6.5 PRC Ballistics - drops don’t match ballistics chart

John Spadaro

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Nice setup!

Now that you have the scope adjustment figured out that makes hitting at long range much easier. I was playing with my isnipe app and can’t quite line up with your measured drops, but I can get close.

I used 3120fps, g7bc of 3.18 and I used an average pressure that I would see here (I live at 3100’).
At 300 yards I have 3/4” more drop, at 500 1” more drop at 600 I have 3” more drop. The 400 I can’t seem to get close I am always roughly 4” more drop no matter what I change I can’t close the gap.

When you look at what group sizes would be using your 1/2moa groups the 300/500/600 actually line up fairly well. The 400 would be an outlier. To get closer calcs I would need you scope height and actual air pressure.

With your actual measured drops, and knowing what your scope actually adjusts you should be able to make hits out to 600. I would try and do some paper shooting before game but you are fairly close.


If it helps my scope height is 1.77”. Thanks for taking the time to run the calculations. Based on my recent test of colder cartridges I think my actual MV is going to be significantly less than 3100.

Based I what I know right now I am going to limit my hunting to 400y. Maybe when I have more experience in testing at longer distances I can increase my comfortable range.
 

User4302021

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Why would you zero at 100 yards when your desired target is an elk? I’d be 3” high at 100 and I’d have a shot where I could hold dead on to 400 yards, given the kill zone for an elk.

Secondly, I wouldn’t shoot an elk with a 143 grain bullet at over 100 yards anyway.
Some of us are using something other than a Leupold 3x9, and can actually zero at 100 Yards and then dial whatever exact adjustment we need in a few seconds.

If we want a 200 or 300 yard zero for particular situation, it is a simple twist of the turret.
 

Daddyneuf

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First of all how many elk have you killed?
Second Deer and Elk are open at the same time here in Montana some units close mule deer Nov.15th. So I guess your good with a 9" drop at 400 on a deer being 3" high at 100
I said nothing about a deer

I said kill zone on an elk and I still stand by never sighting in a hunting rifle at 100 yards.
 

Daddyneuf

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Some of us are using something other than a Leupold 3x9, and can actually zero at 100 Yards and then dial whatever exact adjustment we need in a few seconds.

ok, if you remember to adjust the turret

I think adjusting the elevation for a 300 yard shot on an elk is grossly over-complicating the shot

If we want a 200 or 300 yard zero for particular situation, it is a simple twist of the turret.
 

User4302021

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I said nothing about a deer

I said kill zone on an elk and I still stand by never sighting in a hunting rifle at 100 yards.
Why?

Why limit ourselves to relying on the old maximum point blank range concept when we can have both?

As I said before, we are using scopes meant to be dialed. What is the disadvantage of 100 yards being called "zero" rather than 200 yards? With a twist of a turret we can have any zero we want.

The purpose of a 100 yard zero is that all adjustments are "up" from "zero". You will never need to dial down for anything.
 

User4302021

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It is no harder to use the reticle to hold over for a 300 yard shot with a 100 yard zero than a 200. This is longrange hunting, we aren't saddled with duplex reticles and capped turrets. This is what we train for.

It isn't 1980 anymore.

...or maybe you thought you were on Shortrangehunting.com?
 
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Daddyneuf

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It is no harder to use the reticle to hold over for a 300 yard shot with a 100 yard zero than a 200. This is longrange hunting, we aren't saddled with duplex reticles and capped turrets. This is what we train for.

It isn't 1980 anymore.

...or maybe you thought you were on Shortrangehunting.com?
You’re missing the point, at 200 or 300 yards I’m not “holding over”

I’ve killed more groundhogs at 400 yards than you’ve killed elk at that range.

And I never touched the elevation on my scope

but you do it your way
 

User4302021

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You’re missing the point, at 200 or 300 yards I’m not “holding over”

I’ve killed more groundhogs at 400 yards than you’ve killed elk at that range.

And I never touched the elevation on my scope

but you do it your way
Actually, I am extremely well aquainted with the concept of danger space (maximum point blank range). It is exactly the same concept behind a 300 yard battle sight zero.

It was always meant to give the lowest common denominator a reasonable chance of success.

As far as groundhogs go, I doubt you remember how many you've missed as well.

Since you don't know me, you have no idea what I've killed...but as far as elk sized creatures, my longest kill was right at 700 yards in a 15 mph full value wind. The vital zone was over 24" wide...but I hit him in the heart.
 

L.Sherm

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Most folks cite it at an 18” diameter. Some go bigger

so it’s almost beach ball size
So at 9" your at the very bottom of the kill zone if its 18"with zero human error which happens alot in hunting situations.
 

L.Sherm

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Back to my other 2 questions how many elk you taken?
What about a deer, there open at the same time in montana were the O.P was planning on hunting elk.
 

Daddyneuf

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Back to my other 2 questions how many elk you taken?
What about a deer, there open at the same time in montana were the O.P was planning on hunting elk.
Look, I’m sure you’re a nice guy

I’m not looking for an argument, I just can’t imagine the reasoning for the original post

BTW, a 6.5mm isn’t a legal caliber in Kentucky for elk
 
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