Where is 600yd POI likely to move to????

[WildRose]

Thanks fatrack I owe you one!

UPDATE on Superformance powder Sensitivity!

Last month Hodgdon told me that my Hornady 338WM -185GMX Superformance ammo that has MV 3,080fps on the box will shoot MV 2,997fps at ZERO F! That is because the 3,080 was shot at 70 F......that is a loss of 83 fps in the 70 degree drop!
Here are my questions:

Would you assume it to be a LINEAR change for my calculations of speed at 10F, 20F, 30F, 40F etc.......= +11.857fps for each 10 degree change???

IF ZERO F is 2,997fps and 70 F is 3,080fps 90 F should be what....? 3,104fps.

And lastley, lightbulbI think this new speed change will remove that 7" high that I was going to have to adjust for when I went from S.C. 592' Elev. and 90 F to 10,000' and zero F???? What do you think? Am I Good to Go?

There are some guys here with ballistic formulas and calculators that can probably give you a very close approximation with every ten degree change. In fact, you can probably plug that in to your own calculator or the one Len has on the site here and get very close yourself.

If I were estimating though (which is most of my shooting) I would probably assume a steady rate as you are and adjust accordingly. On top of the burn rate change that altitude change is going to complicate things a good bit.

Sit down with the ballistics calculators and set up some tables for a cheat sheet and see how that compares with the approximation.

Then I'd head back out to compare both to some actual field data under conditions as close as you can get to your extremes.

Take then an average based off of all three and you should be extremely close.

 

[rscott5028]

I agree with Wildrose.

If you're unable or unwilling to test, then the linear swag is as good as any.

But, you have to plug in the correct altitude as well as reduced MV.

I doubt Quickload has Superformance modelled or that would be another avenue.

 

[Bart B]

I don't think anybody's mentioned the issue with his scope adjustments. If his scope actual adjustments are 5% off from what specs quote, that's gonna mean a 5% error at 600 yards.

If the scope's adjustments are in inch fractions per hundred yards of range, at 600 yards a 1/4 inch click will move the impact 1.25 inches. . . . .if the adjustments are absolute and have no error. If they're off 5%, one click's gonna move impact anywhere from 1.05 inch to 1.1875 inch. If he makes a 20 MOA come up from a 100 yard zero, impact will move either 95 inches or 84 inches; an 11 inch difference.

 

[T3-OleMan]

I agree with Wildrose.

If you're unable or unwilling to test, then the linear swag is as good as any.

But, you have to plug in the correct altitude as well as reduced MV.

I doubt Quickload has Superformance modelled or that would be another avenue.

Thanks Rose and Bart also, for the info. I use Hornady Ballistic Calc. / 10 and 20 mph cross Winds & the ZEISS Rapid-Z® 800 Ballistics Calculator.
Ran all the numbers for Station pressures/FPS/drops to 1,000yds at temps 0.0F _10F_20F etc...to 70F for 8,000', 9,000', 9,928' & 11,000'.

Got all my scope power settings on the exl. spread sheets so all I got to do is check wind, Temp-Station pres-hg.....and fire a few at 8,000' when I get to CO for 2nd or 3rd rifle this year. I got a 400yd and a 600 yd location beside a dead end dirt road to do my test shots......hope I'm not screwed by other hunt camps in there before I get there like last year. It would have been safe to shoot into the base of the Mts. last year but I got more respect for the guys up the canyon than to blow up their hunting area with muzzle blasts.

LORD help me to get my fumble fingers all going in the same direction!
Come on ELK SEASON!

 

[WildRose]

Thanks Rose and Bart also, for the info. I use Hornady Ballistic Calc. / 10 and 20 mph cross Winds & the ZEISS Rapid-Z® 800 Ballistics Calculator.
Ran all the numbers for Station pressures/FPS/drops to 1,000yds at temps 0.0F _10F_20F etc...to 70F for 8,000', 9,000', 9,928' & 11,000'.

Got all my scope power settings on the exl. spread sheets so all I got to do is check wind, Temp-Station pres-hg.....and fire a few at 8,000' when I get to CO for 2nd or 3rd rifle this year. I got a 400yd and a 600 yd location beside a dead end dirt road to do my test shots......hope I'm not screwed by other hunt camps in there before I get there like last year. It would have been safe to shoot into the base of the Mts. last year but I got more respect for the guys up the canyon than to blow up their hunting area with muzzle blasts.

LORD help me to get my fumble fingers all going in the same direction!
Come on ELK SEASON!

Here's a wild idea for you. We have some guys on this forum that live at those elevations who do a lot of shooting. You might consider just putting out a "help" thread and see if any of them would let you ship them your rifle and a few rounds of Ammo so they can check it for you in the off season while they are out practicing anyhow.

I know if I were in such a situation and you asked I'd be more than happy to do it and there's a hell of a bunch of guys on here that are a lot nicer than I am in general HA! gun)

This forum is full of great resources to help people out, and amongst the most important of those resources are the people we have here.

 

[T3-OleMan]

Good idea WildRose . But, after seeing that FedEx-barry supporter- throw that laptop computer over the fence delivery last year on CNN at I think Christmas time, I would not trust FedEx, USPS or the brown truck with my only ELK gun. The people on here...YES.

I'll just wait and do some kind of shooting by getting there a few days earlier than last year.

 

[Bart B]

I live in northern Colorado and have shot matches at 600 through 1000 yards at elevations from 5000 to 8200 feet. There's quite a difference in bullet drop at these ranges compared to those 100 feet above sea level.

I think that ZEISS Rapid-Z® 800 Ballistics Calculator mentioned is only calibrated for one bullet leaving at a given speed in a given set of atmospheric conditions. Is what its set up for going to be the same for where you use your ammo in Colorado? Otherwise, at 600 yards it'll easily be 5 to 10 inches off at 600 yards from what its calibrated for.

 

[WildRose]

I live in northern Colorado and have shot matches at 600 through 1000 yards at elevations from 5000 to 8200 feet. There's quite a difference in bullet drop at these ranges compared to those 100 feet above sea level.

I think that ZEISS Rapid-Z® 800 Ballistics Calculator mentioned is only calibrated for one bullet leaving at a given speed in a given set of atmospheric conditions. Is what its set up for going to be the same for where you use your ammo in Colorado? Otherwise, at 600 yards it'll easily be 5 to 10 inches off at 600 yards from what its calibrated for.

Like any other reticle you'll still have to make adjustments when you change elevation so dramatically.

The differences though are pretty easy to account and adjust for with a couple of pracice shots at elevation.

Those reticles only provide one with close approximations anyhow, not precision precision.

Once you get it set up right, you shoot at range, note the variances and keep it in a log or comitted to memory and they'll work just fine.

Like any other scope though, practice, practice, practice and keep good notes.

 

[T3-OleMan]

Agreed, with both of you. I spent 8 hours (with interruptions-Thur & Fri) running ALL the different yardages, temps, elevations and averaged station pressures for any shot I might have to take ref the 'one bullet trick'.


I have done a hell of a lot of work for just a 2 < 5 % opportunity. But, if I ain't ready I shouldn't be there. 95 to 98% of my shots will be 'black forrest' with small openings 50yds to 250yds but being 70 I may not be able to climb up that Mt. But once or twice on the hunt. Therefore, in another area 30 miles away, I'll be ready for some oldtimer sit and move, sit and move, sit and move on a 4 mile spine where I can see 1,000yds a lot of the time. I made a management decision on my scope choice to cover the 95 to 98% of shot types, i.e. the Rapid Z 800 for jump shots at 6X to times when I might can range it, set the power to Optimum Power, from my charts and fire within ten seconds. I know it WILL NOT EVER be as accurate as DIAL-UP systems, I don't have good long range PUBLIC areas to hunt so it is perfect for me @ < 8 lbs total. All my shots will be freehand, leaning off a tree or rock or if I get lucky, I may get to lay it on my back pack.. I call this "deal with it hunting". I have some honey holes 9,500' to 10,500' that have always had ELK if I can climb up to them! The problem is they will be easying through and pulling grass some of the time and the first & last 2.5 hrs each day the up and down drafts are trying to stabilize at the tops of these Mts. so I better be ready for a 5-10 second shot before they fade away into the forrest.


Thanks again for all of the input. Finally, after the added Superformance info. on my bullet (70 F 3,080fps and 2,997fps at ZERO F), I'm "good to go".


Just hope I don't go "ready, fire, aim"! gun)
Good luck and pass the AMMO!