Joined a club that has a private range stretching to 600 yards this week. Prior to this the range I went to maxed out at 200 yards. Shot a friend's bolt gun and was slapping a 10 inch plate every shot last weekend at the 600.

This weekend I brought my 556/223 AR that has a new 16 in. bartlein barrel in it. I haven't tested every type of ammo through it but I was getting sub MOA groups with 77 grain smk. Less than an inch at 100, and most my groups at 2in or less at 200.

I brought out two 10 inch steel plates, put one at 400 yards and the other at 600.

I was hitting the 400 every shot. The 600 on the other hand was spotty. Probably 50/50 for hits/misses. Most of the misses being barely off of the edge of the plate. Just above, below, left or right.

There was intermittent wind that would gust one minute and stop the next. I have no meter but I'm guessing the gust may have been 10-15mph. It was enough to blow empty boxes, glasses and paper/notebooks off the table. The gusts were at my back, maybe blowing slightly left.

My question is, how much of an impact does the wind have on 77 gr pills at 600 yards? Is 10mph enough to throw my shots off the plate? Having mostly shot at 200y and under, I've never had to consider wind.

I was hoping to ring steel every shot given the performance I was getting at 100-200. I suppose it's possible it's me but I didn't have an issue using a 6.5 Creedmoor on the same range.

Could be the wind, could be that you are getting near trans sonic for a 556 at 600 yards depending on your altitude and temps too, could be you are heating up your barrel.

If you have left-right error, it may be scope cant. Especially if the widest shots also hit low.  Cant is something I was ignorant of for years.  The scope has to be upright or otherwise crooked at the same angle for every shot.

I shoot bench rest with a custom 6mmbra 105gr and that kind of wind will blow it a couple of feet.
Target is 4 x 4. The bipod shooters struggle to get all 5 shots on.
I've had a 2" group right on the edge of the target when i was aiming at the center several times.
No one shoots ppc weight bullets .... Just cant be accurate enough to compete.

What velocity are you pushing?
My 12.5 is pushing 2650 with the can and good on silhouette sized until 800y

Has your barrel passed its break in point yet?

Does it shoot tighter clean or dirty? Was the barrel in its 'best'/zeroed shooting conditions?

Some terrain can create "wind channels" based on hills/backdrops, breaks in the trees, etc. You need to consider the average of all the wind when you start stretching 556. It's small, light, and sheds velocity fairly quickly. Basing 600y off of a bolt 6.5cm as a basis for an auto loading 556 is going to be a rude awakening.

I'll assume you weren't thrashing your barrel, burning through ammo and not letting cool or stay at a consistent temp range.

At 500 yards you need to start knowing what wind is doing at your target. At 600 you definately need to know.

Gusty wind is a giant F you and all your due dilligence. Just the way it is.

You're welcome:

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Dang, I definitely don't feel too bad about it now. I had no expectations going in having not shot that range before with 556. But about 50% of my shots landed on the plate, with most of the others only landing a inch or two off the edge. Based on what I'm reading in here that's pretty good considering I had no meter with intermittent wind gusts that were blowing the tree tops pretty good. Not to mention anything not weighed down on the tables was getting blown away.

Appreciate the re-assurance. I look forward to giving it whirl when there is no wind, the entire range is surrounded by tree lines so normally it is pretty mellow and still from what I've been told. They shoot matches almost every week.

Edit: And I may do some research and invest in a meter.

A perfect 10mph full value (direct left or right) is 7 MOA or 2 Mil. Since the wind isn't a perfect wall all the way, I use about half the perceived windage. So if yours was 15mph half value, that's still 2.5 MOA or 0.7 Mil = 16".

USMC, known distance range in Okinawa spring 2007, first time I’d ever seen a 14.5 M4.

I was shooting a M16A4 with RCO (ACOG) and on that range a RECON unit was also there.  Those guys were mostly junior enlisted and didn’t seem to have much experience with shooing it at the longer distances of our annual qualification.  It was raining and windy for part of that week and they were not happy with their scores at the 500yd line with the 14.5” barrel.

It was that experience that taught me a lot about barrel length, velocity and accurate hits on targets at range.  Even though later our TO weapon was a M4 as aircrew and the same when I picked up SSgt, I always chose the M16A4 over the M4 for qual.

I always got a chuckle when the young Marine working the armory would say something like, “SSgt, you rate a M4, not an A4”. I assured them I knew which weapon I wanted and they’d assign me an A4.

Making sure the scope is leveled is key.  The next piece is knowing that you are actually level when in your firing position.

This is assuming you have consistent fundamentals for everything else.

After that, wind is key.  556 being a lighter bullet will be more effected by wind compared to most long range bullets with more mass or higher BCs.  Light and inconsistent wind is worse for the shooter than high winds at consistent speeds.  

It is hard to hit a small target at long-ish ranges with unknown winds and unknown velocities.  It hobecomes a game of guess and check.

For reference, I complete in PRS style matches with 556 guns on a regular basis.   You will always be outgunned by better performing bullets

For 55s and 62s i say 0, 1/2, 1, 2, 3.  That’s feet of drift in a full value 10pm wind at 100, 200, 300, 400 and 500 yards respectively.

For 77s in I say 0 5 10 20 30 inches.  

It’s rough but easy to remember.   I also shoot shorter barrels.

I know it is controversial here, but I believe the 5.56 is a 400y round that is capable of hits out to 600y in good wind conditions but only with favorable wind and it is akin to a pistol in terminal effect, not a rifle, at that distance. I also have a 16" Bartlein and shoot 77 Sierras.

A 10mph crosswind at 400y is about 17.5" of shift
A 10mph crosswind at 600y is just under 44" of shift

While a pure tailwind is zero value, it does not take much angle to reach a 1/2 value wind holds. A 5mph wind velocity change from a strong gust OR a lull in wind OR a shift in direction from 1/2 value to zero value at 10mph will move the bullet about 4" at 400y and about 11" at 600y. That extra 5" one way or the other is a killer at long range on small targets.

Also, 6 MOA is not 36" at 600 yards, it is close to 38 inches. And with a 16" barrel you are probably getting more than 6 MOA drift like me. A caliber change will help that, not 2" of extra barrel length.

I shoot a lot of 77’s at 600. If you were hitting 50% in a 10mph cross wind and the others were near misses on a 10” plate you are doing pretty good. In favorable wind conditions I have stacked 10 Berger 77 tactical’s into 5” at 600. I was thrilled!

Last time I went out there was a guy there that has competed in PRS for years. He volunteered to spot and called wind for me and I was able to land a 5 shot group within 4 inches at 600. After that experience I'm convinced that a mediocre shooter with an expert spotter could shoot lights out.

Don't think I could repeat that group out on command but it made me feel good for one range trip anyways.

In the mean time I picked up a kestrel, some surveyor tape to read wind, and a spotter scope. I know 5.56 isn't ideal but I'm starting to warm up to the challenge of it. I'll be picking up a 6.5 bolt soon but I'll keep shooting 5.56 to earn some experience dealing with wind. I also have a new found respect for spotters/shooters that shoot long range.

I started 600 with a 223. When I got my 260 it felt like cheating. The 223 is a great round to train with at that range.

Enjoy!

That’s why in the classic sniper/spotter teams, the spotter was almost always the more experienced shooter!

Yeah, sounds like you had at least a 12mph wind at half-value (1-2 O'clock) so maybe 3-4 MOA windage with the 77's. Sounds like you were just off the 10-ring (2 MOA) so a pretty good job at "winging it".

View of the 600 yard line at out monthly NRA match MCB Camp Pendleton, San Diego

Nice! I used to fly scale models at Pendleton with Col Thacker. Pretty darn cool place.

Maybe he's still flying, we see a red RC plane flying on Sundays out by Camp Horno, 53 area.

Probably one of his buddies. He died two years ago.

THIS

<This.

Champions choice still carries those cards. They have 308/223, either 1/2 or 1/4 MOA sights, choice of bullet weights, etc.

https://www.champchoice.com/mc-range-equip/wind-meters-wind-charts/

This works pretty good for me . Shooting 77smk. It’s just the old wind  formula out of my big green usmc knowledge book with the math pre done and put into a chart. It’s not perfect and not 77 grain specific but I find it works none the less to get on target quick.

Remember , if it’s a 1/4 or 1/2 value wind  just half or quarter the numbers seen on the chart.

Values are in MOA for people shooting MOA scopes or A2 iron sights , just a FYI

If you shoot at say 600 and you find where you are on the wind chart you can then just step it up to 800 and you will know what you need to hold.
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