Are they identical? Technically yes, and no. It depends on the standard. If the standard is .01", then they are. If the standard is .001", then they are not.

However, that same hand load, headspaced to -.001" ,to the shorter of the two chambers produces identical results in each rifle. They've been out past one thousand yards, I believe, both running the same elevation corrections at every distance. Does that make them identical? By some measures, yes.

If memory serves, the two .308's that were first mentioned produced the same results. Consistency in shooting, DOPE matching, on the same factory ammo. I really dont care about the heat, the bar the barrels were made from. I do care about what they do, once the trigger is squeezed, and they did the same things.

Barrel break in is a total waste of time.