Why an inch high at 100 yards???

W

Watch Dog80

New member
I am curious. They say to sight you gun in 1" high at 100 yards so that you will be dead on at 200 yards. I sighted my gun in dead on at 100 yards which causes me to shoot about 7" low at 200 yards. Can some one explain this to me?
 
What caliber are you shooting? my 22-250 shoots about 3/4 in high at 100 and is dead on at 200. my 223 is about 1.5-2in high at 200 and is dead on at 200 and my 7-08 is about 2-2.5in high at 100 and dead on at 200. not sure who "they" are....
 
Originally Posted By: Watch Dog80I am curious. They say to sight you gun in 1" high at 100 yards so that you will be dead on at 200 yards. I sighted my gun in dead on at 100 yards which causes me to shoot about 7" low at 200 yards. Can some one explain this to me?

Man your gun drops like a rock, what are you shooting?
 
Originally Posted By: nastynatesfishThat load is low for a 270. My brother in law runs 57 gr of 19 and shoots 130 gr bullets.

My book shows the starting load for this setup is 50.6 grains and the maximum to be 59.4, it is a little low but I would not think that it would cause the bullet to drop 7" in any 100 yard distance?
 
Apples and oranges.. I sight my varmint rifles in ~ 1" @ 100 yds.

My big game rifles are set at 3" high at 100..

To get a good feel for where your rifle will shoot a particular bullet you need to know the bullet weight, BC and muzzle velocity.. Then you can use a trajectory calculator to see where you want to sight in at for max effect.
 
WATCH- sight in where YOU like. i do not sight in higher than an inch for fear of shooting over. my experience tells me that is good for me . i have a a couple rifles with turrets for longer shots.
 
You could 'zero' at 100 yards, check the drop at 200, then go to a ballistics calculator, set up for 300 yards, zero at 100, use the same weight and model bullet you are using, then, fiddle with the muzzle velocity number until you get the SAME drop from the calculator at 200 yards as you are getting for real. That will give you a very close idea what your muzzle velocity is. Take that to your reloading chart and verify powder load. NOTE: make sure your barrel length matches the load data chart. You can lose up to 40 FPS for every inch below loading chart barrel length data.

I have a 7X57 that shoots REAL low(10 inches), but then, I'm underloaded from minimum by 3 grains. Long story, chasing a problem. Got it identified and fixed. Now have to restart the load process from the minimum.

Yes, humidity and temperature must be taken into consideration, as well as altitude. (added from follow on question)
 
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Are you putting temperature and humidity into your calculations?

Cold weather (denser air, more resistance) reduces the velocity and your drop will be greater than during warm weather.
 
I am guessing you know this but it is also for others who may not. NEVER load a cartridge under the minimum start load. That is VERY dangerous. I believe it is just as dangerous as too much powder. There is a reason they have START and MAX loads spelled out for you. It is dangerous to go below or above those listed weights...

I hope you do not do that again dogwhacker1. We need all the good guys we can get.
 
Some people prefer to hold on fur out to their MPBR. I perfer to overhold, just what I comfortable with, so I set 1" high and am 1" low at 225. Further out then that and I know I have to overhold. 95% of all my shots though are within that range, so I don't have to think about it or worry about overhold or underhold.
 
watch dog 80:

To answer your question: One poster here presented the acronym of MPBR but didn't explain its meaning = Maximum Point Blank Range.

That is MPBR is the range at which your bullet is no more than 2-3 inches above or below your crosshair, thus on a typical 270 such as yours sighted in to MPBR, the bullet will be almost on at 50 yards, 3 inches high at 100, 2 inches high at 200, and right on at say 250 and say 2-3 inches low at 300 yards ...[more or less].

This allows you to sight on a deer for instance and hit pretty much where you are sighting on the animal/target i.e. use the crosshair on the target, no need to hold high or low off the target. You just place the crosshairs on the animal anywhere from 0-300 yards and you will hit it.

Read up on MPBR in the loading manuals Exterior Ballistics section for various cartridges/animal sizes; it is a pretty effective and straightforward i.e. foolproof system, especially for big game hunting.
 
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I do it the simple way and sight in dead on at 100 and shoot from 50 to 300 yards to see where I'm at. Then anything after that I use the ballistic chart to get a idea. Just remember you have to actually shoot at different distances to know for sure where you will be!
 
I use ar sight for mine. I sifht dead on at 50 yards and that puts me on at about 280. Thats shooting 69gr bullets past 300 ill wait to shoot unless the target is steel and not fur. My 7mag and 308 are hight by 2.5-3" at 100
 
Are you shooting the gun upside down?

Seating the bullets backwards?

Shooting bullets with air brakes?

You'd have a muzzle velocity in the 2000 fps range to get the results you are getting.
 
Originally Posted By: Watch Dog80I am curious. They say to sight you gun in 1" high at 100 yards so that you will be dead on at 200 yards. I sighted my gun in dead on at 100 yards which causes me to shoot about 7" low at 200 yards. Can some one explain this to me?


Iv got a 45/70 that has better ballistics than that. It shoots bricks for bullets
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SUMRIFLE No plans to go UNDER minimum again!!

This was an 'inherited' gun with a custom barrel, that, after inspection and discussion with a gunsmith and personal experience, turned out to be a plain barrel with no chamber work to accomidate the bullet itself!! Of course when your trying to sight it in and the bullet sticks or when it was fired? it broke and stretched every case put in it! Even at minimum, even at -3 grains.

There were 4 problems with this gun; all fixed.

Now have to replace the scope as well.

AND, I had a muzzle brake put on it as well and it STILL kicks like an army mule.

Now that its chambered correctly? Commercial bullets were hitting 10 inches high and my under minimum were hitting dead on. Adjusted for commercial bullets and, you guessed it, shooting 10 inches low on the under minimum.

What a $%^&ing mess that gun has been!!

Ah, but I'll get right for the 'old man' - just because...
 
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