Sighting in rifle

[ChewyChewbacca]

Not sure if this is the right forum for this but here goes.
I’m sighting in a rifle at 107 yards. The problem I have is that the target is 3 degrees lower at the target than the shooting station. If I sight it in for this range at this angle what would the difference be on a level shooting range? I’m not a mathematician so am hoping that someone can help.
This hunting trip came up unexpectedly and kind of caught me unawares to finding a level spot for this task.

 

[Huntin' Gun]

The math of 3 degrees down over 100 yards, and the correction that would need to point of aim, is far less than the error bars or "margin of error" you're likely to incur with other sources of error such as shooter inconsistencies, ammo inconsistencies and rifle/scope inconsistencies.

How the trajectory is affected by aiming 3 degrees down will result in differences of a fraction of an inch. Unless you're shooting 0.2" groups, it won't matter.

Are the deer you plan to shoot going to be at zero degrees to your rifle when hunting? Or is there a bit of terrain involved?

Don't get all fussed about these little things. Get some ammo. Shoot groups at 1" to 2", the put the center point of the group at 1.5 - 2" above point of aim at 100 yards.

Then go hunt.

 

[silverfoxdj]

The bullet should shoot relatively flat at 100 unless you are way out there seems to me you would be good at any range any one else ?

 

[Huntin' Gun]

If you want to be sure that you will hit your intended target then get some paper plates. Set them up at 200 yards or whatever range you think you will hit 5 out of 5 shots from field positions. If you can't hit 5/5 from field positions at whatever distance, then you should shoot at game at that distance. Do it on a windy day, because the wind doesn't stop just for hunting trips.

 

[coleman1495]

Are you hunting/shooting long range using a turret? If not it isn’t going to matter.

You don’t need a level spot just the horizontal distance component. A lot of rangefinders give you this value already.

My math shows at 3 degrees that makes you 105.9 from target. Again unless you have a turret it’s not worth worrying about.

 

[bcsteve]

I wouldn’t even think of worrying about it.

 

[Ltbull01]

3 degrees slope is virtually meaningless in most practical hunting. I find for most calibres, if you sight about 2" high at 100, you'll be on zero at 200. If you're shooing a 30-30 or similar cartridge, then 2" high at 100 will have you close to zero at 150. It depends on what your comfortable with. If you want a 100 zero, then don't worry about the 3 degree slope angle. But if you set your 100 zero 2" high at 100, set a target at 200 and check to see how it is hitting then make corrections from there. This should then have you about 8 - 10" low at 300. What calibre at you shooting?

 

[ChewyChewbacca]

Right on guys thanks for the replies. Sighted it in for a the 107 yards. Going to be hunting Sitka Blacktail around Prince Rupert so a hundred yard shot is a long one.
I can at least go out now and not having to wonder if I’m going to off 3 or 4 inches.
The only level spots I’ve found is on the beaches or at the top of a climb through the jungle to to hill top across the bogs. I’m taking my range finger that I used back in my bow hunting days and it tells me the yardages to shoot when looking at an angle. So I’m set. Looking forward to this.
Thanks again, I appreciate it.

 

[fingers284]

In practical terms the point of impact that 3 deg at 100 yrds will make is fractions of the thickness of a hair.

 

[Bad Bob]

The math of 3 degrees down over 100 yards, and the correction that would need to point of aim, is far less than the error bars or "margin of error" you're likely to incur with other sources of error such as shooter inconsistencies, ammo inconsistencies and rifle/scope inconsistencies.

How the trajectory is affected by aiming 3 degrees down will result in differences of a fraction of an inch. Unless you're shooting 0.2" groups, it won't matter.

Are the deer you plan to shoot going to be at zero degrees to your rifle when hunting? Or is there a bit of terrain involved?

Don't get all fussed about these little things. Get some ammo. Shoot groups at 1" to 2", the put the center point of the group at 1.5 - 2" above point of aim at 100 yards.

Then go hunt.

This^^

 

[blasted_saber]

How did you even calculate 3 degrees?

 

[Boomer]

With a .30 caliber 150 gr spitzer bullet at 2700 fps, and your target at 3 degrees from level (high or low doesn't matter) the bullet impact shifts about one inch at 1000 yards according to a ballistic calculator. In other words, the difference is too small to make use of in any practical shooting application. To put it in perspective, a single quarter minute click on your scope equals about 2.5" at 1000 yards.

 

[horseman2]

How did you even calculate 3 degrees?

The question was asked at the range and with the rifle on target my iPhone with an inclination app was laid on the barrel to determine 4 degrees.
Conclusion: it's invenereal . . . up mytestical!

 

[Magellann]

The ground elevation and where your deer stops will present you with the shot you have, 3 degrees wont matter as mentioned.

 

[silverfoxdj]

Right on guys thanks for the replies. Sighted it in for a the 107 yards. Going to be hunting Sitka Blacktail around Prince Rupert so a hundred yard shot is a long one.
I can at least go out now and not having to wonder if I’m going to off 3 or 4 inches.
The only level spots I’ve found is on the beaches or at the top of a climb through the jungle to to hill top across the bogs. I’m taking my range finger that I used back in my bow hunting days and it tells me the yardages to shoot when looking at an angle. So I’m set. Looking forward to this.
Thanks again, I appreciate it.

Good luck on your hunt...

 

[Ganderite]

Meaningless. Sight in for about 2" high and go hunting.

 

[MiG25]

Without doing the math you are looking at a horizontal distance of around 103-104 yards. In other words it is likely not measurable.

 

[shatterstate]

If you can hit 4" pie plate at 100 meters you will take game.

 

[Magellann]

How did you even calculate 3 degrees?

Thats what I'd like to know. Its really splitting hairs at that point.

 

[ChewyChewbacca]

To answer a couple of questions that have been asked. One of these days I will get this right and try to give all pertinent info to a question.

I have a range finder that I used for archery that tells me the yardage and the angle the target is at from my position.
When the rifle is level on the bench and a laser is shot down range the dot is picked up at the top of a twenty foot berm. The target is on the board at my head height at 6 feet. The bench is about 4 feet. When I’m at the target and crouch down at the boiler room height of a deer the range finder tells me I’m shooting at angle of 4 degrees at 107 yards.
I figured that if level was at about the 20 foot mark and bench was as at 4 feet, the boiler room at about 3 foot mark at the berm, that would be a difference 17 feet in the trajectory.
Other rifle ranges that I have shot at are set up on the level so that was why reason I asked the question. These deer are wiley little buggers and when the opportunity presented itself I wanted to be confident that my bullet was going to go where I aimed.
The consensus seems be don’t worry about it because it’s not a shooting match with a prize for lots of money and an inch or two won’t matter and I agree.
The rifle I used this year is a Thompson Center G2 6.5 TCU with 100 grain Nosler Partition. I figured that it would be enough for a deer the size of a big dog with long legs and would be a short,light rifle for this country. Turns out that most all trails lead to the beaches so I’m thinking 6.5 Swede with the 100 grain partition for next year for the longer shots.
At this range the rifle zeroed at a 100 shoots 1 inch high at 50 yards.