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Old November 17, 2008, 08:28 AM   #1
DaveInPA
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.223 Trajectory?

Anyone here an expert on .223 trajectory? I was at the range with my scoped AR yesterday, and with PMC ammo (55gr FMJ), I was dead on center at 100 yards, but at 200 yards I wasn't even hitting a 10"x12" paper target. The gun was rock solid on a good bench rest, and I wasn't jerking the trigger. Does the round really drop off that drastically at 200 yards?

The scope is a Bushnell 6-18 power, turned up to 18x at 200 yards.

Last edited by DaveInPA; November 17, 2008 at 08:47 AM.
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Old November 17, 2008, 08:39 AM   #2
Oberg
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should drop about 2 in if you sight in for 100.. It will have alot flatter trajectory if you sight it in for 200. But as for why you didn't hit the target I couldn't tell you. Are your scope rings tight?
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Old November 17, 2008, 08:45 AM   #3
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I don't know what is the issue, but trajectory is not it. You are dropping maybe 2" to 2 1/2" at 200 yards from a 100 yard zero.

Sometimes folks will cant their sights a little bit to make things "line up." If you cant your sights you can affect your windage zero quite a little bit. Perhaps next time out, be especially certain that the front sight post is sticking straight up.

YMMV. Good luck.
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Old November 17, 2008, 08:46 AM   #4
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Yeah everything is mounted tight, and I can put all my shots in the center of the target at 100 yards all day long. It was kind of windy . . .maybe about 15mph. Could that blow a 55gr bullet that far off track at 200 yards? I'm thinking about taking some 69gr Sierra Matchking bullets out on a calm day and trying 200 yards again.
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Old November 17, 2008, 10:27 AM   #5
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It shouldn't be an ammo problem as the 55gr round will fire out of just about any twist rate barrel. If you zero at 100yds, there should only be about 1.5"-2" drop at 200yds. You should easily be able to keep them on paper at 200yds.

However, you will see a drop of about 8" moving back to 300yds though.

Assuming that everything on the rifle is OK, was it possible you were shooting at 300yds and not 200?
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Old November 17, 2008, 11:01 AM   #6
Brian Pfleuger
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These sorts of things are very handy...


http://www.eskimo.com/~jbm/calculati...raj_basic.html


Though I find that "real" bullets consistently out-perform mathematical models.
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Old November 17, 2008, 11:09 AM   #7
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I zero at 200 and don't have any trouble hitting from point blank to about 300 yards.
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Old November 17, 2008, 11:12 AM   #8
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When I was in sniper school (USAMU Sniper School) they had developed a Sniper/Counter Sniper Guide for Civilian LE Sniper Programs. Back then thats where even the FBI got their sniper training.

The Guide they developed recommended the 223 class of sniper rifle with the ideal that you used the Army's guide in sighting in the 223/5.56. You sighted it in for a battle sight zero of 250 yards. The theory was you could head shoot anyone up to 300 yards by aiming at the mouth, You would never be over 4" high or 4"s low up to 300 yards. I was a LE sniper at the time and carried a Rem 700 Var. in 223. I sighted it in at 250 and using military ball I found it worked as indicated. I had a couple AR15 SP1 Colts. I sighted them in the same way. In shooting a few multi gun and 3 gun matches I found with the 250 zero I was good to 400 yards, just hold a tad higher past 300 yards. Of course this is with the 50-55 grn bullets at the same velocity as the 5.56 Ball. My White Oak Service Rifle Upper is a bit differant because I shoot it differat. Its sighted in for 200 yards, and I adjust the sight for 300, 600 and 1000 yard shooting. I also use 77 grn bullets for 2-300 yards and 80s for 600-1000 yards.

If you are gonna stick to 55 grn bullets, then I think you'll find the 250 zero will work for you in the ARs and Bolt guns.
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Old November 17, 2008, 11:19 AM   #9
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Here's a simple ballistics calculator for you.
http://www.handloads.org/calc/index.html

Using this calculator with zero wind, a 55 gr bullet at the published 3200'ps for PMC Bronze ammo, a BC of 250 which might be high, shows a bullet drop of right at 4 inches for a 100 yd sight in. It could be more if the BC isn't as high as 250. You also have to consider your rifle may not be getting the published 3200'ps or your particular batch of ammo might not be producing 3200'ps. If you can chronograph it, you would have valuable info to help you figure out what is actually happening instead of internet speculation.
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Old November 17, 2008, 11:27 AM   #10
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Should look about like this:

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Old November 17, 2008, 11:31 AM   #11
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I'll throw this in. Its the Bal Chart for Mil Bal 55 grn at 3150 (realistic figure) that I cronied in my ARs. You'll see that if sighted in at 250 yards its 3.27 high at 100 yards, and 3.56 low at 300 yards, which pretty much matches what the USAMU teaches.
You can also see, that in multi gun matchs where the steel plates are normally 18 inches high, by puting the sight at the top of the target, you're still good to go at 400 yards.


Range Vel Eneg Tot dropTrejector
100 2883 1014 -1.8 3.27
150 2756 927 -4.3 3.35
200 2632 845 -7.9 2.27
250 2512 770 -12.8 0.00
300 2395 700 -18.9 -3.56
350 2281 635 -26.7 -8.84
400 2170 575 -36.2 -15.77
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Old November 17, 2008, 11:46 AM   #12
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Dave,

What barrel length is your firearm?

The effect of wind on the 55 is noticeable.

@3200fps your 55gr FMJ with a 15mph crosswind will have 6.4" of wind drift

That 3200fps is in a 24" test barrel. Your AR will no doubt have a lower velocity and as such will be even more prone to wind drift.

J.
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Old November 17, 2008, 11:51 AM   #13
DaveInPA
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It's a 16" bull barrel, 1:9 twist. I really think the wind is the culprit. I'm going to hope for calmer weather this weekend and try again.
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Old November 17, 2008, 11:56 AM   #14
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I think you are correct. Wind is something a lot of shooters fail to take into consideration. It can be fun also. If you can judge the wind take that into consideration and start compensating. Once you can consistently hit in the wind your confidence, not only in rifle but also in yourself, will sky rocket.

Good luck and have fun with you shooting.

J.

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Old November 17, 2008, 12:38 PM   #15
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Try a bigger target so you can actually see where the rounds are going.
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Old November 17, 2008, 12:44 PM   #16
DaveInPA
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My range has small backstops. I'll just have to fabricate some sort of portable larger target backer for myself.
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Old November 17, 2008, 04:14 PM   #17
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Aim at the top of your target, and see where it hits.
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Old November 17, 2008, 10:02 PM   #18
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Which one for a 1/9 twist AR?

Can anyone recommend the most accepted grain weight and bullet tip (hollow point, FMJ, SP) for a 16" or 18" barrel AR?
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Old December 29, 2011, 03:56 PM   #19
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basics

i have a very similar setup with no bull barrel, factory dpms 16inch with a scope, wait for the wind to calm before you fire your group, start at 50 yards and shoot two groups, repeat at 100 yards and compare, if you see a big difference keep in it mind when shooting at 200 but like others said you should be really close, key is waiting for the wind to calm before shooting those groups, but i will tell you this even with 7-10mph crosswind you shouldnt be off by that much, the idea here is to also check your scope and shooter for errors so that we can further help you, hopes this helped, it really helped a friend at the range i ran into. and try a different load, what ammo you using? even the winchesters from walmart do really well if you do your part at 200, il shoot some groups and post them tommorow.
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Old December 29, 2011, 04:40 PM   #20
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When I had a 16 in H-bar with 1 in 9 twist my load was a 69 gr MK or Nosler Custom Comp .I used WW brass and 25 Gr of Varget.Velocity was 2780 .
Varget worked well for me in that load.I make no claim it is the best,but its good.
That load was accurate,clean,and reliable in my rifle.

A real good bet (at least on matters of shooting ;-) !) is to look close at what kraigwy offers you.

Generally,there is not a lot of good reason to zero a rifle to hit point of aim at 100 yds.From that point on,its dropping,Let it be a little high up close at 100,and on at the suggested 250,and you know you are on the target at any range out to 300.

That 15 mph wind not only moves the bullet,if your follow through is not real good,it moves the rifle during that slit second your eyes are closed when you break the trigger.

Focus real hard on seeing the crosshairs,exactly where they are on the target,when the rifle recoils.Call your shot."It was 3/4 in left and 1/2 in low".

Do that every shot ,every time you shoot.See what happens.

One more thing.That is a high magnification scope.Probably has a parallax adjustment.
Two things to consider.Its always good practice to use a cheekweld.That means your face and eye are on the rifle the same way each time.That helps.

When you are down on the bench and solid,Move your eye around a bit behind the scope.Do the crosshairs seem to move around on the target?If so,you found part of your issue.Start with your scope's nominal parallax setting for range.Likely,the best focus is the ideal parallax setting,Verify it by moving your eye around.When the crosshairs hold still,the setting is right.

A little dot of sharpy will remember that range for you.
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Old December 29, 2011, 06:44 PM   #21
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Hopefully he has figured it out in the past 3 years.
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Old December 29, 2011, 11:50 PM   #22
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My chart show the 55 grain at 3200fps will drift 8 inches with a 15mph cross wind value. That would blow you 4 inches off your 8x11 paper if the 11 is vertical.

Sometimes on a windy day I shoot at the windward side of the target, if that puts it on the paper I have immediate visual of how far the wind drifted it.
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Old December 29, 2011, 11:54 PM   #23
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Sorry, you shot 10 wide target, not 8, but aiming at center 8" drift blows you 5" of paper + 3" off paper, or about an inch off if you use the 6 1/4 drift some one called.
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Old December 29, 2011, 11:56 PM   #24
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Any one else learning lots of cool stuff every time Kraigwy posts on here?
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Old December 30, 2011, 12:42 AM   #25
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I favor using a bigger target. Aim for the upper, up wind quarter and correct from there.
If you can't get on a 4' target then there's something wrong with the rifle, scope, or ammo.

That works for me out to 600yds.
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