In an attempt to find the ammunition that will work best for a particular application in my particular guns, I've decided to acquire as many makes and models of .22 rimfire ammunition as practical and test it. This will be a long-term project and I'll update this thread periodically as more data is acquired.
One portion of the testing is chronographing each make and model. The chrono procedure I use is the same as my procedure for developing my USPSA / IPSC loads. Barrel will be clean prior to each test. 30 rounds will be passed through the screens. Distance of the start screen will be 10 feet from the muzzle. All shooting will be done from a rest. Chronograph was a CED M2 mounted in a coffin with IR lighting. As of May 2020 the chrono is a LabRadar. Testing with known loads revealed that the data from the optical unit and the radar unit can be considered identical.
The subject of Standard Deviation often generates discussion. To make SD a useful and accurate measure of ammunition performance you have to test enough rounds to make the results statistically meaningful. The big mistake many people make is only testing 5 or 10 rounds and calling it good. It's not. Those who know way more than I do about statistical analysis say that 30 is a magic number. Any less and you don't have enough data to work with and any more you approach a point of diminishing return. To read more about statistical analysis in chrono testing, go to www.brianenos.com/forums and go to this thread. Now that you have a SD, what do you do with it? A SD of 5 or less in factory ammunition is probably a mistake. From 6 to 12 is outstanding. Truly the best of mass-produced ammunition. From 13 to 20 is very good. 21 to 30 starts to get to the average, nothing special range. 31 to 39 is not that great. Shoot it if you have to. 40 and over will be discarded outright. I wouldn't use it if you gave it to me. This seems to hold true with any ammunition, centerfire or rimfire, low to very high velocities. What a low SD on a particular lot of ammunition tells you is its consistency. Shot to shot, the velocity will vary little from the mean. To get good accuracy, one part of the equation is consistent ammunition.
Extreme Spread is to me a somewhat less useful measure of ammunition performance. For example, a test batch that goes an average of 700 FPS with an ES of 10 is not the same as another batch going 1400 FPS with an ES of 10. ES is nice to know but your SD will tell the tale. Let's throw this 'what if' at you. You have Brand A ammunition and Brand B ammunition, both are advertised as going 1000 FPS. Brand A goes across the chrono between 995 FPS and 1005 FPS fairly evenly spread out with a couple at 1005, another couple at 995, etc., with a third of the test batch going 1000 FPS. ES is 10 and the SD is 3.5. Good stuff huh? You try Brand B. 29 rounds goes exactly 1000 FPS. The last goes 990 FPS. ES is 10 and the SD is 1.8. Same ES as Brand A but Brand B has a lower SD. I'd use Brand B as being more consistent.
One thing I won't tell you is how accurate one ammunition is from another. As anyone who plays with rimfires know, each arm is a law onto itself. What works in mine may not work in yours. What works at 50 feet may not work at 50 yards. The only way you can find out is go to the range and punch holes in paper. This chrono testing is to separate the wheat from the chaff in my guns.
The guns used.
Ruger 10/22 with the following setup.
* Built in 2008 with a very rough guess of 5,000 rounds through it.
* Receiver from a Ruger 10/22RB. Modified by chamfering rear of bolt and headspacing. Work done by CPC Engineering.
* Bolt mating surfaces were polished.
* Volquartsen bolt buffer.
* Stamp marks from firing pin removed and mating surfaces polished.
* Trigger job performed by Clark Custom.
* Adams and Bennet 18" stainless bull barrel.
* Fajen thumbhole sporter stock.
* Mueller APV 4.5-14×40 AO scope on Weaver TO-9 base with Leupold rings.
CZ-452 American with the following setup.
* Stone stock with at least 5,000 rounds through it.
* Mueller APV 4.5-14×40 AO scope with Warne 7.3 rings.
* 22.5" barrel.
Ruger MKII with the following setup.
* Well used with approximately 20,000 rounds through it.
* 6 7/8" barrel and receiver stock.
* Volquartsen accuracy kit.
* Volquartsen extractor.
* OKO red dot optical sight.
* Either Volquartsen or Hogue grips depending on the game I'm playing at the time.
Taurus 94 with the following setup.
* Approximately 1500 rounds though it.
* Stock as it came from the factory.
One portion of the testing is chronographing each make and model. The chrono procedure I use is the same as my procedure for developing my USPSA / IPSC loads. Barrel will be clean prior to each test. 30 rounds will be passed through the screens. Distance of the start screen will be 10 feet from the muzzle. All shooting will be done from a rest. Chronograph was a CED M2 mounted in a coffin with IR lighting. As of May 2020 the chrono is a LabRadar. Testing with known loads revealed that the data from the optical unit and the radar unit can be considered identical.
The subject of Standard Deviation often generates discussion. To make SD a useful and accurate measure of ammunition performance you have to test enough rounds to make the results statistically meaningful. The big mistake many people make is only testing 5 or 10 rounds and calling it good. It's not. Those who know way more than I do about statistical analysis say that 30 is a magic number. Any less and you don't have enough data to work with and any more you approach a point of diminishing return. To read more about statistical analysis in chrono testing, go to www.brianenos.com/forums and go to this thread. Now that you have a SD, what do you do with it? A SD of 5 or less in factory ammunition is probably a mistake. From 6 to 12 is outstanding. Truly the best of mass-produced ammunition. From 13 to 20 is very good. 21 to 30 starts to get to the average, nothing special range. 31 to 39 is not that great. Shoot it if you have to. 40 and over will be discarded outright. I wouldn't use it if you gave it to me. This seems to hold true with any ammunition, centerfire or rimfire, low to very high velocities. What a low SD on a particular lot of ammunition tells you is its consistency. Shot to shot, the velocity will vary little from the mean. To get good accuracy, one part of the equation is consistent ammunition.
Extreme Spread is to me a somewhat less useful measure of ammunition performance. For example, a test batch that goes an average of 700 FPS with an ES of 10 is not the same as another batch going 1400 FPS with an ES of 10. ES is nice to know but your SD will tell the tale. Let's throw this 'what if' at you. You have Brand A ammunition and Brand B ammunition, both are advertised as going 1000 FPS. Brand A goes across the chrono between 995 FPS and 1005 FPS fairly evenly spread out with a couple at 1005, another couple at 995, etc., with a third of the test batch going 1000 FPS. ES is 10 and the SD is 3.5. Good stuff huh? You try Brand B. 29 rounds goes exactly 1000 FPS. The last goes 990 FPS. ES is 10 and the SD is 1.8. Same ES as Brand A but Brand B has a lower SD. I'd use Brand B as being more consistent.
One thing I won't tell you is how accurate one ammunition is from another. As anyone who plays with rimfires know, each arm is a law onto itself. What works in mine may not work in yours. What works at 50 feet may not work at 50 yards. The only way you can find out is go to the range and punch holes in paper. This chrono testing is to separate the wheat from the chaff in my guns.
The guns used.
Ruger 10/22 with the following setup.
* Built in 2008 with a very rough guess of 5,000 rounds through it.
* Receiver from a Ruger 10/22RB. Modified by chamfering rear of bolt and headspacing. Work done by CPC Engineering.
* Bolt mating surfaces were polished.
* Volquartsen bolt buffer.
* Stamp marks from firing pin removed and mating surfaces polished.
* Trigger job performed by Clark Custom.
* Adams and Bennet 18" stainless bull barrel.
* Fajen thumbhole sporter stock.
* Mueller APV 4.5-14×40 AO scope on Weaver TO-9 base with Leupold rings.
CZ-452 American with the following setup.
* Stone stock with at least 5,000 rounds through it.
* Mueller APV 4.5-14×40 AO scope with Warne 7.3 rings.
* 22.5" barrel.
Ruger MKII with the following setup.
* Well used with approximately 20,000 rounds through it.
* 6 7/8" barrel and receiver stock.
* Volquartsen accuracy kit.
* Volquartsen extractor.
* OKO red dot optical sight.
* Either Volquartsen or Hogue grips depending on the game I'm playing at the time.
Taurus 94 with the following setup.
* Approximately 1500 rounds though it.
* Stock as it came from the factory.
