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Old November 20th, 2020, 12:39 PM #21
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Originally Posted by Speed3 View Post
If you were closer to frederick, you could come to my range and we'd get you straightened out quick. Hope someone close can help you
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Old November 20th, 2020, 12:41 PM #22
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You can use a ballistics calculator to determine the offset at 25 yards for any zero range.

I just JBM Ballistics - https://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

So an AR with a 55 grain bullet at 3000 fps, you would adjust your sights so the bullet hits 1.1 inches low at 25 yards, and the rifle will be zeroed for 100 yards.

If you wanted a 200 yard zero, you would set the sights to hit 0.7" low at 25 yards.

The reason you adjust to hit low at 25 yards is that due to the high sight height on an AR, the bullet is rising from below at short ranges.
yea that is something I'm worried about as it's calibered in .357 mag so 100 yrds is effective range even in a rifle and Im not sure of what drop might be can't find any reliable data.
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Old November 20th, 2020, 12:46 PM #23
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Originally Posted by ToolAA View Post
Ammo is freaking outrageous right now. It sucks.

I know resetting the sight to zero sounds like a pain but it’s just sort of one of those necessary steps to make sure you are at least starting off close to the center.

I looked up the specs for your optic. If you bore sight the rifle at 25yds like I described then get back to the range I’m pretty sure you will be on the paper at 25yds with your first shot. At 25yds your 2moa dot covers up an 8” diameter circle. So just grab a paper plate and staple it to a tree 25yds from your window.

At the range shoot at a larger say 16”x16” grid target. Aim right for the center and take a shot. If you to your part and have the gun totally steady you should be able to dial in from there. At 25yds each click of the dial will move the bullet impact 2”. So if your first shot was 6” low dial UP 3 clicks. If the shot was 8” to the left, dial right 4 clicks.

Then take another shot. You should be pretty close to center. Iike some posted above take 2 more shots and measure the center of that 3 shot group and make a final adjustment from the center of that 3 shot group.

If you are satisfied with your result at 25yds move the target back to 50yds. Your shots should be a little lower but still on the paper. At 50yds each click will move the point of impact 1”. So if you are 1” low dial up 1 click. Your windage shouldn’t change.

If you are close to center at 50yds move back to 100yds and do it again. Your first shot should again be low. This time at 100 yds each click will move the point of impact 1/2”. So you may beed to dial up 3-4 clicks to get back to the center. At this point I would take my 5 shot group and make my final adjustment from the
center of that 5 shot group.

This procedure should consume between 12-15 rounds.
On the redialing the specs on my Holosun H403BGR say 50 =/- MOA for travel range which would be 100 0.5 clicks form one side to another yet the following URL for a similiar sight said 372 clicks elevation and 348 windage.

https://unnecessarycomplification.wo...holosun-403gl/
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Old November 20th, 2020, 12:47 PM #24
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Old November 20th, 2020, 07:58 PM #25
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I like to verify the optical plane of the scope vs center line of the bore against a short range target 10-25 yards to make sure they agree before moving to a gridded target at longer distance.(mechanical zero). By firing more than one shot, gross windage adjustments can easily be made at the same time before the scope dials are even involved. Especially if you have windage adjustable mounts.
Once you get paper at 100 yds and your reasonably close, its easy enough to have an assistant adjust the reticule from target center to point of impact while a steady hold is maintained.

Most, if not a majority of manufacture make drums that usually raise POI or move groups right when making anti clockwise adjustments and clockwise to lower or move groups left. (this may not always be the case check your kit but mostly) Your turning the drums toward yourself and not away so its easier if that's what you happen to have going on.

By knowing this before hand, an assistant isn't always necessary and the action can be taken by the firer alone without too much difficultly in many cases by having to maintain a steady hold, or count clicks- perform the action all at the same time.
By having the majority of windage adjustments complete at short range, it usually a simple matter to target the rifle because less clicks are needed for sighting at a greater distance taking into account the difference in elevation only.

The flatter the trajectory of the cartridge that is being used, the easier it is.
For rifles adapted/designed to fire pistol cartridges, the cartridges are usually more abundant than what is commonly used during sighting so elevation corrections could be more drastic, a greater number of cartridges may need to be fired due to the difference in velocity/efficiency at longer ranges.

The more you do it, the easier it usually becomes with a little practice.
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Old November 21st, 2020, 12:01 PM #26
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Originally Posted by wb3jma View Post
yea that is something I'm worried about as it's calibered in .357 mag so 100 yrds is effective range even in a rifle and Im not sure of what drop might be can't find any reliable data.
What round?

Manufacturer will tell you what the muzzle velocity should be. You have to figure out the bullet, but that should not be too hard.

Say Hornady 125 grain XTP at 1200 fps. You are looking at 1.5 inches high at 25 yards, for a 100 yard zero.

For a Maximum Point Blank Range zero, you would set for 2.4 inches high at 25 yards. This would give you a +/- of no more than 5 inches from muzzle to 143 yards.
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Old November 21st, 2020, 05:19 PM #27
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What round?

Manufacturer will tell you what the muzzle velocity should be. You have to figure out the bullet, but that should not be too hard.

Say Hornady 125 grain XTP at 1200 fps. You are looking at 1.5 inches high at 25 yards, for a 100 yard zero.

For a Maximum Point Blank Range zero, you would set for 2.4 inches high at 25 yards. This would give you a +/- of no more than 5 inches from muzzle to 143 yards.
Muzzle velocity of .357 mag rounds are typically my the manufacture given at what the average pistol is. There is some data supporting 1700-1800 fps typically 158 grns) for an 18 in barrel(mine is 18.5) but nothing telling me what you just told me for a .357 mag.
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Old November 22nd, 2020, 10:06 AM #28
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Originally Posted by wb3jma View Post
Muzzle velocity of .357 mag rounds are typically my the manufacture given at what the average pistol is. There is some data supporting 1700-1800 fps typically 158 grns) for an 18 in barrel(mine is 18.5) but nothing telling me what you just told me for a .357 mag.
Sorry, I was basing it off a pistol MV.

For 1750 FPS:

Say Hornady 125 grain XTP at 1200 fps. You are looking at 0.1 inches high at 25 yards, for a 100 yard zero.

For a Maximum Point Blank Range zero, you would set for 1.4 inches high at 25 yards. This would give you a +/- of no more than 5 inches from muzzle to 186 yards.
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Old November 22nd, 2020, 11:55 AM #29
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An innocent question; is it really this complicated?
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Old November 22nd, 2020, 01:11 PM #30
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Originally Posted by outrider58 View Post
An innocent question; is it really this complicated?
Good question Einstein!

I've zeroed alot of guns....havent used a ballistic quotient graph or math yet! :

I ain't that smart.
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