Testing 22 LR Ammo

[SheepDog]

I, too, am a silhouette shooter and the change in group size at 75 and 100 yards I can attribute to transonic flight. When I use subsonic ammunition the groups stay together but switching to 1250 fps rounds (that chronograph at 1210 to 1240) the groups open up at 75 yards and just get bigger at 100. This aberration doesn't fit muzzle velocity changes and is nearly random in its pattern. I don't use the higher priced target ammo because while from a bench it makes a lot of difference when I shoot the match it is without any support - no sling, no resting an arm on ones hip, no shooting vest - and my accuracy is more or less the larger component of any group size beyond 50 yards. As I get better I may try using the more expensive ammo but for now I have to work on my upper body strength (and back) before it will be worth doing.

 

[moorepower]

I test sample lots of 22LR at an indoor range at 100 yards. I have never found it to not shoot very well at 50 if it shoots well at 100.

I agree with this, but if you are shooting at 50yds., the most accurate at 50yds. will not always be the most accurate at 100 yds.

 

[patriot]

the most accurate at 50yds. will not always be the most accurate at 100 yds.

Which proves compensation is occurring; wouldn't be the case if the node theory were correct.

 

[Clark]

A lot depends on the velocity of the bullet. A high velocity 40 grain bullet transitions from super sonic to subsonic on the way out to 100 yards. That is why it is not unusual for high velocity bullets to lose the ability to hold a group beyond 50 to 75 yards. If you are starting with subsonic ammo then testing is best done at 100 yards.

This is consistent with my testing.

 

[rkittine]

Wednesday my first RF Bench Rest Rifle is arriving. I have multiple lots of many different match rounds. Lapua Midas+ and Center X, Eley Tenex and Match, etc.

I want to shoot it at 50 yards, but also 200 yards at Williamsport. Since I have access to a 100 yard indoor range, that is where I am going to start testing and go from there.

This my first forey into rim fire bench rest and I have bought the tools to check rim thickness, overall length, bear surface etc., so I will have pre-sorted including by weight, even though I have gotten more input that sorting doesn't work than that it does.

Bob

 

[Tim s]

Given your stated ammo, take your tools to measure and throw them all away. Nobody measures or weighs this stuff....nobody.
What you are likely to do is take that nice lube on ELEY, and screw it up.

 

[patriot]

My limited testing agrees with what Tim said on weighing ammo. The Lapua CenterX, Midas, and X-Act ammo weight variance is so small why bother. Running Eley heavy's vs lights through the chronograph; no measurable difference in ES or SD. I recently purchased a rim thickness gauge that won't mess up the wax; had the same concern. Heck, I don't even transfer the ammo to a loading block over concern for the wax. Spot checking five different brands of ammo, the good stuff didn't show much rim thickness variance. When I get time I'll run the ES/SD test across the price range to see if there is any measurable correlation.

On a side note, I have some decent Eley Team where the wax is hardening. It will provide an interesting test.

Mark

 

[seymour fish]

My limited testing agrees with what Tim said on weighing ammo. The Lapua CenterX, Midas, and X-Act ammo weight variance is so small why bother. Running Eley heavy's vs lights through the chronograph; no measurable difference in ES or SD. I recently purchased a rim thickness gauge that won't mess up the wax; had the same concern. Heck, I don't even transfer the ammo to a loading block over concern for the wax. Spot checking five different brands of ammo, the good stuff didn't show much rim thickness variance. When I get time I'll run the ES/SD test across the price range to see if there is any measurable correlation.

On a side note, I have some decent Eley Team where the wax is hardening. It will provide an interesting test.

Mark

With the sun behind you, low in the sky, fire 1 round at 100. If it flies in a corkscrew, stop right there, as it won't group

 

[Outrider27]

.... I recently purchased a rim thickness ..... Spot checking five different brands of ammo, the good stuff didn't show much rim thickness variance.

Mark

My testing has shown that rim thickness testing can make a noticeable difference in group size WITH BULK AMMO, where there is always a significant range of rim thickness, and the thicker the rim, up to about 0.040", the more accurate it is (from 0.040" to 0.043" group size doesn't seem to improve noticeably). My testing of rim thickness on high quality ammo yields the same results as have been stated above for weight sorting; high quality ammo has a much smaller rim thickness range, and that range is at the upper end of the thickness range normally found when measuring bulk ammo. Since rims in the 0.040 and up range and consistent (small range from smallest to largest) yield the best accuracy, rim thickness measurement of high quality ammo, like weight sorting of same, isn't worth the effort.

With bulk ammo, we threw anything less than 0.035" in the barrel fowler pile and grouped the rest in 0.001" groups (to the nearest thou) from 0.035" to 0.040 for testing - anything over 0.040" went into the "we got lucky box" - in measuring a 320 to 500 round bulk pack, there would be very few in the "we got lucky box"- sometimes enough for a 10 shot group test. They always grouped noticeably better than, say, a bunch from the 0.036" pile, but rounds sorted by thickness from a bulk pack group better than groups fired with randomly selected rounds out of the same size bulk pack.

Mike

 

[seymour fish]

My testing has shown that rim thickness testing can make a noticeable difference in group size WITH BULK AMMO, where there is always a significant range of rim thickness, and the thicker the rim, up to about 0.040", the more accurate it is (from 0.040" to 0.043" group size doesn't seem to improve noticeably). My testing of rim thickness on high quality ammo yields the same results as have been stated above for weight sorting; high quality ammo has a much smaller rim thickness range, and that range is at the upper end of the thickness range normally found when measuring bulk ammo. Since rims in the 0.040 and up range and consistent (small range from smallest to largest) yield the best accuracy, rim thickness measurement of high quality ammo, like weight sorting of same, isn't worth the effort.

With bulk ammo, we threw anything less than 0.035" in the barrel fowler pile and grouped the rest in 0.001" groups (to the nearest thou) from 0.035" to 0.040 for testing - anything over 0.040" went into the "we got lucky box" - in measuring a 320 to 500 round bulk pack, there would be very few in the "we got lucky box"- sometimes enough for a 10 shot group test. They always grouped noticeably better than, say, a bunch from the 0.036" pile, but rounds sorted by thickness from a bulk pack group better than groups fired with randomly selected rounds out of the same size bulk pack.

Mike

Mike, you are on to something here. My approach is to test cheap junk ammo at 50, looking for 2 or 3 separate groups. If so, rim thickness sorting I s likely to show 2 or 3 corresponding piles, each of which may show decent groups, in this individual rifle.

 

[seymour fish]

Mike, you are on to something here. My approach is to test cheap junk ammo at 50, looking for 2 or 3 separate groups. If so, rim thickness sorting I s likely to show 2 or 3 corresponding piles, each of which may show decent groups, in this individual rifle.

HeadSpace comes into it. Ex: factory 10-22 sloppy .055, proper 10-22 set to .043, target bolt actions with adjustable HeadSpace for a reason

 

[Outrider27]

I originally got the idea to test quantities of ammo sorted by rim thickness from some discussion in a book I purchased years ago titled (if memory serves) "Customizing the Ruger 10/22", where they mentioned improved accuracy from rim thickness testing. To limit the other variables, such as head space, as much as possible, I did all the testing with the same rifle, a bull barreled Marlin target rifle that had always performed more than adequately for me. Once I advanced into the higher quality brands sold as match ammo as opposed to bulk pack ammo, I quickly determined that rim thickness was much more consistent, with a MUCH smaller range from thinnest to thickest, and skewed well toward or at the high end of what I was used to seeing previously in my sorting of bulk pack ammo. After shooting a few 5 shot groups with various of the the higher end stuff, I quit measuring them and just included them, straight out of the box, when testing any .22 to see what ammo(s) it preferred.

I have no way to scientifically explain why the sorted bulk ammo shoots better groups than unsorted bulk ammo, or why groupings at the thick end of the rim thickness range shoot better than those at the thin end, but I do have a best guess, based on discussion with center fire short range (100 and 200 yards) bench rest shooters, specifically my late cousin in law and the late Homer Culver, both bench rest Hall of Fame shooters. I had asked then about charge weight accuracy when throwing charges from a powder measure (I had noticed that short range bench rest shooters just threw the charge out of their measure into the case, no weighing and "trickling up"), and both said not to worry about it at 100/200 yards, just develop a rhythm for operating the powder measure that gave the most consistent charges I could throw and let it go at that, because at those ranges primer performance is more important than +/- a tenth of a grain or less of powder. After watching them and others test the same load with various different primers, I had to agree - even with weighed charges, primer choice could make or break a load with the level of precision they were looking for, and primer ignition consistency was king. So my best guess is that rim thickness effects ignition consistency, so that the best accuracy a batch of cartridges is capable of comes from grouping them by rim thickness when it varies a lot, as in bulk pack ammo, to improve ignition consistency, and that a thicker rim further improves ignition by maximizing ignition consistency still further - ammo that is all in the 0.040"-0.043" always shot great, you just got a whole lot more of it (often a complete box of 50) with high end ammo than with bulk pack ammo, where sometimes you didn't get enough to fire 2 five shot groups out of a 500 round brick. Anyhow, that's my best guess - sorting improves ignition consistency up to a point, and from 0.040"/0.041" on up, you've reached the optimum rim thickness with regard to ignition consistency.

Whether my best guess with regard to ignition consistency is right or wrong, it was a fun ride doing all that testing.