Thread: Long Range Shooting and TBR

Originally Posted by Gibo

How can it be faster to input 1 distance (TBR) than a distance and angle? Makes no sense, or are you implying after 400m TBR rangefinders are inaccurate?

IMO - Based on the drops I have calculated comparing them, and the article Chalkeye posted about TBR, I wouldn't recommend shooting at a deer using TBR past 400m.

TBR is great for someone with a ballistic reticle that wants to shoot out to 400m but beyond that it has limitations.

@Tui4Me, I think you meant to say BDC in post 14. Up to 400 BDC is good.

Beyond that you can either enter the line-of-sight distance and an angle, or simply the TBR / EHR value on it's own (it is already corrected for angle).

@Pommy, most ballistic solvers are time of flight based. Time of flight is pretty much identical whether you fire a shot at 0 degrees, 45 degrees, or straight down a vertical mine-shaft. But there is a significant difference in the amount of elevation you would need for each of those 3 shots. When I teach people about incline shooting, I've found it often takes them thinking about firing a shot straight down before they really start understanding the concept.

That makes more sense

Originally Posted by ebf

@Tui4Me, I think you meant to say BDC in post 14. Up to 400 BDC is good.

Beyond that you can either enter the line-of-sight distance and an angle, or simply the TBR / EHR value on it's own (it is already corrected for angle).

@Pommy, most ballistic solvers are time of flight based. Time of flight is pretty much identical whether you fire a shot at 0 degrees, 45 degrees, or straight down a vertical mine-shaft. But there is a significant difference in the amount of elevation you would need for each of those 3 shots. When I teach people about incline shooting, I've found it often takes them thinking about firing a shot straight down before they really start understanding the concept.

When I did some ballistic calcs and compared bullet drops (in inches) using the line-of-sight distance/angle inputs against TBR/EHR on its own I found huge differences at longer ranges?

Is TBR not just a formula that takes the angle between you and the target to work out the horizontal distance?

It would need to know BC and velocity to approximate TOF. So if your rangefinder has profiles for different calibers or lets you input the variables, then it's perhaps doing something more clever. Different manufacturers use different acronyms too which is a little unhelpful.

A range finder TBR is basically applying this rule.

Originally Posted by Tui4Me

Attachment 168575

A range finder TBR is basically applying this rule.

Is there much issue if you get the angle wrong at long range? To me that would be quite easy to do? But I dont do it

Originally Posted by Gibo

Is there much issue if you get the angle wrong at long range? To me that would be quite easy to do? But I dont do it

At longer ranges, you certainly need to be measuring angle accurately and allowing for it if you want to take venison home.

Originally Posted by Tui4Me

At longer ranges, you certainly need to be measuring angle accurately and allowing for it if you want to take venison home.

So do you use a device to measure angle? I think some shooter apps you can point at the target and it does it. If that's the case why would the TBR function in a range finder be wrong?

Originally Posted by Gibo

So do you use a device to measure angle? I think some shooter apps you can point at the target and it does it. If that's the case why would the TBR function in a range finder be wrong?

I use a range finder that can display an angle.

I do totally agree with your last comment, but all that I can think of is that the ballistic app is obviously doing more behind the scenes than simply working out the true horizontal distance like a range finder does.

Its got me bamboozled

Can your rangy also do TBR
Be interesting to have a set target at set angle at a good distance and compare the two methods side by side.
Or get one that has it and see how they compare?

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

Can your rangy also do TBR
Be interesting to have a set target at set angle at a good distance and compare the two methods side by side.
Or get one that has it and see how they compare?

I agree with Gibo about doing a test.
I always use TBR on my range finder and have shot deer out to just short of 600 and hit where I aimed.

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@Tui4Me, I suspect you simply forgot to remove the angle value when you entered the TBR. Remember that when you use a TBR value, the angle needs to be reset to 0

TBR is just simple trigonometry. You effectively have the hypotenuse, and want to calculate the length of the adjacent side. The formula is:

adjacent = cos(angle) x hypotenuse

There is a small difference between entering just the TBR into a ballistic solver, compared to entering the line-of-sight range and the angle. But it should not be more than 1 or 2 clicks, assuming your turrets are 1/4 MOA or 1/10 MRAD.