Question about ballistics/powder change

[Greyfox]

I currently have a ballistics turret that performs perfectly out to 1000 yards. Can I assume that if I duplicate my load with the same bullet, case, velocity, and get the same extreme spreads when changing to a different powder and primer, (Retumbo to H4831sc), that the impact points will be identical out to 1000 yards using the same turret? Both loads have the exact same point of impact and group size at 200 yards. The caliber is 6.5x284. Thanks.

 

[liltank]

That's a tough call. If everything stays the same, I don't foresee any issues. But each combination will perform differently. Why the change? Have you tried this combo yet? You may want to load a bunch up and go out and test it to see what happens. Let us know, I'm curious.

Tank

 

[Greyfox]

That's a tough call. If everything stays the same, I don't foresee any issues. But each combination will perform differently. Why the change? Have you tried this combo yet? You may want to load a bunch up and go out and test it to see what happens. Let us know, I'm curious.

Tank

The reason for my change is that a new lot of Retumbo is requiring a different charge to produce my original velocity. As long as I am making a change, I fiqure that I will use a powder that I have not seen this issue, trust, and have a large supply. I have tested to 200 yards, and I have been able to duplicate velocity, es, point of impact, and group size. I will hopefully test the ballistics at longer range in the next few weeks.

 

[liltank]

The reason for my change is that a new lot of Retumbo is requiring a different charge to produce my original velocity. As long as I am making a change, I fiqure that I will use a powder that I have not seen this issue, trust, and have a large supply. I have tested to 200 yards, and I have been able to duplicate velocity, es, point of impact, and group size. I will hopefully test the ballistics at longer range in the next few weeks.

At this point, that is all you can do. Test it out and see what happens. I don't know why it wouldn't work.

Tank

 

[Mikecr]

I think it would work also. Atleast at the similar powder temps.

 

[LouBoyd]

There's no point worrying about getting too exact of load match. Ballistic turrets can only be exact for one drag curve at one muzzle velocity. Drag curves are not only a function of the bullet and it's velocity but also atmospheric density and the speed of sound. Atmospheric density is a function of pressure, temperature, and humidity. Speed of sound is almost purely a function of temperature and is only of much interest at transonic velocities.

 

[Greyfox]

There's no point worrying about getting too exact of load match. Ballistic turrets can only be exact for one drag curve at one muzzle velocity. Drag curves are not only a function of the bullet and it's velocity but also atmospheric density and the speed of sound. Atmospheric density is a function of pressure, temperature, and humidity. Speed of sound is almost purely a function of temperature and is only of much interest at transonic velocities.

I agree that ballistic turrets match a specific set of conditions and many shy away from them because of this. I have had great succes using a few turrets matched to the areas I hunt. I have found that the primary variables of altitude and temperature will not require adjustment unless the vary by 2000 feet or 20 degrees repectively. If either one does vary, it's a matter of a few clicks of compensation to maintain my point of impact out to a 1000 yards. For me, high visibility turrets marked in yards is very fast. This is why I'm trying to get an exact duplication of results with my powder change.

 

[LouBoyd]

I agree that ballistic turrets match a specific set of conditions and many shy away from them because of this. I have had great succes using a few turrets matched to the areas I hunt. I have found that the primary variables of altitude and temperature will not require adjustment unless the vary by 2000 feet or 20 degrees repectively. If either one does vary, it's a matter of a few clicks of compensation to maintain my point of impact out to a 1000 yards. For me, high visibility turrets marked in yards is very fast. This is why I'm trying to get an exact duplication of results with my powder change.

Once you need "a few clicks of compensation" then you need a either a range card which matches your ammo and environmental conditions or a ballistic computer so you know how many clicks "a few" is and in what direction. At that point you might as well use target knobs calbrated in MILS or MOA and just look up the numbers on the cards or computer.

The lookup cards or ballistic computer can correctly compensate for any parameter you can measure. It's the parameters you can't correctly measure which will remain the major source of shooting error. Usually the largest error is from downrange crosswind deflection.

Getting exactly the same powder burn other than to achieve the same muzzle velocity is splitting hairs compared to the atmospheric variablility from shot to shot and day to day.

 

[Greyfox]

Once you need "a few clicks of compensation" then you need a either a range card which matches your ammo and environmental conditions or a ballistic computer so you know how many clicks "a few" is and in what direction. At that point you might as well use target knobs calbrated in MILS or MOA and just look up the numbers on the cards or computer.

I think that the lack of flexibility of a ballistic turret with changing parameters is commonly overstated. It is definitely a matter of personal preference,but once I select my turret for the typical elevation and temperature range, corrections on a ballistic turret can be made quickly and from memory. For example, if the temperature drops 20 degrees or more than my turret setting, I know I need to go up 1 click, 400-600 yards, 2 clicks, 600-800 etc. This system has worked for me deer and antelope hunting out to 1000 yards. I'm ok with charts and calculators on the range but for hunting I prefer a faster method for elevation and use the time to get the wind right.