Different State - POI Change....is this normal?

[JDD]

Where are you getting that information?

Back in the day before cell phone ballistic programs real shooters had to do these calculations with pen and paper. Any of the old time sniper manual both military and police had such data.

 

[SilverbulletMAG]

Back in the day before cell phone ballistic programs real shooters had to do these calculations with pen and paper.

What is the formula/calculation used that comes out to 1 MOA difference for every 20 degree temperature swing?

 

[jdavistx]

What does your ballistics program tell you when you have a 40deg temp differential, 2100ft altitude differential, Temp of ammo? etc. It all adds up. The best program comes from Applied Ballistics. Others are cheaper but you get what you pay for. Use a Kestrel for taking data? Brian Litz has lots of good info out there.

You've already talked about indoors vs outdoors and the different setup.

My best advice would to be to change 1 variable at a time.

BTW: Handloads or factory? Factory loads change between boxes. You have to figure out what your gun likes to eat.

I also shoot a 7mm Rem Mag. Berger 168gr Hunting VLD's. 2995fps. 0.258 MOA with Nosler brass. Your receipe will be different but I offer the attached file.

Best of luck in finding your solution. Pretend you're a sniper and you won't chase wounded animals.

Just my thoughts, subject to good advice.
JD

 

[jdavistx]

What is the formula/calculation used that comes out to 1 MOA difference for every 20 degree temperature swing?

Depends on the gun and load. I would suggest Applied Ballistics. They actually do field testing to look at BC over velocity, wind et. all and factor that into their program.

It's pretty complex and sometimes makes my head spin.

 

[jdavistx]

maybe cuz most of New York is high and too far to the left!

Alright, let's not get personal...... but that's **** funny.

 

[jdavistx]

I am not sure where the Hill Brothers got there info but I have seen very similar from a lot of different books. This shows temp can change your POI 2 MOA down and altitude can change .5 MOA up. I want to say from recollection these are based around the 308 cartridge. My guess is humidity had a little to do as well. Indoors maybe 60%RH and outdoors in drizzle 99%RH. And high humidity/rain can move impact up as well.
https://www.hillpeoplegear.com/Education/Articles/Rifle-Cheat-Card

If you're only shooting 1/2 MOA on a LONG range hunting forum. Something is out of step.

 

[User4302021]

Can you provide support for that statement. I'm not claiming it isn't true. But I'm curious as to it's logic. As an engineer, and a pilot, it defies my logic and experience. As a pilot, I don't think water droplets could move fast enough to get "cleared" out of the path. I've been in supersonic jets and got water on the canopy going through rain. Would that be through vaporization, or pushed by the pressure wave, or what process? And as an engineer, I know there is no free energy. Even the act of vaporization or pushing anything, in any way, takes energy. That energy would have to come from the bullet, which would impart a negative trajectory on it. But I could be wrong.

The shock wave in front of a supersonic bullet is caused by the bullet compressing the atmosphere in front of it. This shock wave breaks up and clears any droplets that might be in it's path.

The shock wave is present whether there are any droplets or not, the droplets do not touch the bullet and do not add any extra resistance to the force acting on the bullet.

 

[jdavistx]

I think you have to look at the relative mass ratio between a water drop, a plane under constant thrust which you can steer and a bullet running at Mach 2-3. I'm a curious engineer also. E=1/2mvE2. Of course, once you go supersonic it changes.

 

[Hookdown]

The shock wave in front of a supersonic bullet is caused by the bullet compressing the atmosphere in front of it. This shock wave breaks up and clears any droplets that might be in it's path.

The shock wave is present whether there are any droplets or not, the droplets do not touch the bullet and do not add any extra resistance to the force acting on the bullet.

You just stating something is not what I would call "supporting evidence." This link comes from a physics forum. These guys eat, sleep, live this stuff. They seem to side with my view that, all else being equal, additional bullet energy must be expended when shooting through visible moisture, regardless of whether the water touches the bullet or not. Thus the bullet would impact lower.

https://www.physicsforums.com/threads/the-effect-a-raindrop-has-on-a-bullet.679281/

 

[jdavistx]

It's called drag and what is the air density?. What it the differential in drag with BC @ velocity? Not in a lab, but in field conditions? Sorry, not trying to create an argument But If I may ask a question.

When you are landing in inclement weather, what is the variable that most worried you? Wind? Of course, air density/rain drops the bullet/plane. But how you gonna land the plane?

 

[James L Holzhauer]

Moot issue. Its off. Adjust your scope and if it stays on target, it was just the travel. At 100 yards environmental factors should be very minimal except in harshest conditions.

 

[jdavistx]

I did. LONG range is now 100 yards?

 

[User4302021]

These guys eat, sleep, live this stuff.
https://www.physicsforums.com/threads/the-effect-a-raindrop-has-on-a-bullet.679281/

Read the whole thread, watched all the videos. Those videos are highly suspect, and those guys are dorks.

If I were you, I'd look elsewhere to support my argument.

 

[Nowoolies]

try asking a army sniper sights in at home range then travels thousands of miles
and use's his rifle never a issue , ive never had your issue
just about 100 % its airline baggage handelers