Leads For Shotgunning


Dear Readers,

Kian is an old Canadian shotgunning friend of mine and an engineer by profession. He recently asked me for some time to distance figures for shot pellets. Here is what he came up with. You will find it interesting. It certainly explains why those looong faaast ones are so hard to hit.

Bruce Buck

Dear Bruce,

Thanks for the info. It looks like the drag coefficient that I took out of a textbook was about right after all. Now for the point of the exercise.

What I calculated was the distance that the target covers in the time it takes for the shot to reach it (not, strictly speaking, the perceived lead). How you arrange the happy coincidence of the shot string with the target is your business. The reason that I needed the deceleration of the shot was that I calculated the time for the shot to go the distance required, including the deceleration of the shot. The interesting part is in seeing what factors can significantly alter the result. I would suggest that anything over 6 inches is significant, anything over a foot is probably a miss, based on one of your “Technoid” columns, suggesting that the true effective area of a shot pattern is about 24 inches diameter.

What follows below is the distance the target travels in feet in the time that it takes the shot to reach it for #7 1/2 shot with a initial velocity of 1200 ft/s at ISA, Sea Level (59 F, 14.7 psia) air conditions.

Target
Speed
20 mph 30 mph 40 mph 50 mph 60 mph 70 mph
Dist
To Target
10 yds 0.8 ft 1.2ft 1.6 ft 2 ft 2.4 ft 2.8 ft
20 yds 1.7 ft 2.6 ft 3.5 ft 4.3 ft 5.2 ft 6.1 ft
30 yds 2.8 ft 4.2 ft 5.6 ft 7 ft 8.4 ft 9.8 ft
40 yds 4.1 ft 6.1 ft 8.1 ft 10.2 ft 12.2 ft 14.2 ft
50 yds 5.4 ft 8.2 ft 10.9 ft 13.6 ft 16.3 ft 19 ft

Yes, that’s right. If you are shooting at a 70 mph target at 50 yards, it will travel 19 feet before the shot gets there. You can also see that you’d better estimate the target speed within 10 mph for any shot at 20 yards or more, if the speed is greater than 30 mph.

Some other interesting comparisons:

Cold days (20 F instead of 60 F) don’t seem to affect the time or distance significantly until you are at 50 yards with a high speed target. I haven’t done Mexico City yet.

At 30 yards, there is starting to be a significant difference between a #9 pellet, a #7 1/2, and a #5, the larger the shot, the less lead is required

If you are planning to use shot with a significantly higher velocity for hunting waterfowl than what you use for target practice, you had better practice with the higher velocity loads a bit before the season. The difference between 1200 and 1400 ft/s with a 7 1/2 pellet is about a foot at 30 yards with a 50 mph target.

With a high speed (70 mph) target, mistaking the distance by even 10 feet can cause a miss (even at 10 yards distance).

Yes, Virginia, steel #2 seems to match lead #5 out as far as 50 yards. That doesn’t necessarily mean you want to use it.

Anyway, I thought you’d be interested. If you want any more detail, I can send it to you. If you have any other scenarios you want to investigate, just let me know.

Kian

Dear Shotgun Report readers (again),

One final point now that Kian has given you the real numbers. In order to keep things simple, I suggest that you not use feet or meters to describe your leads. Use the new and improved Technoid method.

It is simple. There are only three leads really worth considering. They are “Volkswagen”, “Buick Park Avenue” and finally “Yellow School Bus”. All leads fall into one of these categories.

Well, perhaps that is why Kian has always shot better than I do. Thanks for the numbers, Kian.

Best regards,

Bruce Buck
Shotgun Report’s Technoid
(Often in error, never in doubt.)

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3 Responses to Leads For Shotgunning

  1. I just got a migraine reading that……………………………

    Like

  2. Steve Handerer says:

    Morning Bruce. Very interesting data. Looks similar to what I see. Are the numbers the same for a horizontal barrel compared to say a 60 deg high crosser from a tower? These targets seem to require extra lead.

    Like

  3. Parker says:

    Great info for 1200 FPS but need 1145 and 1250 for comparison, please!

    Like

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