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Best zero distance for bullseye pistols.

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impalanut
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Best zero distance for bullseye pistols. Empty Best zero distance for bullseye pistols.

Post by Wobbley 7/7/2021, 5:09 pm

As a relatively new shooter, my quandary was where to zero my bullseye pistols for elevation.?  By “zero” I mean where you mark your sights to establish a “mechanical” zero.   The majority of the shooting is done at 25 yards, but zero is likely far more “important” at 50 yards (or is it, since you can always adjust in Slow fire when you can’t in sustained.)   Hence the quandry. 

So, being an enginerror I thought I’d try some math/logic.  So I turned to Strelok and other ballistic apps using normal velocities for 22 at 950fps, 38 at 775 fps, and 45 at 725 fps.  I used ballistic coefficients as published for Hornady bullets as representative.  It turns out that if you zero at 40 yards (or thereabouts) the come-up to 50 yards is about 2MOA.  The drop down to 25 is about 2 MOA.  So, if you zero at 40 and shoot enough to get a good true zero, like 25 rounds or more, you could mark your sight, then come up 2MOA (2 clicks on a lot of sights) for 50, then down 2MOA for 25.  The idea here is that even if you forget to move your sight you’re still in the 9 ring.
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Post by SteveT 7/7/2021, 5:21 pm

Sometime a long time ago I heard someone say "zero at 50 yards and adjust down to 25". I suppose that will be more accurate than going the other way, but after shooting a few matches you should know what the adjustment is. 

I don't mark zeros on pistols. I rarely adjust except going 25 -50 yds. I used to put paint marks at 25 and 50 settings, but they wore away and didn't need replacement. I keep my CF guns at 25 yards, which also works for 50 feet. Adjust up to 50 yards, then back to 25 yards and leave them there until the next match.

22's don't need adjustment from 50' - 25 yd - 50yd. If I am really shooting well I come up 2 clicks at 50 yards which means center of X ring instead of an inch down in the ring, but it's been a long time since I thought that would make a difference in my score.

FWIW when I was a new shooter (and not so new) I was much too willing to adjust the sights. I don't know how many matches I had 2 or 3 shots in one direction so I adjusted. Then the shots started falling the other way and by the end of the match I was within 1 or 2 clicks of where I started.
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Post by LenV 7/7/2021, 5:48 pm

I have shoe tags I use to keep track. My pistols all look like they have sales tags. In realty the tag tells me what distance it was zeroed too when boxed. Too many to try and remember. Heck, two is too many.
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Post by chiz1180 7/7/2021, 6:20 pm

If I am zeroing a gun, I start at 25 and confirm at 50 with the approximate adjustment I believe is required. If you are not hitting paper at 25, more than likely will not be at 50. I keep small notebooks with each gun and record relevant changes/sight adjustments and other important info (cleaning, parts replacement/adjustment, etc.) I also zero off hand, not from sandbags.

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Post by SilentAssassin 7/7/2021, 6:50 pm

Your sight height relative to the precise measurement to the center bore axis is going to have a lot to do with what you are trying to accomplish. A LOT.

To do this and get an accurate measurement, one will set up a box with a target. Fire a shot at that target from about .........as close as you can get. Aim at the center of the target with your red dot ,  from one yard or less and fire a shot.

Then measure the fired shot...........to the center target that you were shooting at.
This will give you very near your exact sight height.
Then plug that into strelock.Everything you've calculated to this point will change.

Without this measurement, you are playing a guessing game with computation.

If you really want to go in depth with this. Like I sometimes do. You will chronograph the ammo you will be using at a near distance, and then a far distance.
This will require a mean average which means be prepared to sit there firing at the chrony in a series of shots one and two ( near and far) then calculating THAT average. Since most often no two shots are going to measure the exact same speeds. In other words, take your near 10 shots speed, add them, then divide by 10 - use the sum as an average. Same for the far shots. This will get you very close to where you want to be as far as computer tuning your gun goes.




SA.

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Post by impalanut 7/7/2021, 8:14 pm

I zeroed my matchguns with aimpoint h2 off a rest (not a ransom) at 25 and 50 yards.
once zeroed at 25y it required 8 clicks up for 50y. off the rest my groups were about 2" at 50y

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Post by CrankyThunder 7/7/2021, 8:19 pm

zero at 25 yards.  Its zeroed at 50 foot.  

At 50 yards, hold top of bull
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Post by Axehandle 7/8/2021, 4:20 am

Smile "Mechanical Zero"    25 or 50 doesn't matter.  What I think you need to know is where ever your zero is you need to know how many clicks it is to bottom out the screw.  If you know that you always know how to get back to your "mechanical zero"

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Post by DA/SA 7/8/2021, 4:41 am

If there is no change needed between 25 yard and 50 yard shooting, zero at 50 yards.

If a change is needed between the two, it really doesn't matter, as you will be adjusting anyway.
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Post by WesG 7/9/2021, 5:14 pm

Hmm, I did some fiddling with a ballistics program awhile back re a 45. The numbers I got suggested a common zero with a red dot, assuming it was mounted conveniently high. 'Conveniently', as in using 'normal' height rings and bases with a 30mm sight. Pushing it all as low as possible was counter productive.

It's going up at 25, and coming back down (maybe) at 50.

Some of the inspration for this was from reading a post on a machinist forum by ... Froneck ... ;-) IIRC, He had talked to one of the big time pistol smiths at Perry some years back, who said if you mount the sight high enough the zero is the same. Fred Kart comes to mind, but I might be mis-membering.

I also ran numbers for iron sights. Assuming a 'perfect' 6:00 hold, the relative sizes of the bulls, and the distances, the MOA worked out to zero-zero for 25 and 50. I thought that was way too convenient.

None of this accounts for gun movement while the bullet is in the bore, of course. If there's any effect at all. I'd think there should be, but ...

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