SKS shoots bang on at 25m, but 5" high at 50m?

[Beermaker]

Ignore the haters Quorum. I have had the same issue with sighting in every firearm I've purchased so far. That number is higher than I care to recall in the year's since I've been shooting. (Most have been traded or sold at a loss once they got boring. I don't like to keep safe queens) . Nice thing about the sks was it's cheap to feed and cheap to buy. If the ammo you are shooting is consistent than I wouldn't worry about the POI at 50 yards being higher than expected.

It's likely a combination of point of your point of aim (no offense) and your ammunition. That particular ammo you're shooting probably just shoots a little hotter and maybe the bullet is lighter than whatever ammo is shown on those ballistics charts you looked at.

The biggest issue is the ammo. For me it was most noticeable moving from the indoor range at 25M to an outdoor range starting at 50 yds because frangible ammo was the only stuff they allow at indoor ranges (backstop) and it usually has a lighter projectile than I will shoot outdoors. Not an issue shooting at 25 yards but big differences in point of impact out longer distances with lighter projectile weights vs heavier bullets. I also noticed that when using cheap Norinco milsurp ammo my point of impact was consistently higher than I expected based on the calculations on most charts off google even with the same bullet weight because of the hotter loads in that stuff.

hotter loads. lighter bullets. both will make the point of impact higher.

At the end of the day I found it easiest to sight in at 100 yards with any ammo and then aim a bit high at closer range. That way anything inside 100 yards should to impact low somewhere between the bore and the sight. That's less than a 2 inch window on an sks using irons. How well do you shoot? I'm not consistent enough for that 2 inch window to matter. Just get to know how your firearm shoots each particular ammo and find where you need to hold at each distance to be on target.

+1 Choose a distance to sight in such as 100 yrd/meters. The 25m reference is just there so you know you are going to hit something when you go further out i.e. setting up a scope for the first time etc. If your sights were way off it is easier to correct at a shorter distance. Set the slide on the rear to 1 and adjust from there. IF you are using surplus ammo the shot should hit roughly where you point once the sights are adjusted to you. As you increase your distance and set your rear accordingly the shot should, again, roughly follow. If you are using commercial ammo the ballistics will be differant.

Also concider that wind, temperature, using a bipod etc all impact how the bullet travels and how the barrel and rifle whip and jump.
If your rear sight is on 1 and you hit the target where you want at 25 go back to 100 and confirm and make small adjustments.

 

[mikethebike]

I always sight my rifles in at 50 yards, I never do the 25 yard crap.

 

[plinker 777]

Sighting in a rifle at 25 yards is akin to shooting a pistol at a target 2 feet away (it won't really tell you much...generally) I am aware that Lee Enfields were sighted in at 25 or 50 yards initially but only with a specific type of target that took the ballistics into account out past 300 yards{idiot proofing if you will} (you'll also notice a correlation in that yardage with the sks's battle setting)
I have also heard on this thread that an AR is sighted in a similar fashion, which really perplexes me as I would think the .223 to be a fairly flat trajectory type projectile...but in any event, to the OP; leave the math at home and bring lots of ammo to the range, reach out to 100 yards and dial it in. You'll find that the 7.62x39mm to also be a fairly flat trajectory at these distances. I can tell you from experience that things do change at 300 yards that the Sks sight does not compensate for. A man sized object will certainly receive hits, but 10" groups would require more sight tuning at 300 yards.

 

[Polycoat]

To get a ballpark idea of what the trajectory should be, use a ballistics calculator. Here's an on-line one:
http://gundata.org/ballistic-calculator/

Use the "advanced options" setting to set for a 25 yard zero and the height of the sights above the bore. With the advanced options it also may be useful to set the range and the step size as well.

Here's a good link on how to zero an SKS, in particular, the posts by "D-FENS" are informative.
http://www.sksboards.com/smf/index.php?topic=93204.0

The only thing I would add would be after setting the 25m zero verify the POI's at a variety of ranges, e.g. 50m 100m and 200m. Using the calculator above, a 124g American Eagle 7.62x39 round should be about 1" high at 50 yards, 1.8" high at 100 yards and about 3" low at 200 yards. The far zero is at approximately 160 yards. Sorry for the English units, the calculator above does not give the option of using metric only.

 

[Crazyest Canuck]

It's simple ballistics. In order to hit a target at 100m, you have to arc the shot. It just so happens that on the way up, the bullet will strike the 25m mark as it will at the 100m mark on the way down

Bullets do not arc when being shot. They only have downward pressure from gravity. Listen to Dsiwy state the facts.
Great post Polycoat.

 

[Dsiwy]

People are really over thinking this lol

Zero at 100m with sight set too 100m, adj your 3"-5" group to centre of mass and enjoy you can do fine tuning of the windage at 25m but leave the elevation alone.

If you shoot alittle high at 50m then aim alittle low at 50m, this is a centre of mass gun not a MOA gun

 

[quorum]

To get a ballpark idea of what the trajectory should be, use a ballistics calculator. Here's an on-line one:
http://gundata.org/ballistic-calculator/

Use the "advanced options" setting to set for a 25 yard zero and the height of the sights above the bore. With the advanced options it also may be useful to set the range and the step size as well.

Here's a good link on how to zero an SKS, in particular, the posts by "D-FENS" are informative.
http://www.sksboards.com/smf/index.php?topic=93204.0

The only thing I would add would be after setting the 25m zero verify the POI's at a variety of ranges, e.g. 50m 100m and 200m. Using the calculator above, a 124g American Eagle 7.62x39 round should be about 1" high at 50 yards, 1.8" high at 100 yards and about 3" low at 200 yards. The far zero is at approximately 160 yards. Sorry for the English units, the calculator above does not give the option of using metric only.[/QUOTE]

Not to argue (because I am going to take everyone's advice and re-sight it), but your last sentence is what I'm saying: according to calculators and charts, a 25 yard zero should produce a 1-2" high POI at 50 yards, not 5". I'm assuming that the SKS has poor accuracy due to age and manufacturing technique, but to affirm that assumption, I am just wondering if other people experience the same thing.

 

[mikethebike]

Bullets do not arc when being shot. They only have downward pressure from gravity. Listen to Dsiwy state the facts.
Great post Polycoat.

Its not the bullet that arcs, its the sight that's aimed downwards, so relative to the sight line the bullet does arc.

 

[Polycoat]

Not to argue (because I am going to take everyone's advice and re-sight it), but your last sentence is what I'm saying: according to calculators and charts, a 25 yard zero should produce a 1-2" high POI at 50 yards, not 5". I'm assuming that the SKS has poor accuracy due to age and manufacturing technique, but to affirm that assumption, I am just wondering if other people experience the same thing.

When I read your first post, the 5" value seemed too high. It took me a couple of days to get back to the forum. If I were to guess, I think maybe when you originally zero-ed the rifle, that maybe the rear sight was set for 200 or 300 metres and you didn't notice it. Don't ask how I know these things. That would certainly pooch the elevation adjustment. In the sksboards link I posted earlier, there is a link to the SKS/AK zeroing target. I highly recommend it. I got my SKS zeroed with that thing, and I can get hits on target with iron sights at 100m without trying too hard (and that's with degenerating 50 something year old eyes). In my experience, SKS's are solidly built, a lot of fun to shoot, and are capable of fairly decent accuracy. I am sure you'll get yours running soon enough.

 

[plinker 777]

To get a ballpark idea of what the trajectory should be, use a ballistics calculator. Here's an on-line one:
http://gundata.org/ballistic-calculator/

Use the "advanced options" setting to set for a 25 yard zero and the height of the sights above the bore. With the advanced options it also may be useful to set the range and the step size as well.

Here's a good link on how to zero an SKS, in particular, the posts by "D-FENS" are informative.
http://www.sksboards.com/smf/index.php?topic=93204.0

The only thing I would add would be after setting the 25m zero verify the POI's at a variety of ranges, e.g. 50m 100m and 200m. Using the calculator above, a 124g American Eagle 7.62x39 round should be about 1" high at 50 yards, 1.8" high at 100 yards and about 3" low at 200 yards. The far zero is at approximately 160 yards. Sorry for the English units, the calculator above does not give the option of using metric only.[/QUOTE]

Not to argue (because I am going to take everyone's advice and re-sight it), but your last sentence is what I'm saying: according to calculators and charts, a 25 yard zero should produce a 1-2" high POI at 50 yards, not 5". I'm assuming that the SKS has poor accuracy due to age and manufacturing technique, but to affirm that assumption, I am just wondering if other people experience the same thing.

...No. Who's the candy with the AR in your sig pic?

 

[Ormachek]

Bullets do not arc when being shot. They only have downward pressure from gravity. Listen to Dsiwy state the facts.
Great post Polycoat.

Arc can be defined as "move with a curving trajectory". If that doesn't describe the flight path of a bullet I don't know what does.....

 

[Pistonbroke12ga]

Bullets arc when shot from anything but a level barrel.

 

[ljones]

All bullets arc. They just never rise above the axis of the bore. It always starts at the axis of the bore and drops below it. It can never rise above the bore's axis.

 

[Ormachek]

Bullets arc when shot from anything but a level barrel.

They still arc. Unless you are shooting straight up or straight down, the combination of gravity and air resistance will produce a trajectory with a curve in it, which is an arc.

 

[quorum]

When I read your first post, the 5" value seemed too high. It took me a couple of days to get back to the forum. If I were to guess, I think maybe when you originally zero-ed the rifle, that maybe the rear sight was set for 200 or 300 metres and you didn't notice it. Don't ask how I know these things. That would certainly pooch the elevation adjustment. In the sksboards link I posted earlier, there is a link to the SKS/AK zeroing target. I highly recommend it. I got my SKS zeroed with that thing, and I can get hits on target with iron sights at 100m without trying too hard (and that's with degenerating 50 something year old eyes). In my experience, SKS's are solidly built, a lot of fun to shoot, and are capable of fairly decent accuracy. I am sure you'll get yours running soon enough.

I bet this is the answer. I don't think it was set to 200 or 300 but maybe it was set to 1, or the setting before 1, and then I set to U or something without realizing.