any rule of thumb for sighting in?

[bluebayou]

I was told that if you zero an M4 at 25M then you are dead on at 200M and point blank to 350 (or some such).

If I zero at 25 with a Mosin Nagant then am I good at a certain distance? 

Obviously, I could go and shoot to test this idea...but I only have a 100 yard range locally and I am booked up next week anyway. 

The question arises because I...I mean "someone".....did some filework on a Mosin rear sight.  The rifle was 12" high at 100M.  I tried using shrink to fit tubing on the front sight and that didn't work. 

I got to 3" above POA at 25M.  But now......I am worried that I messed up. 

[bilmac]

I don't know the sight setup on a Mosin, But if you're still high and all the mechanical adjustment has been taken out to lower the rear site as far as possible then fileing the rear is going the right direction. 3" high at 25 is going to take a lot of correction to fix though. You will probably run out of stuff to file off before you can make that big an adjustment.

Older military rifles were set up to shoot way high. The theory was that you would be shooting at a standing man, and so if you aimed at his middle the bullet could rise a long way and still hit him in the head, and then fall a long way and still catch him between the legs. That way the soldier didn't have to be very good at estimating range. This increased the range at which you could hit a standing man to the maximum. It is called the point blank range. Doesn't work very well when you will be shooting at a deer which will have a 16" chest height though.

When I try to make these old fashoned military sights work I try to increase the height of the front sight. Make it taller than you need then file it to adjust. I was lucky on the trapdoor I worked on the front had a pinned in blade that I removed,and  kept, and replaced with a blade I made. I'll bet the front on a Mosin is like Mausers which is a one piece with a ring to fit the barrel with a ramp and then an inverted V on top of the ramp.

If I was you and I didn't care about keeping the rifle in original condition, I would grind the inverted V blade off down to the ramp. Then make a hacksaw cut parallel with the rifle barrel in the middle of the ramp deep enough to put a new blade in. Then find a piece of metal to make a new blade and rough shape it. If you can come up with the right needle file I would widen the hacksaw groove to make room for a sturdier , and more visible blade. You could pin your new blade in but I bet some JB weld would hold it fine.

Take your rifle and a file to the range and file the blade until you are hitting 2 or 3" high at 100. I don't think sighting it dead on at 25 will work with iron sights.

[Singleshotsam]

On an M4, supposedly a zero at 50 yards puts you close @ 300.  Haven't tried it.... yet...

I've heard a lot of different claims about zeroing a rifle @ 25 yards.  My opinion is that its a waste of ammo unless your going to hunt @ 25 yards.  If your going to shoot below 100 yards, sight in for about 100yards.  If your going to hunt out to 300 then zero accordingly per each rifle/caliber. 

Sam

[jgalar]

I have put MOJOs on almost all my milsurps. You remove the original rear sight and install the MOJO in it's place. Its easy to convert back to original sights if you want to sell. The rear sight is a peep that is adjustable for windage and elevation. I highly recommend them!

http://www.mojosights.com/

[Larry Gibson]

The M4s "25 meter zero" when point of aim= point of impact at 25 meters with M855 ammuntion is supposed to give a 300 meter zero (per FM 3-23.3). However, the 25 meter zero is only the first step in zeroing as final zero is found during the "Down Range Feedback" of training when targets at known distance are shot. In other words you should confirm a 25 meter zero by shooting at 300 meters. Yes I know no one in the military (Marines Or Army) does this outside of basic training any more.  I always tried to do it with my troops but I've yet to find an officer who has read FM 3-22.3, or any marksmanship or tactical manual for that matter, outside of those directly involved in marksmanship training.

As to your MN, a POA/POI zero at 25 meters/yards will come close to a 200 yard zero with L type ammo (the 147-150 gr ball) if you are using issue sights.  If you've mounted a scope on it then it all depends on how high the scop is above the center of the bore.  Best advise is, since you've a 100 yards range, is to zero poi 2.5-3" high at 100 yards if you are using 150 gr bullets at 2700-2800 fps.  That will give you a 200-225 yards zero and you will be about 8" low at 300 yards.  If you are using 180s or heavier then zero 3" high. That will give you close to a 200 yard zero and you will be 9-10" low at 300 yards.  Make sure you have the rear sight set on the 100 meter sight setting when zeroing.  and adjust the front sight for windage and elevation.

Larry Gibson

[bluebayou]

Thanks for the info.  I have most everything sighted 1-2" high at 100 for deer hunting (for no particular reason as I am not experienced enough to take 300-400 yard shots, but I figure that it is good habit).

Thanks for the information, Larry Gibson.  I will sight at 100 and see when I get out to the lease.  We have a 300 yard lane where I can set up at known distances.  Will post the results.  I remember now that I had seen some info about the ACOG being setup for 25 yard zero. 

[darrell8937]

Mister  "jgalar"  is totaly wrong! Mojo sights are awefull.. Just send them to me. and all will be well! ...kidding aside.. I love the sight. The dual apeture sight is instinctive! It just looks right. I was amazed at what my M48 Yugo could do at 100 yards. I also have a target trigger.. Hell, this old girl is a real rifle now. And I have the older version.. where you adjust with a allen wrench.. I too highly recomend them.

[iiranger]

#1). Fire your first shots at close range to be sure you are "on the paper." Nothing quite so annoying as firing at 100 yards, walking down there only to ask "where did that one hit..." Spotting scopes save alot of walking, but firing a few at 25 yards or 10 is just too easy not too. Of course, you divide your adjustments ... 1 inch at 25 is 4 inches at 100... like that.
#2). You have three "lines" to think of. i). "Line of bore." You look through the barrel at the target.  "bore sight."  ii). "Line of sight." Since you cannot look down the barrel and close the action and fire the gun you look thru other reference points, sights. iii). "Line of bullet travel"/"trajectory." i). and ii). using light are for our purposes "straight lines." "iii)." is the fun one. To keep this real simple, Weaver used to include an article by Jack O'Connor to help sight in. "Rimfires" were done at 12.5 yards. In those days that meant .22 Long Rifle, High Velocity. Little else widely available. (Shorts were for sissies and girls... like that.) If you survey a strip of land 100 yards long and hang a target 48 inches off the ground, return to the bench 100 yards away, sight thru the bore with rifle "level" at 48 inches off the ground, load a Long Rifle, close the action and fire... The bullet will strike 12 inches below the point of aim. Move back to 125 yards and the bullet strike will be 36 inches low. In brief, the path of the bullet is a curve. The bullet falls from the time it leaves the muzzle and you point the muzzle above the target so it falls into the target... The recommendation was to line things up so the first point where the curve crosses the line of sight is at 12.5 yards. (Rimfires!) Then you will be 1.5 inches high at 50 yards. On again, crossing the line of sight at about 77 yards and only about 2.5 inches low at 100 yards... As I recallllllll

Point, there are tables, I know Hornady has them, in back of loading manuals that will give you the approx's for all the popular cartridges, with the manufacturer's bullets of course. Sectional density and Ballistic efficiency are involved. If you are shooting only one or two guns and with only one or two loads, it is not that challenging to memorize the "Kentucky windage" and/or adjust the scope... Some tape the information to the stock... Luck.

[S.S.]

Rule if thumb...Keep your thumb down or you'll poke your eye out from recoil.....

[bluebayou]

Rule if thumb...Keep your thumb down or you'll poke your eye out from recoil.....

I see what you did there........"thumb" "sighting in" "poke your eye"

[slayer]

I own an M91/30 and would like to use the Mojo Peep. Is the rear site enough or do I need the matching front also? Will the rear Mojo work ok with my existing front site?

Thanks-Jack

[stolivar]

Yes, you do not need the front site also. You can use it without.


steve

[slayer]

Thank you Steve!!