That's centerfire primers only. Rimfire is automated; a drop of liquid primer is placed into a spinning case.
Sort Ammo by Rim Thickness, Reduce Flyers
- Thread starter Zee705
- Start date
That's centerfire primers only. Rimfire is automated; a drop of liquid primer is placed into a spinning case.
Thanks.
What's shown in that part of the video is only one part of the entire, more complex case priming process. It appears to show the step in which a pellet of primer is introduced into the casing, which is sort of half-way through the complete priming procedure. The primer pellet still needs to spun centrifugally into the rim of the casing. Then the primed cases need to be dried appropriately. Quality control steps are taken through the process.
Keep in mind that CCI reportedly makes about 4 million .22LR rounds every day. Even the manufacture of match .22LR ammo uses machinery in every step of production.
For more details, see George Frost's book Ammunition Making, pages 66 - 68 for the priming process for non-match .22LR rimfire ammo. The priming process as well as other details for match ammo production is described in Chapter 12 of the Frost book. This book is an excellent source of information on the manufacture and production of rimfire and centerfire ammunition.
Does this book talk about rim thickness at all?
In the chapter on .22LR match ammunition, on page 135, Frost says the following:
Head diameter gauging, which should be 100%, is set to closer limits [for match ammunition] than for standard [non-match] ammunition. The normal specification is .269 - .276". For match, .2710 - .2740" is a good range, although it might have to be adjusted up or down a little for best sensitivity. Any cases gauged out [of match specifications] here can still be used in regular production. Head thickness should be held to .039" - .042" as a rule. (Words in square brackets added for clarification.)
The last sentence is the relevant one regarding rim thickness for .22LR match ammo -- .039" - .042". I couldn't find similar figures for non-match .22LR ammo (of course that doesn't mean they're not there), but there is this diagram below from p. 13 of the Frost book, with a range of sizes given for rim thickness.
If you're interested in the book, there's a physical version of the book available on Amazon.com (US) for $320, which is prohibitively expensive. More practically, there is a pdf available that's gratis. Let me know if need help locating it.
As for whether sorting rimfire ammunition by rim thickness is worthwhile, there's nothing new to be found. The idea is old, tried, and generally not practiced by experienced shooters because it is found to be time poorly spent. It's most frequent enthusiasts are among newer .22LR shooters who wish to get better accuracy out of inexpensive ammo. Inexpensive ammo is by it's very nature inaccurate ammo. The easiest, most straightforward way to improve accuracy, is to use better quality match ammo. Match ammo is made to more exact specifications. While not every match ammo performs equally well in a particular barrel, it offers the best odds of improved results.
When using match ammo and the results are unsatisfactory, it usually means one of two things. Either the ammo itself is not good, or quite often the barrel and chamber are not up to the expectations. Consistent and excellent results with even good ammo are not common with many mass-produced sporter rifles. They may be achieved on occasion, but they are generally not consistent.
Thanks thats great info. I quickly sorted a few boxes of different brands to see what the spread was within each brand/variety. It would be interesting to see what the rounds outside of the .039" -.042" range do compared to the ones within. Perhaps that will be something I test.
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Not so much the rim thickness, but the rim-to-ogive distance, where the driving band of the bullet starts. There is a tool that measures this. Each brand of bullet (as well as lots within a brand) will have a different measurement and this varies more than rim thickness. I saw a greater tolerance and consistency in Center-X for example, than the SK Flatnose. Can't say I could tell a difference on target for having sorted or not.
...I shoot Center-X as my go-toSo I’ve sorted and shot some rounds past the labradar. Haven’t shot any groups yet but I thought this would be a start as to understanding if sorting by rim thickness has an impact on how the ammunition performs.
Now before I post what I found I feel there are a couple important points to bring up.
1. .22LR rifles are very picky with ammunition, even if we had consecutive serial numbered rifles they may prefer or shoot better with different brands of ammunition.
2. This is by no means conclusive, as ultimately I would want to test group sizes at 100 and 200 yards where differences in ES would be easier to see.
3. I’m not a scientist, scholar or professional and am not claiming to be.
Here we go:
I started by purchasing a brick of CCI STD velocity target and a brick of SK STD +. I set aside 150 rounds from each brick to be left untouched. I took the remaining 350 rounds of each brick and started sorting by rim thickness. I found there to be a spread with each brand from 0.0395 to 0.0440. I sorted until I had 50 rounds of 0.041 of each brand.
For testing I used my DAR22 with 16.1” barrel and a labradar.
Shot 50 rounds of the untouched ammunition past the labradar, then shot 50 rounds of the sorted ammunition.
Here is the info collected:
CCI STD
Unsorted
High= 1132fps
Low= 1065fps
ES: 67
SD: 12.2
Sorted 0.041
High= 1121fps
Low= 1072fps
ES: 49
SD: 12.2
SK STD +
Unsorted 1
High= 1070fps
Low= 1004fps
ES: 67
SD: 14.5
Sorted 0.041
High= 1082fps
Low= 1022fps
ES: 60
SD: 11.5
Unsorted 2
High= 1080fps
Low= 1019fps
ES: 61
SD: 13.9
Sorted 0.043
High= 1070fps
Low= 1024fps
ES: 46
SD: 12.2
Now before I post what I found I feel there are a couple important points to bring up.
1. .22LR rifles are very picky with ammunition, even if we had consecutive serial numbered rifles they may prefer or shoot better with different brands of ammunition.
2. This is by no means conclusive, as ultimately I would want to test group sizes at 100 and 200 yards where differences in ES would be easier to see.
3. I’m not a scientist, scholar or professional and am not claiming to be.
Here we go:
I started by purchasing a brick of CCI STD velocity target and a brick of SK STD +. I set aside 150 rounds from each brick to be left untouched. I took the remaining 350 rounds of each brick and started sorting by rim thickness. I found there to be a spread with each brand from 0.0395 to 0.0440. I sorted until I had 50 rounds of 0.041 of each brand.
For testing I used my DAR22 with 16.1” barrel and a labradar.
Shot 50 rounds of the untouched ammunition past the labradar, then shot 50 rounds of the sorted ammunition.
Here is the info collected:
CCI STD
Unsorted
High= 1132fps
Low= 1065fps
ES: 67
SD: 12.2
Sorted 0.041
High= 1121fps
Low= 1072fps
ES: 49
SD: 12.2
SK STD +
Unsorted 1
High= 1070fps
Low= 1004fps
ES: 67
SD: 14.5
Sorted 0.041
High= 1082fps
Low= 1022fps
ES: 60
SD: 11.5
Unsorted 2
High= 1080fps
Low= 1019fps
ES: 61
SD: 13.9
Sorted 0.043
High= 1070fps
Low= 1024fps
ES: 46
SD: 12.2
how high
Taking that as a question, you can look at the information collected and included above in post #34 or see it reproduced below.
As noted, sorted or unsorted, the ES and SD are high.
I know, I’m the one who posted the info. I’m asking how high are they. IE what should they be?
At the risk of making it sound like a tautology, the results are what they are because the relatively inexpensive ammo is not going to give especially good numbers. If they were compared to bulk .22LR ammo, the numbers might look good in comparison, but they are not unusual for CCI SV and SK +.
