Theoretical accuracy potential of 22lr ?

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RobSmith

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Just curious to see if anyone ever came up with a theoretical chart of the accuracy potential of the 22lr round ? Regardless of the gun in which it's fired, twist rate, weight, speed, bullet shape, barrel lenght etc... Is there such a thing as a minimum "standard" (Milspec, ANSI, whatever) of accuracy to be expected from 22lr ammo ? How would one go about crunching the numbers that would equate to the most accurate "potential" ammo for any given gun ?

I've seen people take potshots at targets as far as 200 yards with .22's (there was even a contest on that earlier this year on this board), but there sure seemed to be quite a spead on the impacts, more than one would expect from the shooter's skill level only (so there comes a point where the ammo itself starts spreading). What is the accepted norm where 22lr ammo is deemed "most accurate" range wise ?

Inquiring minds want to know ....
 
What is the accepted norm where 22lr ammo is deemed "most accurate" range wise ?
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Point blank. Actually that was a joke. Good question though. I would be happy with something that shot 2 inch groups at 100 meters. Smaller groups would be even better.
 
KDX said:
What is the accepted norm where 22lr ammo is deemed "most accurate" range wise ?
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Point blank. Actually that was a joke. Good question though. I would be happy with something that shot 2 inch groups at 100 meters. Smaller groups would be even better.
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Me too, however the way I'm trying to tackle the problem is to find out what range best suits the round, as opposed to what round best suits the range (we all know there are rounds out there with vastly superior average accuracy at 100M).
 
Hypothetically, the theoretical accuracy of any round would be N x bullet-diameter @ range X; where X is any any range. ie. 10 shots into a .224 hole (in the case of .22 rounds) at any range. Or put another way, its impossible to have a groupsize that is smaller than the bullet diameter. Any round could have this potential, regardless of calibre.

Once you factor in different tollerances in barrels, casings, bullet and powder composition, wind, humidity, air density and bullet speed, it gets a little more interesting. Factor in gun makers tolerances and shooters skills and you've got yourself a horse race.

Realistically, accuracy is often described as 5 (or more) shots into a 1" diameter circle at 100 yards. This is considered 1 minute of angle or 1 MOA (actually, its 1.05, but lets not quibble). 5 shots into 2" at 200 yards, 3" at 300 yards etc.

Any gun using any ammo that groups sub MOA at any range is considered "accurate" for most intents and purposes.

On the other hand, the most accurate load is probably achieved with one-shot groups. :wink:
 
One-shot group, i like that :lol:. I guess what I'm after is a sort of ratio of range vs accuracy of the ammo. For example take a .22 that would consistently shoot sub 1 inch groups at 25 meters, 1 inch groups at 50 meters (my TOZ-78, for example, does that fairly well), but then the group size would go up to say, 3 inches at 100 meters, take way shooter's skill by putting th gun in a vise, purely for the sake of argument. From a purely arithmetic standpoint, there is a point that is between 50 and 100 meters where the round itself starts to lose accuracy, that's what i'd like to find out about, and also, how can one calculate what the best theoretical range vs accuracy ratio (maximum effective range I guess) for any given round in a "perfect" rifle, and then derive from that what ammo one should feed one's gun ("perfect" combination of muzzle velocity, bullet eight, and bullet shape (aerodynamic coefficient I guess).

The questions come from experimentation that I did with my .22's, certainly not "match" rifles by any stretch of the imagination, I found that the most "accurate" ammo up to 50 meters <appears> to be the subsonic stuff, but I can barely keep my rounds on paper at 100 meters, yet if I switch over to the hyper-velocity stuff of approximately the same weight and shape (hollow point, plain lead), my 100 meter group does not significantly shrink, so obviously, there's something else than pure speed, weight, and shape going on there, I guess it may have something to do with the twist rate of the barrel.
 
Different guns like different ammo. Maybe you just haven't found the right stuff yet.
 
In theory, accuracy is a straight mathematical progression.
1/2 inch at 50 yards, 1 inch at 100 yards, 2 inches at 200 yards.
Bullets do loose stability but mostly it is outside factors acting on the bullet that causes it to become less accurate.
As the distance increases, wind has more time to act on the bullet.
A .22 bullet takes .068 seconds to get to a 25 yard target, .140 to 50 yards, .292 to 100 yards and .63 to 200 yards.
Drop at 200 yards is about 73 inches.

The same 10 mph wind that moves your bullet .25 inch at 25 yards moves it 4 inches at 100 yards.
 
Just a few random thoughts on what's been posted so far, and a few of my own.

The hole in the target is a bit less than .224" in dia- after travelling the bore, the bullet is somewhat "re-sized"- should be about .221" or so after firing- depending on how used the manufacturer's rifling button is. That hole in the target could be bigger too- depending on what's used for a backing board.

The theoretical progression of groups at differnent ranges is not a straight line mathematical progression- inversion occurs at about 300 yds, at least with the center-fires, and things really start opening up. I beleive through shooting experience, that inversion starts for the .22 lr just past 200 yds.
Winchester was getting 3/4" groups at 200 with the 52 target rifle in the late 40's- with the gun in a vise, shooting through an enclosed tunnel.

As for accuracy, the heeled (rebated) bullet of the lr makes it a poor choice for accuracy of any kind. That it shoots as well as it does is testament to both ammo and gun manufacturers' close attention to tolerances. It is my beleif that it doesn't take much to screw up lr ammo- Remington ammo is the best proof of this theory that I've seen in a while. I also think that the new .17 rimfires owe much of their accuracy to their flat based (non-rebated) bullets....

Regards,

Doc Sharptail
 
precision shooting magazine had a series of articles about this in the late 90s iirc about the same time there was talk of cancelling rimfire BR-50 as a class because the inherent inaccuracy of the 22LR round
the list of things that make teh 22LR inaccurate was 10-15 items long if memory serves
-case weight
-rim thickness
-lead bullet deformation entering chamber
-there is a little lead "ring" that forms in the camber where the bullet joins case upon firing some lead is "melted" more rounds=thicker ring, the ring did not come out with regular cleaning and of course one of the PS wizards came up with a chamber re-reamer to remove the lead
-inconsistent priming
-inconsistent powder weight

thats 6 from memory
 
My father was a ballistician for C.I.L. and their Shooting Sports development manager.
I asked him about rim thickness and headspacing when I was heavy in BR50 and he said that the majority of firearms manufacturers and Olympic shooters consider the crimp of the bullet the most important thing, as it is the hardest to control.
Periodic bullet pull tests are done when manufacturing rimfire ammo to test the crimp consistancy, but you have to desroy the bullet to do this.
Primers, rim thickness, OAL, lube, etc. can all be controlled and tested without actually firering the ammo.

Cat
 
catnthehatt said:
but you have to desroy the bullet to do this.

Cat
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That's a good way of doing things , Kind of like testing bombs. KABOOM!! hurray That one would have worked in battle ........

or in our case BANG !!! That would have been a good shot
 
Doc Sharptail said:
The theoretical progression of groups at differnent ranges is not a straight line mathematical progression- inversion occurs at about 300 yds, at least with the center-fires, and things really start opening up.
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What is this inversion you speak of? I've never heard of it. Got any links?
 
Slash5 said:
..... A .22 bullet takes .068 seconds to get to a 25 yard target, .140 to 50 yards, .292 to 100 yards and .63 to 200 yards.
Drop at 200 yards is about 73 inches.
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I wouldn't have thought it was that much.

How does the 22 WMR and 17 HMR compare at these distances??
 
skeetgunner said:
Doc Sharptail said:
The theoretical progression of groups at differnent ranges is not a straight line mathematical progression- inversion occurs at about 300 yds, at least with the center-fires, and things really start opening up.
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What is this inversion you speak of? I've never heard of it. Got any links?
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I don't have a link for it- you'll have to read up on it in reloading manuals- I came across it in Nosler manual #2, IIRC.

The straight-line theory would have your M.O.A. center-fire doing 3" at 300, which is not the case- the factor changes somewhere past 200 yds, and we end up with groups around the 4"-6" mark at 300.
The point of inversion has the factor increasing from X 2 to X 3 at that point. It occcurs again somewhere past 600 yds. It's been a few years since I've read it- worth looking up though.

Regards,

Doc Sharptail
 
The straight-line theory would have your M.O.A. center-fire doing 3" at 300, which is not the case- the factor changes somewhere past 200 yds, and we end up with groups around the 4"-6" mark at 300.
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If my rifles shot 4-6 inch mark at 300 yards they would be tomato stakes.

Rimfire ammo can be very unpredictable as far as accuracy goes. Serious smallbore shooter not only test the brand of ammo but also test lot #'s to find the best for their rifle, then buy a case or two.
At one time you could sent your rifle to International Imports and Rudy would test different lot #'s for you(for a price of course)

Then they even check rim thickness on every round and batch them in .0005 increments. Even ammo like Eley Club can be made to shoot better if batched like this.
 
I think they went from the short which was too slow,to the long which was too fast to the long rifle to slow it down a bit and then just gave up and went to the 17hmr.
But there is nothing to keep me away from the .22.Sometimes it's accurate sometimes it's not but it's very inexpensive to shoot and the main thing is:I always have fun shooting it.
Good shooting CCIC :wink:
 
I'd be happy with a 4-6" 5 shot group at 100 yards, standing, unsupported. I'm a hunter, so this is the kind of accuracy I'm looking for.
For a bench rifle, Something around 1-2" @ 100 yd would be nice.

Al
 
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