Thread: Long Range Shooting and TBR

Originally Posted by Gibo

Its got me bamboozled

Found this quote

"Rifleman's rule has another nice property besides simplicity: it does not depend on the rifle, caliber, zero distance, etc. - just inclination and distance. This allows implementing it in universal laser rangefinders.

Sadly it is based on the assumption that bullet travels in vacuum and its use on Earth has significant limitation.

Originally Posted by Gibo

Its got me bamboozled

Greeting Gibo,
Me too. In my minds eye I can see all this going on while the deer wanders out of sight and very likely dies of old age.
Regards Grandpamac.

Originally Posted by grandpamac

Greeting Gibo,
Me too. In my minds eye I can see all this going on while the deer wanders out of sight and very likely dies of old age.
Regards Grandpamac.

Mate in all honesty you’d be surprised at how quick and prepared you have to be especially with Sika. Often you may get two or three minutes if that.
I’m no stranger to bush hunting but to me there is nothing better than sitting back and watching how animals actually behave in their environment. It’s amazing what I’ve actually learnt about deer.

650y (line of site) @ 20° angle = 68" of drop

611y (TBR) @ 0° angle = 62.5" of drop

Error in mm's = 140

This is now getting into 'missing deer territory' taking other field shooting factors into consideration as well.

Both the examples you have above show an error of less than 1 MOA.

It just illustrates the problem with ethical hunting at extended ranges...

Let's be honest, most guys with their hunting rigs struggle to hit a 2 MOA plate beyond 400 yds

A solid kill zone on a deer to me is about a 300mm diameter circle. Then work it backwards, if you can truthfully hit a 2.5 MOA sized target repeatedly and consistently (under stress and time pressure), then the max distance you should really be looking at hunting is around 450yds.

Originally Posted by ebf

Both the examples you have above show an error of less than 1 MOA.

It just illustrates the problem with ethical hunting at extended ranges...

Let's be honest, most guys with their hunting rigs struggle to hit a 2 MOA plate beyond 400 yds

A solid kill zone on a deer to me is about a 300mm diameter circle. Then work it backwards, if you can truthfully hit a 2.5 MOA sized target repeatedly and consistently (under stress and time pressure), then the max distance you should really be looking at hunting is around 450yds.

In fairness that’s probably for another post.

My guess is that those that are relying solely on their rangefinders TBR outputs to calculate an inclined shot aren’t shooting as steep or as far as they think they are.

Originally Posted by ebf

Both the examples you have above show an error of less than 1 MOA.

It just illustrates the problem with ethical hunting at extended ranges...

Let's be honest, most guys with their hunting rigs struggle to hit a 2 MOA plate beyond 400 yds

A solid kill zone on a deer to me is about a 300mm diameter circle. Then work it backwards, if you can truthfully hit a 2.5 MOA sized target repeatedly and consistently (under stress and time pressure), then the max distance you should really be looking at hunting is around 450yds.

300mm may be ok for big reds but on small fallow the lethal zone reduces to half that and it gets pretty tricky over 200m.

Il stay under 400yds,still gota go and pick up the deer.Good luck with yr findings Tui4Me.

To be fair that if you don't under stand whats been talked about you shouldn't be shooting past 450m at the most.
I would go as far to say there is a hell of a lot of people taking shots at animals and can't work out why they are missing or fluke a good shot every now and again.
Yes I do know what I am talking about.

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Originally Posted by andyanimal31

To be fair that if you don't under stand whats been talked about you shouldn't be shooting past 450m at the most.
I would go as far to say there is a hell of a lot of people taking shots at animals and can't work out why they are missing or fluke a good shot every now and again.
Yes I do know what I am talking about.

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See quite a bit of that on youtube. Long range. Clean misses.

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Greetings All,
So to summarise, the use of true ballistic range to calculate drop allows for all of the drop due to gravity and most of the drop due to velocity loss What it does not allow for is the additional velocity loss due to the difference between TBR and line of sight range (the actual distance to the animal). This becomes significant as inclination and range increase and as ballistic coefficient decreases. The consensus also seems to be that this becomes important somewhere beyond 400 metres. From Tui4Me,s example above the error is around 0.5 MoA at 650yards (600 metres). Hard to hold that close in field conditions. Significant as this may be it seems small potatoes compared to allowing for wind deflection at these ranges. Something to think about.
Regards Grandpamac.

Spent this past weekend participating in a extra long range event on a central north island station.

After speaking to several of the other competitors, and doing some testing, I am starting to think @Tui4Me is onto something here.

I was also not correct in saying the flight time (in the software) for the 2 scenarios would be similar.

Taking the 1000m / 20 degree angle

940 @ 0 : 1.522 sec
1000 @ 20 : 1.622 sec

this is for something leaving the muzzle at 875 m/s, so it does make sense.

The actual flight time will be the longer value, gravity only works on the short leg of the triangle. Because the solver is time-of-flight based, you will get a more accurate value by entering the true LOS value and angle, as opposed to just the TBR value.

Lets put this to bed guys..

1. "First, the range scaling ignores the effect of the bullet slowing down as it travels thru all the air between the shooter and the target." - Bryan Litz

2. Second, range scaling ignores the effect of the gravity that's either acting to decrease or maintain the bullets speed." - Bryan Litz

3. In addition range scaling does not distinguish between uphill and downhill shooting" - Bryan Litz.

@Tui4Me, where are those Litz quotes from pls.

Interested to read more about his comments of differences between uphill/downhill.

Originally Posted by ebf

@Tui4Me, where are those Litz quotes from pls.

Interested to read more about his comments of differences between uphill/downhill.

At a guess shooting downhill the bullet stays faster for longer. Uphill slows down quicker due to gravity. The longer or shorter its flying will move it further along its curve (or not)

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