Might belong in the ELR forum, but here goes..

[eastexsteve]

I'll admit that I probably have more time and ammo on my hands than most people. However, these days, I don't think that's such a bad thing. But, after shooting all my life, I took notice of something that has much more effect on long-range shooting than I gave it credit for. To begin with, I sometimes spend an inordinate amount of time at trying to do things with a gun that most people would call a total waste of time. But, I think that this is how you learn things.

Last week, I was running some ammo through my .22 long rifle gun, and learned that I really could hit a 20"plate at 500 yards with my setup. But, even under zero wind conditions, it was incredibly hard to do compared to 300 and even 400 yards. What was most obvious, was my groups (if you can call them that) looked tall and skinny like this:

The above is six hits out of ten shots. (The mark close to the 6-o'clock position is two hits.)

Now, at 300 yards on a 12 inch plate, I can keep them all on the plate and grouped pretty close to the middle between 1 and 2 MOA. At 400 yds on a 16" plate, it gets worse. But, at 500 on the 20" plate, it usually doesn't get any better than what you see here. But, then it occurred to me: that bullet at that distance is coming down at such a down angle, maybe close to 60 degrees. If true, the intersection of the bullet and the plate probably looks more like this:

This would explain a lot when it comes to the compounded difficulty of hitting targets at extremely long ranges. According to this scenario, I'm trying to hit 40 percent less target area than what actually appears in my scope. Here are my shooting parameters:

.22 Long Rifle
Bullet Weight: 40 grain
Muzzle Velocity: 1200 fps
BC: 138
Distance: 500 yards
Zero distance: 50 yards
Holdover: 26 mills with scope mounted on a 20 MOA rail

I invite any comments on this from others who aren't as ballistically challenged as I am. This is obviously food for thought.

 

[Dthomas3523]

ELR is inherently low hit % because of math. Plain and simple.

At those distances, many times the target is smaller than your ES needs for 100% hit probability sans wind, lighting, etc.

So, your hit probability was already pretty low (depending) before the angle of approach vs angle of target is taken into account.

But, this is also nothing new. ELR targets are routinely placed at an angle that matches the angle of approach.

 

[Dthomas3523]

Also, @ 300yds, if you keep track of data long term (like actually track every round), you won’t be under 2moa long term with Rimfire. Just doesn’t happen. AB’s doppler radar is already showing how unstable Rimfire is at that distance.

 

[eastexsteve]

ELR is inherently low hit % because of math. Plain and simple.

At those distances, many times the target is smaller than your ES needs for 100% hit probability sans wind, lighting, etc.

So, your hit probability was already pretty low (depending) before the angle of approach vs angle of target is taken into account.

But, this is also nothing new. ELR targets are routinely placed at an angle that matches the angle of approach.

That's interesting. It's been awhile since I've witnessed anything that would resemble an "official "ELR competition. I've never seen the targets placed at a matching approach angle to the bullet. It seems it would increase your probability of a better score.

 

[eastexsteve]

Also, @ 300yds, if you keep track of data long term (like actually track every round), you won’t be under 2moa long term with Rimfire. Just doesn’t happen. AB’s doppler radar is already showing how unstable Rimfire is at that distance.

.22 long rifle bullets are what they are. Ballistically speaking, not that great. But, I never took much notice how the angle of approach would affect your available striking area. Shooting .22 long rifle at that distance made it obvious.

 

[ma smith]

Were you really holding dead centre on the target and getting centre-target hits (ie, 'no-wind' conditions?)

...even under zero wind conditions, it was incredibly hard to do compared to 300 and even 400 yards...

 

[eastexsteve]

Were you really holding dead centre on the target and getting centre-target hits (ie, 'no-wind' conditions?)

To clarify, there was no "detectable" wind. But, there was the possibility of thermals and wind gusts between the target and myself. I was dialing .2 to .3 mils left. I was assuming that was for spin drift. I haven't tried to do the math on how much spin drift there should be. After all, the cartridge itself isn't known for long range super accuracy. The whole idea of assuming you can achieve that would be silly. I was just trying to see how far I could really shoot it and stay on the plate with some degree of success while the conditions seemed to be good. I was dialing 18 mil on the turret, and holding 8 mil on the vertical subtension. I couldn't dial any more on the turret without giving up some parallax adjustment. It was about .3 mils less than what the software called for on that particular round for those conditions. So, that was really as far as the gun/scope setup could actually shoot that round.

What I was really intrigued with was the amount of approach angle to the target there must be, and how that would affect your available target area.

 

[ballison]

That's interesting. It's been awhile since I've witnessed anything that would resemble an "official "ELR competition. I've never seen the targets placed at a matching approach angle to the bullet. It seems it would increase your probability of a better score.

Actually, the angle of approach for a bullet (even a rimfire) never gets as steep as most people think. Running some quick numbers thru a ballistic app, my 22 rimfire drops an additional 70" from 500 to 525 yards. Doing the math, this puts the angle of approach at less than 5 deg.

 

[308pirate]

Paging @justin amateur

 

[eastexsteve]

Actually, the angle of approach for a bullet (even a rimfire) never gets as steep as most people think. Running some quick numbers thru a ballistic app, my 22 rimfire drops an additional 70" from 500 to 525 yards. Doing the math, this puts the angle of approach at less than 5 deg.

I ran my numbers through ShootersCalculator.com and was getting some very steep angles. I guess you can't trust everything you see on the internet LOL! I noticed the last chart changed the labels for drop from feet to inches. That can't be right. I would believe feet.

 

[DocRDS]

A better way to think about it is there are two "error" or variation sources. One is the dispersion of your shot from POA which is 2-dimensional angular. The other is the dispersion of your velocity which has only a 1-d vertical dispersion (wind would cause it to be 2-d but assymmetrical). As you go to longer and longer ranges this dispersion becomes as large, and then larger than your actual shot dispersion. It has a psuedo effect of "shirinking" the target in the vertical direction. The target is not actual changing sizes, it more to the effect that because gravity is constant (see weaponized math), (target) distance and bullet drop are directly related (bullet distance is related to velocity). So are you go farther and farther out, any errors in distance, both from range estimation and changes in bullet velocity are magnified. (and any change to bullet velocity changes the vertical position of your bullet at distance)

If you had some sort of fictional "HUD" that showed all your errors, it would be circular at 50yds, but by 200-300-400-500 yards it becomes an ellipse with the long axis being vertical.

the rough angle of bullet travel by a crude approximation from the ballistics chart is roughy in 10 yards it drops 15 inches.
360/15 is roughly 3 degrees (its a rough approx) past horizontal.

 

[DocRDS]

also watch the axis of that chart, even in feet its 3:1 , lets say it drops 20 feet in 100 yards.

300/20 = 15
arctan(15) ~ 86

Thus that graph shows the angle is about 4 degrees past horizontal. (and i made the measurment easy by giving extra drop)

 

[W54/XM-388]

You sound like the perfect match for the new monolithic projectiles for .22LR that Geno and Badlands came up with.

 

[Greg Langelius *]

When shooting C/F LR, vertical stringing is usually a product of inconsistent charge weights.

When shooting R/F LR, you're basically swinging in the breeze, because there's no practical way to improve your charge weight consistency.

The cartridge is just not designed or suited for shooting at what would in any circumstance be considered ELR for it.

Greg