Home Forums Hunting & Shooting Muzzleloaders Effect of elevation on trajectory

Just got back from ML hunt. After 2 1/2 days of hard hunting, finally found some elk to hunt and got a 133 yard shot and totally wiffed. Got back to camp and took some sighting shots and was shooting 15-20 inches higher than back home. Elevation difference was approximately 5000 ft. and temperature at home 60 degrees +- and temperature on hunt in the teens.

Anyone with experience like this? Advice?

Change in air density over that range if elevation won't cause that much movement in POI. Don't know what load you're shooting but typically lower temp means lower velocity. Warp in the stock might do this, or perhaps your sight adjustment changed. We likely need some specific information about your gun/sight/load.

A 15 to 20 inch change in POI sounds lotsa screwy.

Take it out and shoot it at the home range and see if the POI once again changes.

The results will provide some insight.

What powder? What sights? I live at 7600 ft, hunt at 10,000 and have never seen a difference. I doubt at 133 yards, one would not se any difference in any firearm due to elevation change. Humidity in powder , cold would most likely make it shoot lower. Sight getting changed during travel or a carrying would be my suspicion.

It depends... if you were shooting up hill or down hill, you probably OVER-estimated the distance and "held" for the distance you estimated... a common mistake for a "flat-lander".

When shooting up-hill or down-hill, try to estimate the HORIZONTAL distance from you to the game you're shooting at and "hold" your sights according to that distance rather than to the distance it appears the game animal (elk) to be due to the up or down hill shot which always makes the shot seem further than it actually is.

I did some hunting in Colorado, west of Loveland Pass... up north around Rifle, Colorado and down south around Gunnison, Colorado in the Gunnison Mountains... and I can guarantee you a "flat-lander" like me needed to realize it's the horizontal distance you must "figure"... not what appears to be the distance to the animal that's up or down hill from your position.

When you checked your rifle's "zero" back at camp... was the target's elevation considerably higher or lower than your shooting position? If so, there's your "answer". If not... then it could be that your rifle's sights got "bumped" hard during your travels and they got "moved".

Other than those two "guesses"... I don't have any explanation for ya due to the elevation at which you were shooting. Certainly, the slightly thinner air wouldn't make THAT much difference in the point-of-impact.

Sorry you missed your elk... but "sh**" happens.


Strength & Honor...

Ron T.

I sight in at 7500ft, and hunt at 11,000-12,000ft, and don't see a difference in POI. At least not enough difference to worry about.

Elk have a big kill zone.

Thanks guys. Appreciate the input.

Shooting 110gr of 777 ffg with 370 gr Maxi Ball and musket caps out of western legal Traditions Vortek 30 inch barrel.

Shot was made with negligible elevation change and ranged with ARC compensating range finder to verify. Sighting was done on level ground as well.

Was the 777 a new container or was it last years that was opened? It does degrade after opening and causes some really weird groups.
Also, that is a heavy charge for a maxi ball. Usually best accuracy is about 90 gr.

If it is anew container of powder, I'd try 90 gr and then 100 if you can't find a reason fro the shift of POI.

Agreed. My brother shoots muzzell loader competitions and does quite well. He chuckles at how much powder people try to be accurate with.

Another person told me anything over 100 grains will not burn in the barrel but fly out the tube.

I am no means a muzzel fanatic....I hunt with the #@%^&$ thing because I have to. If I was a better bowhunter, or luckier at drawing rifle tags, I would sell mine. LOL

That is a fairly heavy load of T7 for that projectile. At the very least i would imagine the soft bullet may be leading the barrel.

I pretty much never exceed 80gr when shooting conicals and or never exceeding 1400ish fps.

Another old myth that isn't true. It might not all burn depending on the barrel length, and powder, but a lot of it will burn, and a chrono will prove that.

Whoa I am not a muzzel.....guy. Happy, Happy, Happy.

I believe what he is saying is that if that statement were true, the velocity of the bullet would not keep rising above 100 gr.

However, lets start at the beginning. There are lots of different powders. Black powder, pyrodex, 777, BH 209, etc. Some of these powders are more powerful than others and some of those burn faster/slower than others.

Second, how long is your barrel (22", 28, longer)? That affects powder burn.

In my experience, the powders burn pretty consistently for a given load. In other words, your crony will show consistent velocities up to powder amounts considerably greater than 100 gr, and they will keep rising with the increasing amt of powder.

I don't use powder above 100 gr for several reasons, none of which is incomplete powder burn. First and formost is I use big lead conicals, and I get the best accuracy with lower powder. Secondly, I am recoil shy and above 100 gr of powder, I start flinching. I also only shoot open sights, so long range is not an option for me. And lastly, powder is expensive, and when I can comfortably shoot an elk with 90-100 gr of powder, why would I want to spend/use more). I currently use 95 gr of 777 for elk and that is more than adequate.

However, some people say they get their best accuracy and trajectory with 120-130 gr of powder with sabots.

OK guys, thanks for the additional info. To clarify, my barrel is 30 inches.

On another thread before my hunt, I was working on getting my elevation sighted correctly. Withthe max adjustment using the factory sights I had to go to 110 gr of powder just to get it to zero (actually 2.5 inches low) at 100 yards. I did shoot a .75 MOA 3 shot group at 100 yards at my home elevation of 2800 ft.

My powder keg is new.

My loading/cleaning at the range and on the hunt were identical other than on the range I shot immediately an on the hunt I unloaded/shot gun at night, cleaned it, then ran another dry patch in the morning a loaded before the hunt.

Only other factor that was different I can think of was elevation and temperature.

Only idea thrown out that make sense is the sight was bumped off line, but I checked it again and it seems to remain tightly set and intact. I do plan to change sights out before a future hunt, but remain concerned about the results on the mtn.

Thanks again for the responses, I will look forward to any further input.

Have you shot the gun since being back to see if they POI went back down/changed? You need to.

+1

Check the flash channel, could be partially plugged.

Also check the sights.

I have never had conicals shoot well with a clean barrel. I did not read if you fouled the barrel or not. I have used hornady buffalo's, T/C maxi balls, and no excuses. 80-90grains triple 7 ffg or fffg. #11 cci or remington caps. FOULED the barrel...and even shot a few before I expected my T/C northwest explorer to behave.
My 209 primer T/C Omega (it has a faster twist) will shoot blackhorn powder and the Hornady jacketed non saboted projectiles with a clean barrel....but that is an illegal set up for Idaho.

Don't know if you can use the new Federal ML Projectile over there in Idaho, but we did get available in Colorado after submitting it. http://www.federalpremium.com/products/muzzle_loading.aspx