OAL/OGIVE WIDTH/Rim Thickness - Impact on Accuracy?

[fljp2002]

Fellows

This evening I pulled out my caliper and sampled one round from the different types of ammo I have on hand.

SAAMI Specs says .22LR should have an Overall lenght (OAL) of .985, The ogive should be .224 and Rim thickness should be .040.

Here is my sample data:

SK Std Plus - OAL .970, Ogive .224, Rim .041
SK Rifle Match - OAL .980, Ogive .222, Rim 0.42
SK Biathlon Sport - .983, Ogive .223, Rim 0.42
Eley Force - OAL .990, Ogive .224, rim .385
Lapua Polar Biathlon .987, Ogive .223, rim .040
Fed Bulk 36gr HP - .960, Ogive .221, Rim .042
Winchester Bulk 36gr HP - .971 Ogive .221 rim 0.33
CCI Sub Sonic HP - .964 Ogive .220, rim 0.039

As my data shows, not one of the round I sampled are exactly on spec. The bulk are shorter than spec, The ogive are under yet SAAMI spec idicates that for .22LR is better for the OGIVE to be a little biger to engage in the grooves better and finally rim thickness was closest in most type.

So my questions are these:

Of these three measurement, which should have the most impact on accuracy

If on cold winter night while enjoying a nice glass of wine or whiskey, one was to sort ammo which measurement would you prioritizes for sorting your ammo and is the process worth the squeeze.

 

[trevj]

Of those measurements, none of the above.
The only result that matters is at the target.
You have no control over how the ammo is made, so you test how it performs.

The joy of Standards. So many to choose from. And so wide a range of tolerances too!

 

[bearhunter]

The one thing you can change on rimfire cartridges is the rim thickness. Not the thickness of the metal of course.

I have seen and used clamps set up for equalizing the rim thickness on cartridges to get consistency .

Back in the day, many shooters felt that inconsistency of rim thickness played a big role in accuracy. I bought into that line of thought a few decades back.

These days there if very little difference between rim thickness, .030 plus or minus .001 is the norm. Not enough to worry about imho.

I measured four different lots of Aguila last week to try out in my new Tikka T1. All four batches measure .030

I also measured Remington sub sonic, Federal Gold Metal Match, Blazer and some very old Dominion Industries for comparison.

The recent manufacture ammo all measured within plus or minus .001 of .030. The Dominion ammo measured .028 to .035 in the same box.

A lot has changed with ammo reloading over the past 80 years. Make that over the past couple of decades. Some of the most consistently accurate 22 rimfire ammunition has been made over the last decade. One fellow I know tells me that quality has improved even more over the last five years and he's super anal about rimfire accuracy.

In his opinion a lot of off the shelf "standard velocity" ammo is now as good as most of the most expensive match ammo just over five years ago.

I don't really know. I pretty much got out of match shooting about a decade back, when my shoulders were telling me they needed the joints replaced. Same for trap shooting, which I miss the camaraderie as much as the shooting/competition. Sadly, I sold off my trap guns and a lot of the gear. I don't think at this stage of the game I will be getting back into it.

Sorry rambled off topic.

OP, your biggest issue with 22 ammo these days, will be finding which type your rifle shoots best. If you come across a lot/batch it likes, buy a case of 5000 or about as much as you will use in a year.

If you're only going to buy the odd 500 count brick or a box of 50 at a time, don't expect consistent tack driving accuracy.

It doesn't matter how well your rifle shoots for the most part. The reality of the matter is that for the most part, your rifle will change point of impact from point of aim with every different lot or every different manufacturer or different type/weight of bullet you shoot.

Whatever, learn how to adjust your scope well enough that you can bring your crosshairs and point of impact to be the same or at least close enough for the type of shooting you do with a few clicks on the turret rotors and of course, if your scope is so equipped by adjusting the parallax.

The results shown in the first post are interesting, but only point out the inconsistency of 22 rimfire ammo from one rifle to the next as well as from one manufacturer to another but only in one off lots.

 

[manitou210]

I like using the G3 ogive measuing tool, I check rim thickness, then measure with G3 tool and sort lengths, and test fire note target with ones that measured 27 & 28 lenghts seem to work the best target was at 50y

ATTACH]407141[/ATTACH]View attachment 407142

 

[bearhunter]

That's new to me, thanx for posting it and the great pics.

I've never noticed any difference in accuracy between ogives on 22rf bullets.

I do know one fellow that went to the extreme of building a device so that he could shave the cones off the tips of his bullets so they were all equal length.

Last time I spoke with him, he was still using it and working on a device to create precise hollow point cavities in the noses.

I'm waiting on the results of that one. The flat nose didn't make much difference.

Still, he's very bright and once he gets an idea in his head, won't let go of it until it's proven or disproven.

 

[horseman2]

Measuring Eley MATCH, TENEX, EDGE and TEAM for RIM thickness was almost an exercise in futility.
Sorting into two lots numbered 36 and 37 where any measurement of 37+ was "37" and anything less was "36".
The difference could be explained within the Same Shooter Different Day category.
ELEY is extremely consistent so it was only a matter of separating into two groups.
Had some TENEX that was split into the two lots and 36 shot just as bad as the 37.
Remington Eley MATCH with no measuring outperformed everything else at 192 Yards with the Cooper JSR.

 

[grauhanen]

This evening I pulled out my caliper and sampled one round from the different types of ammo I have on hand.

SAAMI Specs says .22LR should have an Overall lenght (OAL) of .985, The ogive should be .224 and Rim thickness should be .040.

Here is my sample data:

SK Std Plus - OAL .970, Ogive .224, Rim .041
SK Rifle Match - OAL .980, Ogive .222, Rim 0.42
SK Biathlon Sport - .983, Ogive .223, Rim 0.42
Eley Force - OAL .990, Ogive .224, rim .385
Lapua Polar Biathlon .987, Ogive .223, rim .040
Fed Bulk 36gr HP - .960, Ogive .221, Rim .042
Winchester Bulk 36gr HP - .971 Ogive .221 rim 0.33
CCI Sub Sonic HP - .964 Ogive .220, rim 0.039

As my data shows, not one of the round I sampled are exactly on spec.

Two things. Is a caliper the most appropriate measuring tool for reliable measurements for some of the categories? Also, unless a significant number of individual rounds of each variety were measured, it's not clear that the sizes would be statistically valid. (The Winchester bulk ammo package probably has a number of rounds with a rim thickness less than the 0.33 listed above.)
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If there's a consensus among serious .22LR shooters is that sorting by rim thickness is an unproductive use of time. They typically recommend and use top-tier match ammo, and that stuff doesn't vary significantly when it comes to rim thickness. Perhaps there are shooters who use bulk ammo may find some improvement when sorting by rim thickness, but when using bulk ammo the goal usually isn't noteworthy accuracy. Besides, the rounds that are sorted out in a process of elimination would nevertheless remain as inaccurate as ever, with only a part of a box being conceivably more accurate by virtue of culling by rim thickness. The more efficient alternative is to buy ammo that's a little better.

I have very recently been able to experiment with a G3 Base-to-Ogive length gauge, which a CGN member was generous to lend me. I sorted seven boxes of a certain lot of Midas + that was singularly unimpressive in consistent group size. The sorting took some time, and after I shot the sorted ammo and compared it to results obtained with unsorted Midas + of the very same lot, the results were quite similar. My provisional impression of sorting by base-to-ogive length is that it doesn't seem to affect results in a meaningful way.

By coincidence, I spoke to an ammo dealer the same day I shot the base-to-ogive ammo. The ammo dealer, who is also a very experienced shooter, said that his impression based on anecdotal information gleaned over the years, is that experienced shooters don't find sorting with gauges of any type has a significant impact on accuracy. He said that, instead of using sorting, the vast majority of competive shooters rely on lot testing good quality ammo to find the lots that will deliver the best accuracy in their rifles.

I don't think that there's any device or gauge (or trick for that matter) that will turn ammo that gives what's been described as "meh" groups into something that is very good. There are no shortcuts. I'll be lot testing when the next shipment of Lapua comes in.

the Same Shooter Different Day category.

If the "Same Shooter Different Day" category you refer to means different results produced by the same shooter and rifle and the same ammo -- I'd have to say that it's a thing. More than once I've shot the same ammo on different but equally calm days only to see very different results. How to explain it seems an entirely different matter, one which I don't really know where to begin.