# Puzzled



## topside1 (Sep 23, 2005)

I've been shooting rifles since I was 12 so I'm very familiar with many types of firearms. So here's the question I'm shooting a C93 chambered in 5.56 and have it dialed in perfectly at 50 yards from my target. Whenever I move up to the 25 yard line and fire bullet point of impact remains true left and right, but falls low by two to three inches. Rifle outfitted with red dot optics 1 x 35mm. Why does this happen?

Maybe all my rifles do the same thing however I never shoot a hunting rifle at 25 yards to find out. Sure hope I don't look to silly asking this question, bring on the answers....Topside


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## GTX63 (Dec 13, 2016)

Is this your rifle?


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## topside1 (Sep 23, 2005)

yes


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## GREENCOUNTYPETE (Jul 25, 2006)

Sight height over bore axis is the reason.

you don't see it on most 22lr or win94 and such because the sights height is onlu about an inch over bore axis

but we see it a lot on AR15 and other guns with a high sight axis

I am also going to guess you sighted in at 100 yards , which makes this worse

your sights are 2 1/2 to 3 inches higher than bore axis with a red dot mounted on that rifle

at 100 yards your bullet has gone up hill that bore to sight distance and hits where you aim but at 25 yards your bullet has only come up 1/4 the total distance to your sight and why you hit low.

if you sight in to be on at aproximatly 50 and 225 you will be about 2 inches high a 100 but you will be much closer at 25 as well as not being below the point of aim until you reach beyond 225 yards


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## topside1 (Sep 23, 2005)

Wow great explanation, and yes sighted in at 100yds doubles the drop at 25yds. Here's my troublemaker. Love the rifle quite honestly........ Thanks again, I never knew.


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## GREENCOUNTYPETE (Jul 25, 2006)

I am having difficulty posting pictures today , but if you go to https://www.hornady.com/team-hornady/ballistic-calculators/#!/
enter in a BC of .246 a velocity of 3000fps , bullet weight of 55gr , a sight height of 2.7 or whatever you measure yours to be and a zero range of 225 yards you will likely start to see. if you could graph that data you would see your arch vs your line of sight.

you look strait like a lazer , but your bullet starts 2-3 inches below your sight then travels above your sight then back down through your sight as it losses velocity.

if you think of it more like a foot ball you look at a point about 10 feet above your friends head and through the ball there but it travels up then the effects of gravity and loss of speed bring it in an arc down to your friend and he catches it , because you can't throw a foot balls , a spin stabalized projectile at hundreds of feet per second it must take an arc and not a strait line even if your friend is only 30 yards away.

for a hunting zero or a low power red dot a 50 and 225 yard zero is about ideal that way the highest your bullet is above your sights is around 2 inches and the lowest it is is around 2 inches from 10 to 260 yards meaning that if you keep your shots inside 260 yards you needn't really worry about range estimation or adjustment provided your target is 4 inches or bigger vertical.

a BSZ battle sight zero is typically set at 25 yards or 25 meters , 75 or 82 feet.
in dooing so your exactly on at 25 yards 

25y 0
50y +2
100y +6.5
150y +9
200y +10.3
250y +9.9
300y +7.5
350y +2.8
400y -4.5

a typical enemy combatant target target is 16-18 inches across the shoulders and around 17-20 inches from navel to neck if your sight is placed about 1/3 up the torso from the belt on a standing target it is a hit from 0 to 400 yards no math for solders is ideal.


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## D-BOONE (Feb 9, 2016)

Oh my god its a dreaded black assault rifle RUN RUN FOR THE HILLS!!!!!! QUICK BAN IT!!!!WEAPON OF MASS DESTRUCTION. AHHHHHHHHHHHHHHHHHHHHHHHHHH


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## GTX63 (Dec 13, 2016)

When it comes to firearms, dumbs questions are often the first ones that should be asked.
I went thru the same frustrations when I first started using ARs.
They were the first elevated sight rifles I had ever used and I muttered and mumbled quite a bit on my gun range before I mustered up the humility to get an old buddy to explain to me in person what I couldn't sort out reading on my own.
Once I figured it out it was embarrassing.
Of course the first time I took my son hunting with an AR he dropped a squirrel at 75 yds on the first shot....


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## topside1 (Sep 23, 2005)

Yes I have zeroed in at 25yards and then marched backwards to 100yards what a dramatic difference. All my shooting lanes are woodland, and less than 100 yards and that's why a sight this particular rifle in at 50yards. This problem has irritated me for years and i nearly traded her in, puzzled no more...Thanks


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## Chuck R. (Apr 24, 2008)

Try this type of "zero" while it's not correct for your HK clone. It compensates for the "delta" of bore and sights which is commonly referred to as "offset". It will give you an idea of how the barrel sight/offset is accounted for at the closer distances.











Most of the ballistic software available will calculate your POI at distances once you type in your sight height, MV, bullet weight or BC, etc.. That will give you a solid idea of your 25yard POI VS POA with a zero at whatever distance you wish. You can then create you're own 25yd "zero" tgt for your rifle that accomplishes the same effect as the picture above.


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## topside1 (Sep 23, 2005)

Worthwhile update: Today I tested sight height over bore axis with my scoped Ruger 10/22. Sure enough @ 50 yards spot on, and at ten yards several inches low. Adjusted elevation to a reasonable compromise. I'm learning.....Topside


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## GREENCOUNTYPETE (Jul 25, 2006)

try bringing the zero in to 25 yards

say you have 2 inches from bore to center of the scope.

if you zero at 25 yards it will be about 1/2" high around 35 yards and 1/8 inch low at 50


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## topside1 (Sep 23, 2005)

I understand Green Pete, I will make those adjustments. The little 10/22 is one sweet shooter, cheap shooter too.


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