Accuracy at 100, 200, 300 yards????

[l98ster]

Hi everyone,

I'm just about brand new to rifle shooting, although I have been shooting shotgun and pistol for years. Anyhow, if I create a load (.223, 55gr) and it is accurate at 100 yards (1 MOA or less), does that mean I can expect about the same accuracy at 300 yards?? I know wind and drop compensation is involved, but I want to know if a bullet can stabilize at 100 yards, but destabilize after that?

Basically, am I going to have to come up with different loads for 100, 200, 300 yard targets?? I ask because my local range only has 100 yard targets, and when I do have the opportunity to shoot somewhere else at longer distances, I would like to know that my load is capable.

Thanks!!!
-George

[zoomie]

100-300 should be about the same. If you start talking farther when the bullet is transonic, then all bets are off. Find an accurate load at 100 and shoot it progressively farther until it falls apart. I bet it'll be well past 300.

[Art Eatman]

My .223 bolt-gun is half-MOA at 100 yards, and minute-of-prairie dog at 300.

Prairie dogs are not what you'd call big.

[TxFlyFish]

I find that sometimes things don't seem to stabilize for me till past 300yds. My 500yd shot on the AI is better MOA wise than my 100yd shot

[geetarman]

I find that sometimes things don't seem to stabilize for me till past 300yds. My 500yd shot on the AI is better MOA wise than my 100yd shot

I have difficulty understanding how that can occur. I have seen more than one post on the subject but it still puzzles me how a bullet can be unstable at 100 yards and then stabilize at 300 yards or so.

It just seems that unless bullets have some sort of rational grouping at 100 yards, why would one move out to 300 yards to see if things are better?

In my mind's eye, I am seeing wobbly bullets at 100 yards going all over the place and then by shooting out at a more distant range, the bullets manage to converge and group well.

More experienced shooters will probably chime in and point out the error of my ways

Please understand that I am not trying to be critical, I just do not see how it can happen.

Geetarman

[mehavey]

It's not that a 2-inch group at 100 yards becomes a 1-inch group at 300, but rather that a the
angular dispersion can "settle out" and grow at a slower rate as the bullet's initial yaw
and precession/nutation settle out.

That group at 300 is therefore not directly proportional to the group at 100 multiplied by the
ratio of ranges. Instead, that 2" group at 100 might grow to only be 5" (instead of 6") at 300 yards,
and 8" (instead of 10") at 500, (etc, etc)

[HJ857]

Basically, am I going to have to come up with different loads for 100, 200, 300 yard targets?? I ask because my local range only has 100 yard targets, and when I do have the opportunity to shoot somewhere else at longer distances, I would like to know that my load is capable.

Zoomie is on the right track here.

Also, it will depend on how far you figure on shooting. If up to 600 yards then you have a lot of load options, if further than 600 yards then your choices narrow a lot.

If within 600 or so yards, one load is all you'll need. The common wisdom is that a 69 grain bullet is the best option. For my use I've found the 53 grain Vmax is the best bullet out to 550 yards. You'll need to consider your barrel's twist rate too when selecting bullet options.

A chronograph will help you a bunch and eliminate a lot of testing. Once you get a good load, and determine it's velocity, then you can apply that data in a ballistic calculator and that will give you drop and wind calculations, as well as at what distance the bullet goes transonic.

Gravity is a constant, therefore bullet drop is also a constant, once you figure it out it doesn't change ever. So it's pretty easy to figure out where the bullet will impact at any distance. But you must know what your muzzle velocity is to obtain good data.

Wind is another story. Wind is calculated assuming it's a constant speed at a constant direction all the way from the muzzle to the target. It's rarely, if ever, that simple. But it's a good starting point.

You'll also run into the term "balllistic coefficient". This is a term specifically for bullets. Generally speaking a higher BC is better. On the other hand a lighter bullet that has a lower BC but travels faster will be better than a heavier bullet with a better BC traveling slower, but only up to some distance. As the distance increases, the heavier, slower bullet will begin to perform better. Generally speaking 600 yards is the crossover point where the heavier bullets start to win out.

The ballistic calculators are nice because you can do a lot of "what-ifs" with them, plugging in various bullets and velocities and see what happens without having to actually load and test an endless number of configurations.

This is a simple calculator that works really well.
http://www.handloads.com/calc/

This is a more detailed set of calculators.
http://www.jbmballistics.com/ballist...culators.shtml

[big al hunter]

I believe most accuracy changes from 100 to 300 yards are caused by the shooter or the scope. If the shooter is the problem it could be technique or the bench is shaky. If it is the scope, it is usually caused by parallax. Parallax is a phenomenon common in all optical systems that have a cross hair. It is easy to see at the range. Get your gun settled on sandbags or whatever rest you have. Look at the target and move your head around without moving the gun. If parallax is present you will see the cross hair move on the target. Every manufacturer has a distance that they set for parallax free, most are 100 yards. You can get a parallax adjustable scope for a little more money. Most people don't need to adjust it, but if you are looking for tack driving accuracy at all distances it may be worth getting. Technique is something best learned by experience and hands on training with someone that is a wise and learned shooter. Best of luck and may every shot go where you want it to.

[jehu]

Use your 223 for 200yrd and under, get a 22-250 for over 200 IMO. Yes 223 will kill over 200yd but really starts to dive at 250+.

[Art Eatman]

My 100-yard benchrest is on my front porch. I have a 500-yard table right by the house, 90 degrees from the other range.

My pet '06 was always reliably just under one MOA at 100. I got two 0.8 MOA groups with it at 500 and figured that was good enough. That was back in 1997.

Haven't worried about downrange effects after 100 yards, ever since. I keep hitting critters at 200 and 300 yards, so why over-think the deal?

[geetarman]

Art,

I hear what you are saying.

Somehow the image of a DNA helix springs up in my mind and I just have a terrible time thinking bullets that are not grouping at 100 yards magically come together at 300 yards or farther.

There are some very experienced shooters who describe the kind of thing being discussed. I just have not been able to wrap my arms around it.

I am smart enough to believe in continuing education

When I used to shoot groundhogs back in Illinois, I only cared where the first shot went. When I developed my loads, I would sight in at 200 yards and figured my groups were tight enough to dispatch them when I saw them in the bean fields.

The more I learn, the more I know I don't know. ( I am NOT Dick Cheney)

Geetarman

[mehavey]

Somehow the image of a DNA helix springs up in my mind and I just have a terrible time thinking bullets that are not grouping at 100 yards magically come together at 300 yards or farther.

Take a look at this illustrative video from Berger....

http://www.youtube.com/watch?v=KH9SC...yer_detailpage

...to get a sense of a bullet left "gyrating" from muzzle effects, "settling down" after 100-150 yards.
[/B]

[Pathfinder45]

We had a thorough discussion of this subject a couple of years ago in which we arrived at some conclusions about the observed phenomenon of some load/rifle combinations that deliver smaller MOA groups at longer range than they will at shorter. Many could not believe it at first........ Here's the link: http://thefiringline.com/forums/show...ght=stabilizes

[geetarman]

Mehavey,

Thanks!! That clears a LOT up. I appreciate it.

@Pathfinder: I see that I posted in that thread also. Thank you!

Geetarman

[Pathfinder45]

1:Anyhow, if I create a load (.223, 55gr) and it is accurate at 100 yards (1 MOA or less), does that mean I can expect about the same accuracy at 300 yards?? 2: I know wind and drop compensation is involved, but I want to know if a bullet can stabilize at 100 yards, but destabilize after that?

3: Basically, am I going to have to come up with different loads for 100, 200, 300 yard targets?? I ask because my local range only has 100 yard targets, and when I do have the opportunity to shoot somewhere else at longer distances, I would like to know that my load is capable.

My Answers: 1. Not really. It's often amazing how a load that shoots well at 100 yards will be all over the paper at 300 yards. What's more astonishing is when a mediocre load at 100 yards delivers sub-MOA at 300. 2. Yes, bullets can destabilize over distance. 3. Maybe. If you are shooting for score in competition with others and want to win, then probably yes. However, for hunting, it's often more practical to find the one load that shoots best at long range, (say, 300 yards?), and be willing to accept whatever it gives at shorter ranges. Good 100 yard groups do not guarantee acceptable results at 300 with the same load. If you expect your rifle to perform well at 300, you have to shoot it at 300.

[Bart B.]

It's been my experience that groups at 100 yards open up about 10% for each 100 yards further down range. A 1/4 MOA rifle at 100 yards will be about a 1/2 MOA grouper at 600 yards; providing muzzle velocity spread's under 25 fps and they stay at least 50 fps above the sonic barrier enroute to the target. Muzzle velocity spread, small varibles in BC caused by normal unbalance in bullets and subtle cross winds are common causes.

There's two ways a buncha supersonic bullets will group smaller at a further range than a closer one.

First, the issue SMLE .303's had in long range matches with arsenal ammo. Their extra whippy barreled actions launched slower ones at a higher angle than faster ones. At short range this increased the vertical shot stringing on paper. At long range, the groups were smaller; faster bullets left at a lower bore axis angle and slower ones left at a higher one. This is called positive compensation. It's been observed to a small amount testing M14NM competition rifles in accuracy cradles and is caused by the gas port being near the middle of the barrel which bends the barrel a tiny bit. Front locking bolt action rifles sometimes do this a small amount depending on muzzle velocity and how whippy the barrel is.

Second, all fired bullets have to be self controlled and know exactly where they are relative to the mean trajectory axis of previously fired bullets by special internal sensors. If one's low and to the right half way to the target, it "knows" is has to make its guidance system change its directions a little bit up and a little bit to the left to strike the center of the group further down range. The actual physics of how they change direction must be classified 'cause it's never been published.

[geetarman]

Second, all fired bullets have to be self controlled and know exactly where they are relative to the mean trajectory axis of previously fired bullets by special internal sensors. If one's low and to the right half way to the target, it "knows" is has to make its guidance system change its directions a little bit up and a little bit to the left to strike the center of the group further down range. The actual physics of how they change direction must be classified 'cause it's never been published.

That sounds serious....

I am using a false ID...just in case

MandolinMike

[Pathfinder45]

This is too much for me:

Second, all fired bullets have to be self controlled and know exactly where they are relative to the mean trajectory axis of previously fired bullets by special internal sensors. If one's low and to the right half way to the target, it "knows" is has to make its guidance system change its directions a little bit up and a little bit to the left to strike the center of the group further down range. The actual physics of how they change direction must be classified 'cause it's never been published.

[Art Eatman]

"...it's never been published."

That's because the security classification is "Burn before reading".

[BigMikey76]

That's because the security classification is "Burn before reading".

Does that mean I have to incinerate my computer monitor now? Cause I'm at work, and I don't think my boss would like that...