By The Numbers…


One of the unwritten rules in writing for gun magazines is “Few numbers, fewer graphs and never, ever formulae!” Obviously, most gun editors consider their readers to be slack jawed, mouth-breathing, grade school drop outs. After reading some of the gun rags, they may be right. All of our clever little Junior Technoids out there are bright as new pennies. Numbers are mother’s milk to us. Numbers are goodness personified. Why, numbers even add up! And down.

Youze wanna see sum numbahs? (as our cousin Bosko the CPA says):

Pellet energy: A #7 1/2- pellet starting out at a “light” load speed of 1135 Feet Per Second has 1.2 foot pounds of energy at 40 yards. Start that same pellet out at a whopping, shoulder busting 1330 fps and it only has 1.4 foot pounds of energy at the same distance. Most pundits consider two 1.2# hits enough to break a bird with 80% reliability. Three 1.2# hits give 95% reliable breakage. Increasing single pellet energy to 1.4# does not change the number of hits required, but it does increase the percentages very slightly.

At 40 yards a #7 1/2- starting out at an ultra mild 1135 fps has the same energy as a #8 starting out at a less comfortable 1275 fps. There is no meaningful difference in energy at 20 yards for #9s whether they start at a “light” 2 3/4 dram 1150 fps or a “heavy” 3 dram 1200 fps. The #9s lose velocity so quickly that both speeds register 1.1 foot pounds of energy. You have to go to a second decimal place to see the difference. The target cannot do second decimal place calculations and does not care a whit.

What about those loooong 60 yard crossers? #7 1/2 s started out at a mild recoiling 1135 fps are doing 540 fps at 60 yards. The same pellets started at a neck snapping 1330 fps are going 580 fps when they whack that 60 yard target. The difference is only 40 fps at the target. The difference in energy is an tiny .1 foot pound.

Leads: OK, so we know that figures lie and liars figure, but here is some more really good stuff to make you earn your Junior Technoid pocket protector: It takes a #7 1/2- pellet starting at 1200 fps .139 seconds to reach a 40 yard target. It takes a #8 pellet .141 seconds to do the same. If that target is crossing 30 mph (about the average speed for a normal target in mid trajectory- even though you may think that they are faster), the difference in lead is going to be a whopping 1.06″! That is 1+ inches, not 1+ feet. So much for changing pellet size to get there faster.

What about increasing velocity for those long ones? #7 1/2-s started at a limping 1135 fps take .145 seconds to get to the 40 yard mark. A 30 mph crosser would have moved 76.56″ inches in that time. That is the actual lead required to break the target for that load. Now if you raise the speed of that load to a howling 1330 fps, the shot will take .129 seconds to reach the target. The target lead will be a calculated 68.11″. In exchange for going from a light load to a very heavy load you have gained less than 8.5″ of lead. The difference between a 2 3/4 dram (1150 fps) load and a 3 dram (1200 fps) load of #7-s is about 2.6″ of actual lead on that same right angle 40 yard crosser.

Now, instead of being a right angle crosser where the deflection angle is at its maximum, if the target is quartering away at 45 degrees, the lead advantages will be cut by half. You can divide all those previous numbers by two. No, we are not getting into shot string here. Trust the Technoid when he says that adding 200 fps of velocity to the load will not dramatically alter the normal 10 to 11 foot long 40 yard shotstring. We will save discussion of that for another time.

One final thought to muddy the waters- #7 1/2- shot started at 1200 fps drops about 4″ at 40 yards and about 11″ at 60 yards. What! You only worried about pellet energy and lead, not shot drop? You should really worry about that one too. Then there are the very real effects of wind on those little pellets. Do not forget barrel flip, heat mirage and a ton of other stuff. Hang in there Junior Technoids. It is going to get deeper and thicker before you are led out of the woods.

In the meantime, you could probably do a lot worse than loading all your shells to about 1150-1200 fps and practicing more. Aye, there’s the rub -adub.

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One Response to By The Numbers…

  1. jon bastable says:

    “By the Numbers”…very interesting piece – thanks for the info.. I hate shooting those heavy loads!

    Jon

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