Can shooting into the wind lift your bullet?

[IdahoRedneck]

I'm working on a drop chart for a new 300 RUM shooting 210 bergers at 2750ish fps. It was shooting 4" high at 800 yards and shooting over the 1000 yard target. So I adjusted the velocity calculation to lower impact and now it is right on at 800 yards but a good foot high at 1000 yards.

Big cat,

I changed the velocity in my shooter program for my proven 300 rum 210 vld load. I realize this is for my gun/scope combo but if I was shootin my 210 load at 2750 the come ups would be as follows....

500 7.5moa
700 13.6moa
800 17.0moa
900 20.6moa
1000 24.4moa

about 20" less correction than your program called for. (26.6)after you adjusted velocity for a zero at 800.......what are your initial drop numbers before you adjusted velocitcy.

Again I think you are have some input errors in your ballistics program.

Remember 4 inches high at 800 is only 1/2 moa. 2 clicks. What sight height above bore did you enter and how did you measure it.....

 

[Bigcat_hunter]

Big cat,

I changed the velocity in my shooter program for my proven 300 rum 210 vld load. I realize this is for my gun/scope combo but if I was shootin my 210 load at 2750 the come ups would be as follows....

500 7.5moa
700 13.6moa
800 17.0moa
900 20.6moa
1000 24.4moa

about 20" less correction than your program called for. (26.6)after you adjusted velocity for a zero at 800.......what are your initial drop numbers before you adjusted velocitcy.

Again I think you are have some input errors in your ballistics program.

Remember 4 inches high at 800 is only 1/2 moa. 2 clicks. What sight height above bore did you enter and how did you measure it.....

I measured the bolt diameter, the scope diameter and divided by half. I them measured the space in-between and added it all together for a total of 1.75" above bore height.

Attached is my first drop chart with the muzzle velocity my chrono gave me. Next is the drop chart with the velocity adjusted to hit where it is supposed to. Take a look at that chart and see if anything I did could be affecting the drop.

 

[IdahoRedneck]

Hell thats how I do it to on scope height.

No offense was ment buddy, just was curious on your numbers, and checking them against a known proven 210 vld load and matching the velocitys, ill admit im not familiar with the JBM software and I cant see what your zero range was. I see the maximum point blank range and maximum height.......what did you put in for your zero distance?

Im creating a profile in my program for your data just to see............. And it will be interesting to see when ya get a new scope on there.

I read through some of your old posts and see where ya switched this scope out with a leupold and all was well. Sounds like you did have a bad apple there.

 

[WildRose]

Yes Sir, that is correct. But nowhere near the amount of the OPs problem in the conditions he was shooting. Nor does it compute to 3 moa low at yards yet a couple moa high at 1000 with the same dial in data.

WildRose I understand and agree about stress and out of true. But the OP has stated the rifle shoots 1/2 moa consistent groups.

I am going to assume , and that is not a scientific conclusion at all. But in my mind from what has been discussed about this condition in this thread. If it were my rifle it would be stripped down of all scope mounting. Rail would be inspected and if no problems found reinstalled with proper bedding to insure it stayed true and flat on top. Then ring alignment checked and scope remounted. Then I would examine with a fine tooth come the actual tracking of the scope and ALL inputted data into the ballistic program especially in regards to scope turret calibration, powder temp variation, BC and I would get a velocity average from an Oehler 35 or a Magneto speed.

The facts that the results from shooting at 100 yards and the results at 900 and 1000 are in complete disagreement indicates multiple problems to me.

It will be interesting for Big Cat to install a new scope with no other modifications and using the same data in the ballistic app and see what results he has then.

Just my opinion for what its worth.

Jeff

I agree. The problem is which I'm relating perhaps not as clearly as intended. Mine would shoot sub MOA for 3 shots and be fine if I let it cool all the way down.

If I did not the accumulation of everything wrong with it suffered badly with heating and got progressively worse with each successive group.

If I chased those groups trying to bring them back to zero it went to hell fast and when I'd come back to re zero I'd be lucky to even be on paper.

I'm with you, I think the problem is in the scope mounting or scope itself just tossing out other possibilities.

 

[Bigcat_hunter]

Hell thats how I do it to on scope height.

No offense was ment buddy, just was curious on your numbers, and checking them against a known proven 210 vld load and matching the velocitys, ill admit im not familiar with the JBM software and I cant see what your zero range was. I see the maximum point blank range and maximum height.......what did you put in for your zero distance?

Im creating a profile in my program for your data just to see............. And it will be interesting to see when ya get a new scope on there.

I read through some of your old posts and see where ya switched this scope out with a leupold and all was well. Sounds like you did have a bad apple there.

No offense was taken! I zero my rifle at 100 yards. I have a new scope on the way. I will lap my rings when I get it here and mount and shoot.

 

[Bigcat_hunter]

Ok I got a new night force NXS. I had the rings lapped for the scope and mounted it. I had to increase the velocity on my dope by 20 fps and it is hitting where it is supposed to out to 1000. I must have a slight cant in my reticle alignment in my scope because it hits slightly to the right by a few inches at long range but for the most part I am very happy.

The rings did need a little lapping but not much. I think the Vortex scope tubes are very sensitive to over tightening and for me at least it didn't track accurate enough to shoot long range. Very happy with the NXS. Makes the Vortex seem like a toy when handling it.

 

[WildRose]

Great news. Yes the tubes on the nighforce, IOR Tacticals, and Mark 4's definitely have much more meat on them. You know you're picking up something substantial as soon as you lay hands on them.

Do you have a Right hand twist barrel and do you have the right twist rate input into your calculations?

 

[Bigcat_hunter]

Great news. Yes the tubes on the nighforce, IOR Tacticals, and Mark 4's definitely have much more meat on them. You know you're picking up something substantial as soon as you lay hands on them.

Do you have a Right hand twist barrel and do you have the right twist rate input into your calculations?

Good question. I'm not sure, I'll have to look. The program didn't ask for that info. Can that effect reticle cant?

 

[Bravo 4]

Next time try locking the rifle down and checking the adjustments on the scope by setting a target (with specifically spaced reference marks) at 100 yards. If it checks out then do as the others said and fire rounds to put it under stress. You don't even have to mount it if you can get something that will hold the scope perfectly still while you turn the turrets. I have found several scopes thats adjustments were not precise without firing a single round, some off substantially.

 

[WildRose]

Good question. I'm not sure, I'll have to look. The program didn't ask for that info. Can that effect reticle cant?

It won't affect cant but it can create the same effect of having your reticle canted.

Think about it this way. If you have a right twist barrel you calculate the spin drift which will be to the right.

If your scope is canted left, it will change your POI in the same way having your windage off will do.

Canted right moves POA left. Canted left moves your POA right. Your POI will then shift in the opposite direction.

 

[Bigcat_hunter]

It won't affect cant but it can create the same effect of having your reticle canted.

Think about it this way. If you have a right twist barrel you calculate the spin drift which will be to the right.

If your scope is canted left, it will change your POI in the same way having your windage off will do.

Canted right moves POA left. Canted left moves your POA right. Your POI will then shift in the opposite direction.

I used a Wheeler scope reticle leveling system which seems to be quite accurate as far as aligning to the bore. I wonder if I adjust my anti-cant bubble level to "counter cant" the spin drift if that would work. Seems like it would.

 

[WildRose]

I used a Wheeler scope reticle leveling system which seems to be quite accurate as far as aligning to the bore. I wonder if I adjust my anti-cant bubble level to "counter cant" the spin drift if that would work. Seems like it would.

Level your scope to be sure it's right and then set up on something you know is perfectly plum.

Check your level while checking the plum line and that will tell you if it's right.

If the rifle feels like it's obviously canted then you never got the scope quite right. Sometimes they move ever so slightly off plum when you tighten the screws.

Always better to have everything correct and input your proper data in your calculations. It takes the guess work out.