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between 1145 fps vs. 1200 fps at 35 yds with 1 1/8oz #8's in performance?
 

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The shot size doesn't matter, it only matters that the load of shot is the same

So, I think you'd just divide the distance by speed.
35 yards is 105 feet so...

105/1145=.0917
105/1200=.0875

Not too much of a difference
 

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You need to know the speed of the bird and the rate of rise. If you know that you can figure how much further and higher the bird would be in the .0042 seconds between one shell and another. It is important to note that the rate of rise will vary depending on your call to shot timing.
 

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The 1145 fps gives a kinetic energy of 1432 ft-lbs

The 1200 fps gives a kinetic energy of 1573 ft-lbs

A difference in measured energy of roughly 150 ft-lbs.

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That is for the entire ejecta.

150 ft-lbs is roughly the torque used on truck wheel lug nuts (steel rims - think F-150) or engine head bolts.
 

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Note, these numbers are at best approximations based on empirical values taken from an old ballistics chart I have.

If you go off the old ballistics chart which account for the fact that the pellets are slowing down the moment they leave the muzzle, the time difference is 0.005 seconds (0.119 seconds for the 1200 fps load versus 0.124 seconds for the 1145 load.)

Estimating from that same chart, the pellets have slowed down to about 680 fps by that point, so the difference is about 3 to 3-1/2 feet of travel for the pellets from one versus the pellets from the other.

Assuming the target has slowed from its initial velocity of 62 fps at launch to about 40 fps at 35 yards, it will have moved about 2 to 3 inches along it's travel path in that 0.005 second time period.

Not enough to make a hill of beans worth of difference.

About...
 

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Disregarding all the possible dynamics of this math problem, isn't the distance of target travel only about 3 to 5 inches?
 

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The shot size doesn't matter, it only matters that the load of shot is the same

So, I think you'd just divide the distance by speed.
35 yards is 105 feet so...

105/1145=.0917
105/1200=.0875

Not too much of a difference
Shot size does matter. And you can't just divide distance by speed since the air slows it down (unless you are shooting in outer space). Also, the faster it starts, the faster it slows down.

From my downloaded Shotgun barrels, Chokes and Ballistics PDF (don't remember where it came from) and interpolated @ 35 yards (chart gives values for 10, 20, 30, 40... yds)

............................Velocity (fps) ......Energy (ft/lbs per pellet) ....... Time to 35 yds (sec).......Drop (inches)

# 8 @ 1145............ 655......................... 1.09............................................... 0 .124 ...................... 3.1
#8 @ 1200........... 702.......................... 1.15............................................... 0.120 ....................... 2.8
#[email protected] 717........................... 1.43.............................................. 0.118 ....................... 2.7
 

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Ah, Neil, you there? Still to damn cold here.
 

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The difference to me is that whichever one of these two loads I am shooting, the competitor who beat me will have been using the other...think about it! Regards, Ed
 

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91 mili seconds versus 88 milli seconds is a difference of 3 milli seconds. Don't think I could twitch quick enough for a difference. Now if it makes a psychological difference then it could be a real difference but in reality there's no real difference.
 

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Actual difference......none

Mental difference........plenty
 

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The only practical difference is felt recoil and any perceived (real or not) psychological difference.
 
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