I am going to start checking rim thickness of 22 rim fire ammo, segregate them and shoot them for accuracy.

So far I gave ceked hefollowig

1. Federal Champion Value pack. I took 50 rounds from the box and checked them.

Thickness is in thousands of an inch.

38 3
41 4
42 23
43 13
44 6
46 1

2. Winchester Wildcat

38 3
39 12
40 21
42 13
44 1

3. SK Standard Plus

40 3
41 28
42 19

4. CCI Blazer

41 12
42 35
43 3

5. Federal Gold Medal - old

40 11
41 8
43 14
44 17

6. RWS HV HP

39 9
40 33
41 6
42 2

Lots of variance. What is the cause? Old equipment or equipment ill formed?
Thanks for your quest for .22 accuracy.

There have been so many people claiming one thing or another would improve 22 rim fire accuracy.

Frankly, non of these seem to work.

Expensive match ammo shoots better, that is it.

I will shoot these, as well as others of better quality, and see.

My idea is to shoot groups with similar rim thickness together, and shoot groups of varying rim thickness.

We will see how they shoot.

The shooter is eliminated from this, as I am using a return to battery machine rest.

Well, sorting on rim thickness has always made more sense than sorting by cartridge weight (although there a number of rimfire shooters who still insist on sorting by cartridge weight, despite it making zero sense from the viewpoint of pure logic).

Nonetheless, in my own experience, sorting on rim thickness (with several devices), I've found absolutely no accuracy advantage in doing so--despite the fact that it at least would seem to make a little sense.

quote:

Originally posted by South Pender:
Well, sorting on rim thickness has always made more sense than sorting by cartridge weight (although there a number of rimfire shooters who still insist on sorting by cartridge weight, despite it making zero sense from the viewpoint of pure logic).

Nonetheless, in my own experience, sorting on rim thickness (with several devices), I've found absolutely no accuracy advantage in doing so--despite the fact that it at least would seem to make a little sense.

Maybe because there are more than one variable involved, we usually only sort on one of them and the variation in the others adds up.

A more extensive test with multi-variate regression might illuminate the matter. I'll guess that Eley and Lapua do this already.

quote:

Originally posted by TomP:

quote:

Originally posted by South Pender:
Well, sorting on rim thickness has always made more sense than sorting by cartridge weight (although there a number of rimfire shooters who still insist on sorting by cartridge weight, despite it making zero sense from the viewpoint of pure logic).

Nonetheless, in my own experience, sorting on rim thickness (with several devices), I've found absolutely no accuracy advantage in doing so--despite the fact that it at least would seem to make a little sense.

Maybe because there are more than one variable involved, we usually only sort on one of them and the variation in the others adds up.

A more extensive test with multi-variate regression might illuminate the matter. I'll guess that Eley and Lapua do this already.

Good point. The only problem is that the several variables with rimfire cartridges--bullet weight, cartridge case weight, powder charge, primer weight--aren't knowable to the shooter who has only the loaded round to evaluate. Eley and Lapua, on the other hand, do, of course, have the data on the individual variables and can study them in isolation.

That's why weighing rimfire cartridges makes no sense, although I gather a number of rimfire target and BR shooters do this. Two cartridges could have exactly the same weight, but varying bullet weights, case weights, charge weights, and primer weights--all variables that cancel each other out in arriving at the same cartridge weights. On the other hand, two cartridges could have widely different weights, but have identical charge weights with that variable being the key factor.

Excel will do linear regression, meaning that you must guess at the nonlinear functions and transform the data first.
You are right about observable variables, some of them can be measured or inferred and others no better than a guess based on other observables.
A large enough point cloud might yield some inductive conclusions about the difficult-to-observe.

Does the variance in thickness of the rim enable the primer amount to vary in quantity or in its thickness?

When all this is tested and sorted will any of us be better off behind our sights?

Not sure what it means.

I have shot them all and will post the targets once I have marked the.

The more I shoot 22 rim fire the more I am convinced there is no sure way of telling what is wrong!

quote:

When all this is tested and sorted will any of us be better off behind our sights?

The short answer is "maybe". Obviously you are not familiar with the BR 50 discipline, now pretty much defunct. BR stands for Bench Rest, so if by sights you mean open sights, then NO you won't be better off behind your sights. If by sights you mean your 20x scope, then it might make a difference. the question of rim thickness providing a measurable variable to demonstrate uniformity has been around for 30 years or so. I still have my rim thickness gauge. It shows differences in rim thickness not an exact number, but it does allow for grouping rounds of similar rim thickness, thus allowing for "uniformity". The claim was that non match ammo, if grouped by rim thickness, would shoot as well as match ammo. I was not able to confirm this with my Anschutz!
Peter

I tried sorting by rim thickness, no improvement in accuracy.

I think small chambers make a difference in .22 accuracy. I think that's because the round is lined up straight and has a harder time getting cocked in the chamber. I would have thought uniform rim thickness, or even just a very thick rim, would have the same affect. Kind of surprised it doesn't.

I would also guess a better way would be sorting for a long COAL on the round getting the round to start into the lands ideally. Long and fat would be even better. Essentially making the chamber tight by using only big .22 cartridges.