Reading this thread I was reminded that somewhere I had stashed a rim thickness (or relative rim thickness) kit that attached to a 6 inch caliper. Having just completed the testing I did with my rifle and 27 different flavors of ammo (see my post under "Single Shot Rifles" "It followed me home") I thought it might be fun to measure some of the ammo and see if I could correlate the rims and the results. First I measured the PMC Rifle Match to see if I could account for the misfires. I set the caliper to zero on one of these rounds. The measurements taken were -.0002 to +.0005. This was the most consistent variance of any of the ammo that I checked. In spite of that, it produced one of the 4 worst groups. Having established a baseline, I measured the ammo that had given the 4 best groups with the following results: Federal Auto Match .002 to .003; CCI Pistol Match .002 to .0035; Old Eley Tenex .0015 to .0025; and, Wolf Match Target .0005 to .002. Then I measured the ammo that had produced the 4 worst groups: the PMC noted above; Fiocchi Match .0005 to .003; Lapua Mstr L .0005 to .0015; and, Wolf Match Extra .001 to .003. Then I measured some ammo that had shot pretty good but had fliers: Remington SubSonic .001-.0025; Federal Gold Medal Match .002 to .0025. We see that the Fed GM is very consistent rim wise but yet fliers. Eley Match Black Label is generally considered to be good ammo so I measured it and got .001 to .002. Bottom line for me is that rim thickness and consistency doesn't seem to have a lot to do with how they perform in my rifle - it likes what it likes. Some perfect day I may put a scope on it and sort some ammo to .0005 and see if a difference shows up.

nsb shooting steel and shooting one hole small groups is like comparing Apples to Watermelons.

   I remember reading a piece (can't find the reference) where good results were had by sorting for run-out, and the best groups in given lots were with ammo that had the bullets noticeably loose in the crimp.  Presumably, this allowed the bullets to align themselves with the bore.
   That said, I have never done any sorting, and my experience is that "club" grade stuff works pretty fair at 100 yd, but you need the "good stuff" for 50 and 200 yd.  This apparent paradox is because the wind is not such a factor at 50 yd, and the lesser ammo tends to give noticeable vertical spread at 200.

CHRIS
RGChristensen

Seanmp wrote on Jun 3^rd, 2014 at 4:06pm:

What kind of groups are we talking about here? How many shots, at what distance, what group size? Maybe I don't know what the rim fire rifles are capable of. My Anschutz Exemplar (handgun) was capable of shooting five shots into .35" at 50yds and the shoot off chickens I shot at 100yds required sub 1moa to accomplish. I'm not sure if the results of the handgun vs. rifle aren't valid. The handgun wasn't a complete "poke and hope" effort. Even if the rifle shoots better (it probably does, I won't argue that point) the variables are equal in each type of firearm. Even the handgun is a game of skill and accuracy. The distribution of the group may be larger but the variables remain the same.

FRANK:
   Yes, "Nielson Brothers" was the article I read.  I recommend it to all who are interested in sorting .22rf.   Quite a nice piece with solid statistical background.   It was amazing that their .22rf testing discovered a fault in the 250# machine rest.

CHRIS
RGChristensen

nsb wrote on Jun 3^rd, 2014 at 7:11pm:

Great question! Right now, my 1871 receiver 38-55 #10 Ballard with a Shaver 22LR barrel insert is shooting ~1" groups @ 100-yard using CCI standard velocity - unsorted, whilst wearing a 10X Unertl scope. 

I have > 200 sorted so far by rim thickness and there is only a 0.003" range at the widest variation. And will try them at this week's competition.

From that article: "From this test we can formulate that for every .001" error in bullet run-out, dispersion increases 0.1 inch at 50 meters. "

More testing continues ...