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Old December 23, 2018, 03:11 PM   #1
Safaripolice
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100 yard 0 and -2.5” at 10 yards?

Hey guys and gals quick question

My 25-06 rifles are both zeroed at 100 yards one with 100 grain and the other with 117 grain.
100 sp is around 3200 FPS
117 sst is around 3000 FPS
I was doing some messing around with close targets yesterday and noticed I was shooting low approximately 2-2.5” at around 10 yards. Does that sound correct. I thought most of my shots would be at 100 or over but so far they have been closer then 75 yards and I have passed on deer at around 25 yards as I was tagged out on does and looking for a buck.

Just want to know where to aim if I get a close shot under 25 yards

Thanks
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Old December 23, 2018, 03:48 PM   #2
HiBC
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Draw a picture. Draw one straight line to represent the line your sights work with.Your scope is above the bore centerline a distance,perhaps 2 in.That varies with ring height. That line is straight.

Now you need to consider another line. The axis of the bore.Its straight,too.You scope knobs let you adjust the axis of the line of sight.We adjust the axis of the line of sight and the axis of the bore so they cross at a fairly close range.This range will vary with sight height and the desired sight in distance. Typically,it might be 25 to 40 yds,just to give you an idea

The bullet exits the bore following the axis of the bore. There is a fine point to grasp here.As soon as the bullet leaves the bore,gravity begins to accelerate it towards earth at an acceleration of approx. 16 fps per second ,assuming horizontal flight.

Technically,the bullet never "rises" But the upslope of the bore axis tosses the bullet up through the line of sight,and they cross twice.Once at the approx. 25 to 40 yd place,then for a while the bullet is above the line of sight. This is described as "mid range trajectory" You will see that term again. The bullet reaches a max midrange trajectory,then gravity begins to pull it down. The bullet crosses the line of sight again.That is your sighted in range. Beyond that,the bullet path will be below the line of sight as it accelerates toward earth.

With your high vel cartridge,try a 40 or 50 yd target. If you are sighted in at 100 yds,there will be an intermediate range where you are dead on.


Remember that range.It will be useful for future sight ins


I don't know what part of a deer you aim at, but I think you might not be looking at the correct reason you missed.


Actually measure your sight height.Like,1/2 the scope tube dia,plus 1/2 the receiver dia,plus the space between the receiver and the scope tube(or another method)


For a low mounted hunting scope,thats often 1 1/2 in.If you have a high mounted scope,it will be a bit more.


That distance is the MAX you could have "missed" Even if that's 2 in,you must be shooting at the edge of the deer.


But,at someplace betwee 25 and 40 yds,or thereabouts,the line of site vs line of bore would be very close. I doubt you had even 1 inch of error per your theory.Should be eating venison.


Do more checking to verify,but I strongly suspect you missed for another cause.

Last edited by HiBC; December 23, 2018 at 04:03 PM.
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Old December 23, 2018, 03:55 PM   #3
Safaripolice
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Thank you. It makes sense. I always knew the bullet could not rise unless it had a rocket attached to it lol and an elevator like my Cessna. But I’m trying to really nail down the trajectory and physics behind it. I have several trajectory apps including the Nikon one for my BDC scope but I was always wondering about those close 10-30 yard shots which apparently I can’t get with my bow but with my rifle I have passed on 2-3 does this year less then 30-40 yards away. Strange how that works.
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Old December 23, 2018, 05:03 PM   #4
HiBC
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Put it on the lungs and pull the trigger. Odds are you will hit closer than you would with the arrow. I don't think the deer will notice an inch or two.
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Old December 23, 2018, 05:47 PM   #5
jmr40
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Quote:
Technically,the bullet never "rises"
Yes, it does.


If your barrel were parallel to the ground the bullet would begin to drop as soon as it exits the muzzle. But since the scope, or iron sights are mounted ABOVE the barrel the muzzle will always be elevated slightly when looking through the sights and the bullet will always travel in an arc.

The bullet will start out about 2" lower than the sights and must travel upward for some distance before the bullets path intersects with the sights on the rifle, or handgun for that matter. All bullets have 2 zero's, one on the way up, and a second on the way down. At very close range the bullet will be hitting lower than where the sights are pointing. As it moves up it will coincide with the sights. This 1st zero is where most handguns are regulated. If zeroed at 15 yards it isn't uncommon for them to hit a little high at 25, then a little low at 50.

Rifles are normally regulated at the 2nd zero. Your 25-06 should be a little low up close and will probably be zeroed for the 1st time at about 50-75 yards. It is again zeroed at 100 and then drops below the sights at longer ranges.
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Old December 23, 2018, 06:04 PM   #6
HiBC
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[QUOTETechnically,the bullet never "rises" But the upslope of the bore axis tosses the bullet up through the line of sight,and they cross twice.Once at the approx. 25 to 40 yd place,then for a while the bullet is above the line of sight. This is described as "mid range trajectory" You will see that term again. The bullet reaches a max midrange trajectory,then gravity begins to pull it down. The bullet crosses the line of sight again.That is your sighted in range. Beyond that,the bullet path will be below the line of sight as it accelerates toward earth.][/QUOTE]


There is what I wrote.You might read it again. I think semantics arguments are an annoying waste of time. I stand by "The bullet does not rise" above the line of the bore. If I had said "The bullet rises" I would have had critics,too.And they would have been correct.


1) The context of my explaination explains the "upslope of the bore tosses the bullet up through the line of sight....etc" What humanly possible more do you want?


2) We agree. Your argument restated ,in different words,exactly what I explained.
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Old December 23, 2018, 06:08 PM   #7
Sharkbite
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The bullet never rises above the bore line.
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Old December 23, 2018, 06:29 PM   #8
Safaripolice
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Quote:
Originally Posted by HiBC View Post
Draw a picture. Draw one straight line to represent the line your sights work with.Your scope is above the bore centerline a distance,perhaps 2 in.That varies with ring height. That line is straight.

Now you need to consider another line. The axis of the bore.Its straight,too.You scope knobs let you adjust the axis of the line of sight.We adjust the axis of the line of sight and the axis of the bore so they cross at a fairly close range.This range will vary with sight height and the desired sight in distance. Typically,it might be 25 to 40 yds,just to give you an idea

The bullet exits the bore following the axis of the bore. There is a fine point to grasp here.As soon as the bullet leaves the bore,gravity begins to accelerate it towards earth at an acceleration of approx. 16 fps per second ,assuming horizontal flight.

Technically,the bullet never "rises" But the upslope of the bore axis tosses the bullet up through the line of sight,and they cross twice.Once at the approx. 25 to 40 yd place,then for a while the bullet is above the line of sight. This is described as "mid range trajectory" You will see that term again. The bullet reaches a max midrange trajectory,then gravity begins to pull it down. The bullet crosses the line of sight again.That is your sighted in range. Beyond that,the bullet path will be below the line of sight as it accelerates toward earth.

With your high vel cartridge,try a 40 or 50 yd target. If you are sighted in at 100 yds,there will be an intermediate range where you are dead on.


Remember that range.It will be useful for future sight ins


I don't know what part of a deer you aim at, but I think you might not be looking at the correct reason you missed.


Actually measure your sight height.Like,1/2 the scope tube dia,plus 1/2 the receiver dia,plus the space between the receiver and the scope tube(or another method)


For a low mounted hunting scope,thats often 1 1/2 in.If you have a high mounted scope,it will be a bit more.


That distance is the MAX you could have "missed" Even if that's 2 in,you must be shooting at the edge of the deer.


But,at someplace betwee 25 and 40 yds,or thereabouts,the line of site vs line of bore would be very close. I doubt you had even 1 inch of error per your theory.Should be eating venison.


Do more checking to verify,but I strongly suspect you missed for another cause.
It wasn’t a miss. I just passed on a few does as I’m tagged out already. I’m looking for a buck before season ends. So far haven’t missed this season just wanted to finesse the trajectory. But I think I got a better understanding now. Thanks to all.
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