How high at 50 yards to be dead-on at 100 yards with this Blackpowder setup.

[Aim1]

I have a Thompson Center Encore Pro XT .50 cal with a 28" barrel. I'm shooting 270 grain Federal Copper BOR Lock bullets (in the below pic) with 100 grains (by volume which I think is 70 grains by weight) of Blackhorn 209 powder.

I only have access to a 50 yard range.

Sight line over the bore (top of the barrel) appears to be 1-1/8" inches. I'm using Warne medium height rings.


How high do I need to sight my rifle in at at 50 yards to hit dead-on at 100 yards?

 

[Loyalist Dave]

I only have access to a 50 yard range.

I think you're going to need a chronograph and the ballistic coefficient of those projectiles to get a proper answer.

LD

 

[Bill M.]

For sure we will need to know the height of your site line over the bore.

 

[Aim1]

For sure we will need to know the height of your site line over the bore.

From the top of the barrel appears to be 1-1/8" inches.

 

[J-Bar]

Here is a SWAG based on the following parameters:

BC of a 50 caliber 270 grain projectile is going to be in the ballpark of 0.25 (I looked at the ballistic coefficients of similar projectiles and made a guess.)
Your muzzle velocity is going to be around 1350 fps give or take of course. (perused online muzzleloader ballistic tables and made a guess).
Sights 1.12" above bore.

According to one of those online calculators, at 100 yards a bullet with those parameters is going to drop about 5" below a 50 yard zero. So if you make it hit 5" high at 50 yards, the point of impact at 100 yards should at least be on paper.

But I absolutely would not take a shot at an animal until I had confirmed the point of impact with an actual 100 yard shot.

 

[Loyalist Dave]

According to one of those online calculators, at 100 yards a bullet with those parameters is going to drop about 5" below a 50 yard zero. So if you make it hit 5" high at 50 yards, the point of impact at 100 yards should at least be on paper.

But I absolutely would not take a shot at an animal until I had confirmed the point of impact with an actual 100 yard shot .

Agreed

So IF, and as J-Bar noted, this is an IF....

The older way one would sight in the rifle would not be 5" high at fifty.

Because you don't want to be having to guess at a low aim at 40 to 60 yards. You'd want 3" high at fifty yards which would give you 2" low at 100. Because 5" at 50, may give you poor placement at that distance, and you can't ensure your shots will always be from 70-100 yards.

In this illustration, you don't have the lower edge of the deer to use as an aiming point which you might really need to put that round into the lungs at 50 yards when you are hitting 5" at that distance..

The green dot is the aiming point.
IF you're sighted in 5" high at fifty then at 50 yards you get a high lung shot, and if you're firing down hill a bit, you get a slightly higher hit, top edge of the lungs or between lungs and spine. Either of these will often produce a poor track and a long track as the chest cavity holds a lot of the blood. IF you try the shoulder shot at 50 with the impact 5" above, you may get a spine hit, or you may miss, especially if you are shooting a bit down hill.. (red circles)

IF zero 3" high at fifty yards, you can see that if the aim point is the green circle, you hit the upper black circle, still a good lung shot at 50 yards, and out to 100 the impact is 2" low, so it's a heart/lung shot. At ranges between 50-100 the impact is someplace between the two black circles...all good hits.

If you shoot a shoulder shot using the green dot as where you sight in on the deer's body, if you're 5" high... then you may hit the spine, but slightly down hill you might even miss (red circles). If you're sighted 3" high at fifty... then you'd hit the upper black circle. From 50-100 yards using a 3" high sight-in at 50... the bullet hits somewhere between the upper and lower black circles on the shoulder shot. These would be good too.



LD

 

[wasa]

I've done a bit of research into the BOR-Lock. BC=0.168. Random internet person has 2 x 50gr pellets of Triple Se7en at 1794 fps from a CVA Accura (25" barrel). I believe BH209 is "more powerful" than T7. Going to Hornady's website and using their calculator they estimate 1.1 inches high at 50 yards.

The big factor here is your muzzle velocity. I personally think 1350 ft/s is low, but as others said, you need a chronograph (or figure out what others have measured). Barrel length is important. Random people say anywhere from 10 fps to 50 fps per inch.

If velocity is 1500 fps then you need to be 2" high at 50 yards.

https://www.hornady.com/team-hornady/ballistic-calculators/#!/ and play around with the numbers.