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Elevation Adjustment

Posted: Mon Apr 30, 2012 12:11 pm
by MessEleven
While shooting the Mosin for the first time this weekend, I didn't really make any serious attempts at changing the rear sight. Kept it in the lowest position and shot pretty accurately at 50 yards. But I'm curious, about how many yards (or meters I guess) do each one of the stops represent? Would the lowest stop still be accurate 100 yards out?

Re: Elevation Adjustment

Posted: Mon Apr 30, 2012 12:15 pm
by desdem12
Yes And No. It depends on the rifle. They are in 100s of meters. :D

Re: Elevation Adjustment

Posted: Mon Apr 30, 2012 12:17 pm
by pacanis
Chances are you will be hitting higher at 100 yds than you were at 50, due to the bullet's trajectory.

Re: Elevation Adjustment

Posted: Mon Apr 30, 2012 12:19 pm
by desdem12
I would bet a bag of donuts it is about 6" high and 2 or 3" to the right at 100yds :lol:

Re: Elevation Adjustment

Posted: Mon Apr 30, 2012 12:27 pm
by MessEleven
desdem12 wrote:Yes And No. It depends on the rifle. They are in 100s of meters. :D
Holy cow! So there really is no need make an elevation adjustment on most rifle ranges (at least not at my own club.) I can't see the target much past 300 yards, so how on earth were these Russians able to sight these guns over a 1,000 yards out with iron sights?!?
pacanis wrote:Chances are you will be hitting higher at 100 yds than you were at 50, due to the bullet's trajectory.
Interesting, so the bullet rises. When does that trajectory change?

Re: Elevation Adjustment

Posted: Mon Apr 30, 2012 12:45 pm
by desdem12
I am not sure of the distance these were originaly sighted in for but if it is like most it was likely 300 meters. These were sighted in with the bayonet on. As for now it is a guessing game the first shot. After that you can get an idea of where it needs to be held. Some shoot right on some shoot high and to the right(most). :D

Re: Elevation Adjustment

Posted: Mon Apr 30, 2012 12:57 pm
by pacanis
MessEleven wrote:Interesting, so the bullet rises. When does that trajectory change?
When it starts to fall...

:chuckles:

Sorry to you too, Im bored today :bwink:

There's probably a trajectory chart for the 7.62x54r somewhere. Or someone who knows exactly which caliber it's closest to.
The flatter the trajectory the more accurate over a broader range _without changing aimpoint_. That's why we either tend to sight our guns; 1) where we will be shooting them most from, or 2) where they will impact closest to our aimpoint over a broader range spectrum.

Re: Elevation Adjustment

Posted: Tue May 01, 2012 7:39 pm
by Eljay
So here's ballistics 101 - the sights are set up so that the barrel's actually pointing up a bit, and if it's set to, say, 200 yards it will exactly hit where the sights are pointing at on the way back down. That means there's also some point where it's dead on on the way up! So if you're shooting a rifle at less than, say 100 meters often it's a little confusing.

Military rifles usually have some kind of battlesight zero where they maximize the range over which they're pretty much good enough. If you look at a ballistics calculator with a 200 meter zero and any kind of suitable caliber you'll see it goes maybe a couple of inches above zero, then back down, then out around 300 meters it's still maybe six inches low (just an example - it'll be different for different rounds). So if you're shooting at a person sized target you pretty much set your rifle for a couple of hundred meters and don't sweat it. So I doubt that they spent a whole lot of time actually adjusting the sights - they probably just left it alone and went for it for the most part.

If you go here http://thefiringline.com/forums/showthread.php?t=339204 and look at post #2 and the red line that's what it looks like for a 200 yard zero.

Re: Elevation Adjustment

Posted: Tue May 01, 2012 8:30 pm
by tjtM38
As near as I can tell from the Soviet Mosin Nagant Manual (translated), they fired the rifles at a standard size target, a black rectangle 30 cm high by 20 cm wide on a white shield not less than 1 m in height and .5 m in width at 100 meters on a sight setting of "3" (300 meters). They wanted to be able to hit a man-size target with a standard point of aim all the way to 300 meters.

Re: Elevation Adjustment

Posted: Tue May 01, 2012 8:40 pm
by MessEleven
Eljay wrote:So here's ballistics 101 - the sights are set up so that the barrel's actually pointing up a bit, and if it's set to, say, 200 yards it will exactly hit where the sights are pointing at on the way back down. That means there's also some point where it's dead on on the way up! So if you're shooting a rifle at less than, say 100 meters often it's a little confusing.

Military rifles usually have some kind of battlesight zero where they maximize the range over which they're pretty much good enough. If you look at a ballistics calculator with a 200 meter zero and any kind of suitable caliber you'll see it goes maybe a couple of inches above zero, then back down, then out around 300 meters it's still maybe six inches low (just an example - it'll be different for different rounds). So if you're shooting at a person sized target you pretty much set your rifle for a couple of hundred meters and don't sweat it. So I doubt that they spent a whole lot of time actually adjusting the sights - they probably just left it alone and went for it for the most part.

If you go here http://thefiringline.com/forums/showthread.php?t=339204 and look at post #2 and the red line that's what it looks like for a 200 yard zero.
So in the final analysis, when shooting at 100 meters or closer, you generally have to compensate by aiming a bit low? I actually had the best groupings in my first outing when I did this at 50 yds.

Re: Elevation Adjustment

Posted: Wed May 02, 2012 2:12 am
by tjtM38
Short answer: Yes; with most all my guns, I have to take a six o'clock hold (I'm guessing about 6 inches low) at 100 yards. I have one M91/30 that will actually shoot lower than point of aim at that range, so I have to elevate that sight for 300 meters and leave it for any ranges up to about 200 yards. Every rifle is a bit different, but most shoot high to some degree.

Re: Elevation Adjustment

Posted: Wed May 02, 2012 5:20 am
by Junk Yard Dog
The old Russian saying was to aim for the belt to hit the chest when shooting at short ranges. It works, but sometimes you get a rifle that hits point of aim.

Re: Elevation Adjustment

Posted: Wed May 02, 2012 6:45 am
by audadvnc
Whenever I find myself shooting high, I just eat a big bag of Nachos and read an email from my ex wife. It always brings me down...

Re: Elevation Adjustment

Posted: Wed May 02, 2012 6:51 am
by Junk Yard Dog
:lol: :lol: :lol: Bad :roll:

Re: Elevation Adjustment

Posted: Wed May 02, 2012 3:46 pm
by Eljay
MessEleven wrote: So in the final analysis, when shooting at 100 meters or closer, you generally have to compensate by aiming a bit low? I actually had the best groupings in my first outing when I did this at 50 yds.
You'll have to try it and see for your particular rifle/ammo combo but if you're going a bit high it's easy enough to switch to a six o'clock hold as mentioned above (just aim at the bottom of the bullseye). Note that it might very well be right on somewhere around 20-25 yards as it crosses the zero line on the way *up*.

This stuff can be a bit confusing, but just imagine lobbing a baseball slightly up from horizontal and you'll have the right mental image.

Re: Elevation Adjustment

Posted: Wed May 02, 2012 4:40 pm
by TopperT
I held dead center at the bottom of the man siloutte on this 18 X 12 target. These results are from 100 yards. I was holding a FULL 6 inches low!!!