Author Topic: 25 yard zero  (Read 4706 times)

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Redleg

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25 yard zero
« on: November 28, 2008, 03:15:39 PM »
Y'all may have already seen this article, but it is a pretty simple explaination of the the "25 yard zero" using .223, .270, .30-30, 7.62x39, .308, & .30-06.

http://www.modeerhunter.com/stories/zero.aspx

Also, correct me if I'm wrong but from what I've read here on the boards, if I zero my SKS at 25 yards with the rear sight leaf set to the BSZ setting, I should be able to leave it there and engage deer out to 150-200 yards without any trouble.
"The thing that separates the American Christian from every other person on earth is the fact that he would rather die on his feet than live on his knees." George Washington

Greatguns

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Re: 25 yard zero
« Reply #1 on: November 28, 2008, 09:31:13 PM »
Y'all may have already seen this article, but it is a pretty simple explaination of the the "25 yard zero" using .223, .270, .30-30, 7.62x39, .308, & .30-06.

http://www.modeerhunter.com/stories/zero.aspx

Also, correct me if I'm wrong but from what I've read here on the boards, if I zero my SKS at 25 yards with the rear sight leaf set to the BSZ setting, I should be able to leave it there and engage deer out to 150-200 yards without any trouble.

I didn't read the article but I know the trajectory is different for those calibers. .223 has a pretty flat trajectory, .270, .308, .30-06 are similar and .30-30 and 7.62x39 are similar so you are working with 3 different trajectories here.
On the SKS, the BSZ or Battle position(full back) is equal to 300 meters which is about a 20" difference from 100 meters. At 200 meters you have about a 6" drop from 100 meters. If you zero the BSZ at the shorter distance all you are doing is elimanating the usefukness of the leaf from 100 to 300 meters. If you set your rear sight in the valley, the lowest position, and zero it at 50 meters(it should hit about 1" low on the target at 25 meters) it will also be zero at 100 meters. It will then hit about 1" high at 75  meters. That gets you accurate enough for a 6" heart or 8" lung of a deer from 25 meters out to about 150-175 meters without moving your leaf. That is according to the RCBS ballistics chart for a standard 122-125gr 7.62x39 bullet.

Ronny

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Re: 25 yard zero
« Reply #2 on: November 28, 2008, 09:59:34 PM »
I've told this story before, but it's worth re-telling (short version).  An old Army Range Sgt, back in the early 60's, told me if I ever had to zero my M1 in a lurch to do it at 25 yds and then fire for effect out to 300 yds and beyond.  He said that, for all practical purposes, doing it that way would put every round inside a dinner plate out to well over 300 yds.

I tried it and he was right.  A 25 yd zero was around 1 1/2 inches high at 100 yds, about the same at 200 yds and back in zero at around 300 yds.  That was a long time ago, so the figures may be a little off, but the principle is solid.  It really saves a lot of ammo.

I've never tried it with 7.62x39, but I'm sure the principle will work, certainly out to 200 yds, or so.

If you tell the truth, you don't have to remember anything; really helps when you get old.

lonewolf

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Re: 25 yard zero
« Reply #3 on: November 28, 2008, 10:01:22 PM »
Y'all may have already seen this article, but it is a pretty simple explaination of the the "25 yard zero" using .223, .270, .30-30, 7.62x39, .308, & .30-06.

http://www.modeerhunter.com/stories/zero.aspx

Also, correct me if I'm wrong but from what I've read here on the boards, if I zero my SKS at 25 yards with the rear sight leaf set to the BSZ setting, I should be able to leave it there and engage deer out to 150-200 yards without any trouble.

I've sighted in 5 different rifles in 308 and 30-06 rifles with this method and it has never worked for me.

I hit the bullseye at 25 yards everytime, and when shot at 100yds was always way high (5-8"). So I always site in at 100yds.

Ronny

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Re: 25 yard zero
« Reply #4 on: November 28, 2008, 10:37:17 PM »
lonewolf, I've been thinking about it since I posted and to tell you the truth, I believe it was 50 yds now that I think about it (my brain is 70 years old this month).  That would make my recollection of point of impact at different distances make a little more sense, i.e., zero at 50 (30-06) would give about 1/2 to 3/4 inches low at 25, 1 1/2 high at 100, the same or a very little higher at 200 and back to near zero at 300-350.

Thanks for your comment.  You forced me to think about it.

The principle of a short range battlesight zero is still valid, though.
If you tell the truth, you don't have to remember anything; really helps when you get old.

lonewolf

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Re: 25 yard zero
« Reply #5 on: November 28, 2008, 10:48:41 PM »
lonewolf, I've been thinking about it since I posted and to tell you the truth, I believe it was 50 yds now that I think about it (my brain is 70 years old this month).  That would make my recollection of point of impact at different distances make a little more sense, i.e., zero at 50 (30-06) would give about 1/2 to 3/4 inches low at 25, 1 1/2 high at 100, the same or a very little higher at 200 and back to near zero at 300-350.

Thanks for your comment.  You forced me to think about it.

The principle of a short range battlesight zero is still valid, though.

My dad swore by this method to, thats where I learned it from, but after showing him what it did for me, he admitted it didn't work when I did it!!!!

It could all pertain to what type of rifle and the person!!!!!

Josh Maloley

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Re: 25 yard zero
« Reply #6 on: November 28, 2008, 11:28:37 PM »
This will work differently for different kinds of rifles.
It is totally dependent on the height of the sights above the bore.

What holds true for an M16 (.223) with peep sights mounted high above the bore, would not work on a Win M70 .223 with a low mounted scope.

XLT

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Re: 25 yard zero
« Reply #7 on: November 29, 2008, 12:06:21 AM »
The 25 yard zero is a good rule of thumb for sighting in your rifles.  Like the article said fine tune your sights at 100 yards.
Here's a link for a ballistics software that's free from Remington:
http://www.remington.com/products/ammunition/ballistics/remington_shoot_ballistics_software.asp
Winchester and Federal also have similar free software. 
Its interesting to put in different zero and target yardages.

keymastr5912

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Re: 25 yard zero
« Reply #8 on: November 29, 2008, 05:10:58 AM »
thanx for the info xlt. i just downloaded it.

Ronny

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Re: 25 yard zero
« Reply #9 on: November 29, 2008, 10:14:19 AM »
Josh is correct about the height of the sights.  The lower the sights relative to the bore of the rifle, the more near parallel is the line of sight and line of bore.  My reference was to an M1.  Some of the modern rifles (AR< AK) have higher sights and would pattern differently.

The thing to remember is this is not the method you would use to methodically find your correct zero; rather it is a quick and easy method to get it close.  You fine tune from there.
If you tell the truth, you don't have to remember anything; really helps when you get old.

Redleg

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Re: 25 yard zero
« Reply #10 on: November 29, 2008, 06:30:05 PM »

If you zero the BSZ at the shorter distance all you are doing is elimanating the usefukness of the leaf from 100 to 300 meters. If you set your rear sight in the valley, the lowest position, and zero it at 50 meters(it should hit about 1" low on the target at 25 meters) it will also be zero at 100 meters. It will then hit about 1" high at 75  meters. That gets you accurate enough for a 6" heart or 8" lung of a deer from 25 meters out to about 150-175 meters without moving your leaf. That is according to the RCBS ballistics chart for a standard 122-125gr 7.62x39 bullet.

It seemed to me that it would eliminate the need for the 100m & 200m position on the leaf too. So if I zero as you suggest, where will it put me at the BSZ position?
"The thing that separates the American Christian from every other person on earth is the fact that he would rather die on his feet than live on his knees." George Washington