Understanding Long Range Shooting. Question.

It's almost impossible to say ..it would be best if you could link up with a good shooter someone shooting 6" groups at 600 yards consistently and have them watch your technique and look over your ammo and set up

 

Heck, even holding your tongue differently changes things
This is where practice come in and changing things around to see what works and what doesn't. Coaching from a good experienced shooter on all aspects is highly recommended!

 

I started my students with an air pistol to learn sight alignment and trigger control. After that I taught proper rifle positions. I did not teach bench shooting. But I learned to shoot off sandbags in the Army. I am saying make sure you have the proper basics. from there it is a steady position when you pull the trigger. You have to take into account follow through and recoil as well. As someone said, poor basics have poor results. Poorly set up rifle, poor position, flinching and rifle or scope cant can all hurt.

 

Having an experienced shooter to help evaluate you is invaluable. But how/what you evaluate is also key.
In the manufacturing world I work in, we're tought to solve problems by assessing 3 main aspects of production: Man, Method, and Machine. If you handload, you would apply this to your handloading and your shooting.
The "Machine" part of this hobby is probsbly the simplest, but not always the easiest: Gun, sights, scope, rings, mounts, barrel, stock, trigger, bullet, brass, reloading press, powder measure, powder, primer, bullet speed, etc...
Any one of these is a variable that can seem fine at 100yds and show otherwise at longer ranges.
Then you have the "Method",
Anneal brass or no, neck size or FL, trim or no, new brass or range pick ups, fireform or no, powder drop or hand weighed, bags or bipod , prone or bench rest....
Then you have the Man, which hopefully applies more to the shooting than to handloading:
Tall or short-correct length of pull, eyesight, cheek weld, trigger pull or squeeze, shoulder contact, shooting position, breath control, muscle control....

In the mfg world, we usually pick the easiest (or cheapest) to fix first from each category and work up the list.

There's a lot of details we don't have that would help others to help you.
But I'll throw out a few thoughts anyway:
.... I infer from what you didn't say that you have acceptable groups at 100yds, but you are inconsistent at 200yds plus. If I inferred in error, then you need to back up to 100yds and figure out how to get that under control.
If you are consistently getting moa groups at 100 and can't stay inside a 3" target at two hundred yds, then you likely have a bullets stability problem or an optics problem.

Maybe some pics of your 100yd and 200yd groups would be good to help you assess things.

 

How far are you shooting the .223? Shooting 200 shouldn't be a problem. The thing is, the farther you shoot, you are introducing a variable that has exponential effects. The wind. I shoot to 300 with an AR and 4X scope without too much trouble. Beyond that, you're getting technical. Wind has a bigger impact and using projectiles with a higher ballistic coefficient helps immensely. I'll shoot 55 gainers out to 300, but beyond that I want 69s and then 77 or even heavier out of a bolt gun.

How small are the targets you're shooting at? I strive for MOA accuracy. I try anyway.

Shooting a .223 out to 300 is harder than shooting a .308 out to 300. Shooting a .223 out to 600 is like shooting a .308 out to 1000. There is voodoo involved.

The next time you go shooting, maybe set up some wind flags along the way. See what the environment is doing.

As for technique, check out the snipershide website. They have some training videos that are pretty informative. Pay attention to the stuff on body mechanics.

 

If memory serves, some of his posts have shared ~1moa groups delivered out as far as 500yrds. 223 can reach a lot farther than just 200, which seems to be the OP’s intentions - although we haven’t heard back from him for quite some time, compared to his former responsiveness on his threads.

 

Assuming the rifle/scope/ammo is all in good working order and they all get along with each other, and the correct data is applied, its always proper execution of the basics and consistency in doing it. The longer the distance, the more important all of this becomes.