Is there a conversion table?

[JWFilips]

Hi Folks:
Would like to know if there is conversion data / formula for taking a load that has been Chrono'ed with a higher grain weight bullet and converted it into info using a lighter grain weight bullet ( with powder weight and barrel length being the same)
Thanks
Jim

 

[Ian]

I don't know of one. You can often note trends if you spend a lot of time engrossed in load data, observing pressure and velocity trends with the same powder type and different bullet weights, comparing that to different powder types and same bullet weights, and also different bullets/different powders. Look at a starting load with a heavy bullet and a max load with a light bullet in a combo where the starting charge with one is similar to the max charge with the other (respectively), and observe the difference in velocity.

 

[fiver]

if your talking going from something like a 150 to a 125 in a 30 cal rifle you might could make a pretty good estimate by just looking through enough books and comparing them to what your chrono says.

 

[KHornet]

I also don't know of any conversion table, but agree with the suggestion of Fiver and Ian. It might be possible from published load data from various manuals to consider figuring percentages of charge and bullet weights by comparison to higher and lower bullet weights. An interesting thought however.

Paul

 

[358156 hp]

I'm not aware of anything either. With all the potential changes that can be made to lighten a bullet design, I doubt you'd find any kind of formula that would work reliably for all changes. Even published data for similar designs like the Thompsons in varying weights require all new load development.

 

[RBHarter]

About as close as you can get is to be intimate with the curves and clean up of a particular powder .
Lots of book work in all cases .

Triple Shock data would probably be about as close as you would find to anything being consistent from say a 130-150-180 in a 30 cal . Maybe Burger data for the VLD style bullets if they stay to a single neck length intent .

 

[freebullet]

I have a few parameter patterns that work for low pressure handgun rounds, but really wouldn't feel comfortable trying to articulate it safely here. It doesn't always work perfect, but is based on the observations of various manuals & my personally collected data. Always triple check your conclusions when loading outside the box.