Thursday, June 12, 2014

Do Radical Changes In Elevation Cause Radical Changes In Point Of Impact?


My personal shooting range is located on what was once the bottom of an ancient lake that was in some places 2,000-feet deep.  Of course, that was more than a million years ago, and the bottom of that huge glacier created lake is now the Missoula Valley of Western Montana.  The elevation where I annually shoot 3,000+ muzzle-loaded rounds is right at 3,000 feet.

Missoula, a city of 70,000 people, is the largest such city in the U.S. that is completely surrounded on all sides by mountains...with some of the peaks reaching 9,000 feet.  There is easy access to a lot of high country where, when it begins to heat up too much in the valley bottoms to do a lot of shooting with saboted bullets, that I can load up and drive to a reasonably remote mountain valley or ridge and get in a morning of shooting with temperatures in the 40's - even in July and August.

On my valley range, I generally sight rifles to place point of bullet impact approximately 2 inches high, to preserve my point of aim.  When we take the dogs and spend a few days in the mountains to get away from city noises, I always take along a muzzleloader or two - and try to get is some high elevation shooting.  I have noticed that at 5,000 to 6,000 feet, point of impact often moves up another inch or two - depending on the load and bullet.

One test I hope to complete by the end of summer is to see if I can actually discern an approximate change in that point of impact at 4,000...5,000...6,000...and maybe 7,000 feet.  The rifle I'll be using for this test is the new 30-inch barreled Traditions .50 VORTEK StrikerFire LDR - shown in the photo above.  This shot was taken at one of my favorite high country shooting spots, at about 6,000 feet.  The snow capped mountains in the background are the Mission Mountains of Western Montana...with several peaks up around 9,000+ feet. 

If you have the opportunity to shoot at such radical changes of elevation...have you noticed any significant changes in point of impact?

This will be posted as the July "Question of the Month" on the NORTH AMERICAN MUZZLELOADER HUNTING website - at www.namlhunt.com

Toby Bridges
NORTH AMERICAN
MUZZLELOADER HUNTING 


If you have any insight on this topic, please drop us an e-mail at - namlhunt@gmail.com 

1 comment:

  1. Toby, I'll chime in here as I have shot at extreme variations in elevation. Full disclaimer, not with a ML. However, I'll share my thoughts anyway just in case they are of any use to the data you are compiling. I lived in Colorado for several years & often sighted my rifle in down on the plains which are about a mile or so above sea level. When I shot them in the high country, as high as a hair over 13,000ft I noticed that my bullet dropped much less. I assume due to lower friction of thinner air. Let me assure you that thin air is hard on a fat kid! A friend brought out a long range tactical rig which he had done extensive shooting with back in West Virginia. He had plotted out the drop of his load out to obscene ranges. Having shot the rifle back there I knew what it could do & knew his "dope" was spot on. That rifle was zeroed there at 1800ft elevation & we took it up above tree line into the tundra to see what it could do. Tree line there is near 12,000ft. All of his "dope" was significantly off as far as how much elevation needed to be "dialed" in. I figured it would be off but not that much. Anyways, hope this helps & I apologize for it not being about muzzle loaders.

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