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Need a hand with practical scenario

Snowman366

Snowman366

.410
Say you have a police sub-station, or a trial witness's home, and you get a tip that MS-13 is gonna do a drive-by with an AK-47 and shoot the place up in the next 90 minutes.

So you post an officer on top of the building with a 12-gauge loaded with rifled slugs, with instructions to dump a round into the lap of anyone who sticks a gun barrel out of a stopped car's window.

I've never hunted deer from a tree stand up in a tree...so I need to ask: If my rifle-sighted shotgun is sighted-in with slugs on level ground, will the POI versus the POA be different if I'm shooting down at street level from an upper story?

I've heard deer hunters say that their slugs strike a bit high when shooting down from a tree stand. Not sure why, though. I understand that Old Man Gravity works on a horizontal plane, and there's cosign error involved...I just don't know if it'd effect a slug shot at that range.

Be grateful for any help.
 
as far as the slug travel, i have no idea.
as far as the ms-13 crew with an AK47,id be on that roof with my BAR. end of problem.
 

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Snowman366 said:
If my rifle-sighted shotgun is sighted-in with slugs on level ground, will the POI versus the POA be different if I'm shooting down at street level from an upper story?
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Affermative, may I ask the yardage ?

Snowman366 said:
I understand that Old Man Gravity works on a horizontal plane,
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Bingo, same with high power rifle, Bow and arrow but all too differing degrees...I've killed lots of stuff on slope, and from perches
 
I'm interested in this too. For some resaeson I stumble over this one when I shoot and have a hard time finding my hold on paper at ranges even between 25 and 50 yards.
 
oli700 said:
Snowman366 said:
If my rifle-sighted shotgun is sighted-in with slugs on level ground, will the POI versus the POA be different if I'm shooting down at street level from an upper story?
Click to expand...
Affermative, may I ask the yardage ?
Click to expand...

At street level, I'd say 50 yards or a bit less.
 
Snowman366 said:
oli700 said:
Snowman366 said:
If my rifle-sighted shotgun is sighted-in with slugs on level ground, will the POI versus the POA be different if I'm shooting down at street level from an upper story?
Click to expand...
Affermative, may I ask the yardage ?
Click to expand...

At street level, I'd say 50 yards or a bit less.
Click to expand...

150',that a 15 story building.
 
LAZY EYED SNIPER said:
Pretty sure that's the run, not the rise... :D
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Yep...50 yards, or pehaps a bit less, from the base of the building to the target's position out in the street.

The sub-stations are usually single storey buildings with flat roofs.
 
whats the height of the building,whats the target distance,whats the slug ammo you are using,whats the weather,all these come into effect.
 
Snowman366 said:
LAZY EYED SNIPER said:
Pretty sure that's the run, not the rise... :D
Click to expand...

Yep...50 yards, or pehaps a bit less, from the base of the building to the target's position out in the street.

The sub-stations are usually single storey buildings with flat roofs.
Click to expand...

i hope he has a 930,,,,,aim dead on.
 
old mossy said:
whats the height of the building,whats the target distance,whats the slug ammo you are using,whats the weather,all these come into effect.
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Well...10 to 12 feet on the building height, the target distance is 50 yards, or slightly less, at street level. The slugs are one-ounce Winchester or Federal Foster slugs, usually the reduced recoil variety and, since this is a hypothetical question, I can't really give you an answer on the weather.
 
Thanks Snowman,

My trig is a little rusty, but if you break the shot down into a right triangle you can use the Pythagorean Theorum to solve for the variable distance when shooting from an elevated platform. If the height of the shooting position is estimated at 12' (A) and the distance to target at gound level is estimated at 50' (B), then the actual distance to target on the downward angle is 51.42' (C). This gives you a variable distance of 1.42'.

So in theory, the difference in your point of impact will only vary relative to the degree of difference in shooting between 50' and 51.42' on a level plane. Taking this into consideration, it doesn't seem that much correction would be necessary.

One other variable I can think of would be that gravity might have an affect on the bullet's ballistics coefficient. When shooting at a downward angle, the force of gravity would certainly counteract a degree of the bullet's negative acceleration. 12ga slugs do have a relatively low ballistics coefficient, but still I can't imagine it would be enough to cause a significant shift in your POA vs. POI in this scenario...
 
If I recall correctly from physics class, gravity works on all objects the same, it is a constant 9.8m/s^2

Golfers, marksman, archers , etc all notice variations when we change from a level path of fire to one that is elevated above our shooting position or one that is below our shooting position. The key factor is horizontal distence.

When shooting at a target 200 yards straight out in front of us, gravity is working on the projectile for the full 200 yards of it travel. If it takes the object 1 second to travel that distence, it will have dropped 9.8 meters before hitting its mark.

Make that same same 200 yard shot but move the target 20 yards out but 200 yards below us off a cliff and gravity is only working on that projectile over the 20 yards. Shooting 1000 yards stright down and gravity will have no affect on bulled drop (aside from increasing its downward accelleration) and you will be able to shoot POA. Same goes for shooting straight up, except that gravity will adversly affect acceleration until it reaches a point where it stops and begind to fall back down at the rate of 9.8m/s^2

The amount of effect gravity will have over that time is also dependant on how fast the object is traveling over that distence. The longer it takes an object to travel the 200 yards the more gravity will affect it over the time of its travel. I.e. an arrow traveling 250 fps will drop in trajectory a lot more due to the effects of gravity over 50 yards than a bullet traveling 3000 fps will be affected traveling the same distence but will not drop as much as a baseball thrown the same distance.

Without calculating it specifically, I do not think the amount of drop you will notice in your scenarino would warrant any special considerations unless the distance and or angle of fire is great.

Just a little side for those bowhunters (and gun hunters I suppose) out there: Many hunters that shoot a bow from a tree stand accentuate the problem buy dropping their bow arm only and not bending at the waist. This causes a change in the draw stroke and sight picture. You want to keep the bow arm, drawing arm and head in the same relative position regardless of the angle od the show.

Also the arrow crosses the sight plane twice. With my bow a 5 yard and 20 yard shot use the same pin. The five yard shot is on when the arrow is arcing up into the sight plane and the 20 yard shot is on as the arrow passes back down. Having set targets at my archery club for a while I was amazed how many people would miss 5 yard shots, esp from a tree stand.
 
Gosh, Mike...thanks so much for the time you took for that detailed explanation. I've got it filed away for future reference!
 
No problem; having spent a lifetime behind bows, I'm well aware of the effects gravity has on projectiles.
 
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