Monday, January 20, 2014
"Why Can't I Duplicate The Load Ballistics Published On The NORTH AMERICAN MUZZLELOADER HUNTING Website?"
World events are so much easier captured for the public to see due to the fact that such a large percentage of people now have a camera with them at most times - whether that camera is an actual digital still or video camera...or simply a cellphone with photography or video capability. Snapping photos, either still or moving, has never been easier.
Somewhat in the same light, inexpensive yet reliable chronographs have made it so much easier for the typical shooter to clock the bullet speeds of his loads. On a somewhat regular basis, NORTH AMERICAN MUZZLELOADER HUNTING hears from muzzleloading shooters who have acquired a new chronograph - and a few have been shocked to find that, shooting the same rifle...powder...charge...sabot...and bullet...ignited by the same No. 209 primer or percussion cap...they are getting velocities that are often 50...75...or even 100 f.p.s. different than the loads and data we've compiled on all of the pages found at the following link -
That does not surprise me. The fact is, on any given day, I experience the very same thing. It simply boils down to the fact that you are not going to get the same velocities on a -10 degree (F) morning that you achieve on a +80 degree (F) or warmer afternoon. Likewise, a variety of other factors also come into play that will affect the day to day velocities any shooter achieves, including the percentage of relative humidity in the air and the elevation of the range where you are shooting.
I've been on hunts where mornings were below zero and afternoons well into the 50's. Yes, it will affect point of impact...but normally not enough to be of any real consequence. A 50 or 60 degree temperature change will very commonly move point of impact up or down an inch or two - but with a properly sighted modern in-line rifle and a good center hold on the chest cavity of the game being hunted (at 50 to 150 yards), shooting a 250- to 300-grain saboted spire point bullet at 1,900 to 2,000 f.p.s., should put the shot squarely through the kill zone, perhaps an inch higher or lower than where the crosshairs were at the shot.
Here at NORTH AMERICAN MUZZLELOADER HUNTING, we try to hit our range two or three times a week in April, May and June, then again in late September, October and early November - basing when we shoot on temperature. Our range (shown above) is located in a shallow valley about 15 miles northwest of Missoula, MT. For us, the ideal shooting temperatures are 45- to 55-degrees - often meaning that during early Spring and late Fall, we shoot more in the afternoons - while in late Spring and early Fall we hit the range in the mornings.
The ballistics data on the website was compiled from the shooting we've mostly done within that temperature range. Still, we do a great deal of shooting when it's much hotter...or much colder. This ongoing testing is conducted to see how those weather changes affect velocities, accuracy and point of impact. Our published loads and data are simply a base, shooting during the most ideal weather and temperature range, in order to allow a comparison of rifle, powder and projectile performance.
During 2013, between our coldest and hottest shooting sessions there was an extreme spread of almost 110-degrees (-10 the coldest and +99 for the hottest). Shooting our 30-inch barreled Traditions .50 VORTEK Ultra Light LDR test rifle, loading with 110-grains of Blackhorn 209 and the 300-grain Scorpion PT Gold, we experienced right at a 90 f.p.s. variation in velocity (fastest during cold weather and slowest during extremely hot weather). Still, every shot would have taken a whitetail at 100 yards.
Before heading out on a 2013 Missouri Breaks hunt the week before Thanksgiving, the sighting of the rifle was tweaked to bring the point of impact up about an inch - and 5 days later a single shot dropped a nice 10-point buck at 140 yards. As the weather changes, tweaking the sighting of any modern in-line rifle should be an ongoing thing...especially when a major weather and temperature change rolls in. - Toby Bridges, NORTH AMERICAN MUZZLELOADER HUNTING
Here's A 2011 Article/Report That Takes A Look At "Variables In Muzzleloader Ballistics & Performance" -