High altitude hunting

[Zutt-man]

I’m planning on hunting high country mule deer with the old man this September. Looking at focusing our efforts at 11-12,000’ in Colorado. I don’t foresee us taking shots over 100 yards as neither of our eyes would allow it with our flinters. One thought (small concern, but I’m not sure it should be at our ranges) I have is trajectory being affected in that altitude. Our loads are developed at 1,000’ and there’s really not a good way of testing them without blowing out basins when we go. Should we have cause for concern within 75 yards?



Just for giggles, here are is my 5 shot 50 yard grouping with my Kibler .58 colonial. 80 gr FFF, .015 spit patch and hornady .57 rb.

 

[wiscoaster]

Trajectory will be flatter due to less aerodynamic drag, ie less drop over distance. 75 yards isn't that long of a range; I can't speak from experience, but I suspect for that load and caliber the difference in elevation offset due to altitude isn't enough to adversely affect your clean kill.

If you know what the muzzle velocity is for that load and what the ballistic coefficient is for your round ball, here's a ballistic calculator that goes to 15,000 feet:
https://www.hornady.com/team-hornady/ballistic-calculators/#!/
Neither of the drag coefficient models are applicable to round balls, but the G1 model is closer. The calculator won't be "correct" but might give you an idea of "how much".

I don't know what any of your numbers are for your setup, but just for grins I ran two calculations for 150 gr bullet at 1000 fps muzzle velocity and 0.5 ballistic coefficient using the G1 model at 1000 ft and at 10,000 ft. At a 100 yd scope or open sight zero, the 1000 ft trajectory was 3.1 in high at 75 yds and the 10,000 ft trajectory was 3 in high.

 

[Zutt-man]

Trajectory will be flatter due to less aerodynamic drag, ie less drop over distance. 75 yards isn't that long of a range; I can't speak from experience, but I suspect for that load and caliber the difference in elevation offset due to altitude isn't enough to adversely affect your clean kill.

If you know what the muzzle velocity is for that load and what the ballistic coefficient is for your round ball, here's a ballistic calculator that goes to 15,000 feet:
https://www.hornady.com/team-hornady/ballistic-calculators/#!/
Neither of the drag coefficient models are applicable to round balls, but the G1 model is closer. The calculator won't be "correct" but might give you an idea of "how much".

I don't know what any of your numbers are for your setup, but just for grins I ran two calculations for 150 gr bullet at 1000 fps muzzle velocity and 0.5 ballistic coefficient using the G1 model at 1000 ft and at 10,000 ft. At a 100 yd scope or open sight zero, the 1000 ft trajectory was 3.1 in high at 75 yds and the 10,000 ft trajectory was 3 in high.

Thanks for the link! Ran the numbers and there’s absolutely nothing to worry about at the distances we’re shooting.

 

[R Ellis]

We have checked our loads in Colorado before and their was no difference and we sighted in here at home at 800 feet

 

[Absoroka]

I would be more concerned about the performance of my lungs and legs with a 10,000 foot elevation change. Oxygen gets harder to come by at that elevation.

 

[JimCunn]

Have you spent much time at 10-12,000 feet?
It can be deadly.

 

[Duk]

When i was a bit younger i was doing a lot of back country backpacking at 10,000-12,000 feet i felt like i had half a jag on and always short on breath

 

[Zutt-man]

Both of us are well versed backpackers and both have spent some time at high altitudes

 

[Christophero]

Both of us are well versed backpackers and both have spent some time at high altitudes

That's a beautiful bull elk in your avatar with the muzzleloader next to it. Hope your next trip is as successful.

 

[zerosprk]

Aim for the ribs and let 'em have it. If you do your part, it will be the good kind of work after that.

 

[longcruise]

We have checked our loads in Colorado before and their was no difference and we sighted in here at home at 800 feet

I've checked it out and found the same. I think if you locked your gun in a vice and shot a group the shot to shot variance would probably be greater than the effect of altitude.

Good that you are ready for elevation. So many who come here are not.

 

[Zutt-man]

Circling back to this.

Dad ended up being successful! His first mule deer and black bear. We ended up filling 2 of our 3 tags!

 

[harleysboss]

Looks like you both had a Great Hunt! Congrats!!

 

[Stykbow]

Outstanding @Zutt-man! Congrats.

 

[Loyalist Dave]

One thought (small concern, but I’m not sure it should be at our ranges) I have is trajectory being affected in that altitude. Our loads are developed at 1,000’ and there’s really not a good way of testing them without blowing out basins when we go. Should we have cause for concern within 75 yards?

The thinner air will give you a bit flatter trajectory. IF you want the ball to arrive supersonic at 75 yards at 11,000 feet, you will need a load that starts at 1400 fps. You might want to chrono your load.

LD

 

[Buff1958]

too cool……. congrats