Thought I had a good load worked out for my .223 reloads for my AR. With my aging eyes and open sights I put twenty rounds into a group the size of a half dollar at 50 yards. Moved to 100 yards and fired twenty more rounds. Walked down to the target, hoping for a decent group, and found that not one round hit the target. Down to ten reloads, and knowing I'm not that bad a shot, I broke out the Tula ammo I had with me. Ten more rounds downrange hit just at the top of the target. I adjusted the front sight until I was consistantly hitting inside the nine ring with the Tula ammo. Then I shot the last ten reloads I had and found all back at the top of the target again.

One of the guys where I shoot said if I increase the powder charge and thus the velocity, the trajectory will flatten and I will start hitting where I want it. He said I should hit high (seven or eight ring) at 50 yards so that I'll be in the bull at 100.

In general, is this correct? Do hotter loads mean flatter trajectory, or is trajectory a characteristic of the round that isn't able to be manipulated?

AR15....16" barrel with a 2.55" sight hight.....standard A2 mil-spec

55 grn FMJBT

50 yard zero

MV of 3000 fps = 1.4 high at 100

MV of 2850 fps = 1.3 high at 100

MV of 2650 fps = 1.1 high at 100


To hit zero at 100 with a 2.55" sight hight and 3k MV you will be .7 low at 50

Faster is indeed flatter but.....

Your gun range guru is wrong on trajectory

That was my mistake, I was thinking one thing and typed another. His advice was, low at 50 to hit the bull at 100. He didn't quantify low, the 7 or 8 ring was my guess. So, faster is flatter, but maybe not enough to explain shooting that high. I wont be able to shoot again for a couple weeks but I'll load some hotter rounds in the meantime.

Hi xseabee,

Do you know what your MV is with your hand loads? That may help you figure out what you need to do.

Same thing happened to me. With factory .223 loads, I was on at 50 yards and again at 300 yards.
The reason? On an AR, the line of sight is at least 2.5" above the line of bore. Thus, you are "shooting uphill" at quite a steep angle at 50 yards.
The cure? As stated above you will have to be low on target at 50 yards.

Remember, with an M4, the design is to have a 62 grn M855 bullet zeroed at 42 m and then again a 300., Hitting a human torso sized target from belly button to upper chest from muzzle to 300m.

Now, if you want to know your "zeros" at intermediate distances, you need to fire at them and record the come ups.

Mostly, one can zero t 150 and be within an inch or two from 25 to 200, with decent ammo like BH77s or Horn Match 75s (or equal loads).

I simply zero at 150 and then confirm POI at 25, 50, 75 100...

I use a 50 yard target at my house, then sight in at the range..my rifles usually shoot from 3 inches to 6 inches high at the 100 yard range..I have not paid all that much attention as I finish sighting in at 100, 200 and 300, and to get it all right at those ranges it takes some tinkering to say the least..If more folks would do this however, their luck in the field would improve to varing degrees.

I tweak my rifles to hit the kill zone with a center hold at those three ranges, 100, 200, and 300 yards, put a little air between the back and the cross hair and you get a hit at 400 yard most of the time, but I don't shoot at game beyond 300 yards, I prefer another 100 yards of hunting..

Faster is flatter.

Since you haven't posted the specifics I made some assumptions: 55 grain FMJ, 3100 FPS.

Zero at 50 yards, 2 inches high at 140 yards crosses zero at 225 yards.

Zero at 300 yards, crosses zero 35 yards, 5 inches high at 175 yards.

So if you were zeroed at 50 yards you should be about 1.5 inches high at 100. If you are zeroed at 300 you are 1.5 inches high at 100.

Now, lets say you are at 2800 FPS.

Zero at 50 yards, 1.5 inches high at 120 yards crosses zero at 190 yards.

Zero at 300 yards, crosses zero 28 yards, 6.75 inches high at 170 yards.

So if you were zeroed at 50 yards you should be about 1.25 inches high at 100. If you are zeroed at 300 you are 4.9 inches high at 100.

balistics and trajectory and all of it is very subjective...... the 21inch guns on the iowa class battle ships would launch a projectile that weighed about as much as a volkswagen to a range of 20 miles and group them all into a target the size of a football field from that far away.....................

quote:

the 21inch guns on the iowa class battle ships

The Iowa class ships all had 16" guns. The largest guns on any naval ship during WWII was the 18" guns on the Yamato of the Japanese navy

quote:

Originally posted by steyrsteve:
Same thing happened to me. With factory .223 loads, I was on at 50 yards and again at 300 yards.
The reason? On an AR, the line of sight is at least 2.5" above the line of bore. Thus, you are "shooting uphill" at quite a steep angle at 50 yards.
The cure? As stated above you will have to be low on target at 50 yards.

Steve is right on this.....The issue is to realize what effect the high line of sight is doing to you.

As to the guy that said to increase your powder charge..... ...wow...be careful who you listen to.

The data I posted above has a 2.5 inch sight height. Be happy to redo with your weight and velocity.

quote:

Originally posted by tasco 74:
balistics and trajectory and all of it is very subjective...... the 21inch guns on the iowa class battle ships would launch a projectile that weighed about as much as a volkswagen to a range of 20 miles and group them all into a target the size of a football field from that far away.....................

ooops.... sorry about that............. you are right i don't know where the 21" came from.......................................................................

At 24 miles, 42,345 yards; 1 MOA is 11.75 yards, 35 feet. If you are at the beach and look outnat the horizon that's 12 miles.

Everyone, thanks for the replies and informaion. I'm sorry its taken so long to reply. I have been working almost non stop overtime the last month and haven't been on line. I did get an opportunity to test five different loads but am no closer to finding a good load thanwhen I started.

From your answers if I'm zeroed at fifty yards
I should be a couple inches, at most, high at 100 yards....well we're talking 8,10, 12" high, so I've concluded that to accurately test my handloads at 100 yards, I need a scope. The longer I look downrange through the peep sight, the blurrier the target gets, so I'm chalking part of this up to my eyes are too old to be shooting 100 yards with open sights. So, next stop...AR scope.

A laser boresighter is helpful with situations like this, so you can see where the bore is in relation to the sight or scope.

Not too big a fan of them otherwise, but the can sure help with the "WTF are the bullets going?" scenarios.