300 Win Mag ballistics Q's on bullets and BC for a CDS dial

[excaliber]

I'm finally getting started on a custom load for my 300 Win Mag. I have a Leupold CDS scope that I need to have the custom shop build a dial for.

I was wondering what the real life difference is between the two bullets I'm interested in. They have BC's of .474(Partition) .507(AccuBond) and the factory Federal Trophy Copper(.523) at 2960 fps is what I'm going to compare them to initially.

I used the Hornady ballistic charts and the difference when calculated at the Federal rated speed of 2960 fps is so minimal between these bullets.

Lowest BC to highest
At 300 yards they drop 6.8, 6.7 and 6.6 inches
at 500 yards they drop 39.7, 38.7 and 38.3 inches
at 600 yards they drop 68, 66 and 65.1 inches

Out to 500 yards the difference is minimal. At 600 the higher BC bullets separate themselves from the Partition.

I guess what I'm getting at is what if I decided I wanted to use the AccuBond initially and later found the Partition was more to my liking? Would you be worried that there was a difference at 500 yards of 1" and 2 inches at 600 yards? At 300 yards they are with .2 inches of each other.

This is going to be a hunting load and shots most likely in the 200-350 range most of the time but I'd like to be able to practice out to 600 yards on paper or metal targets.

I doubt I'd ever shoot good enough to worry about 1-2 inches at 500/600 yards.

any advice?

 

[Guy Miner]

Re elevation - those differences are minor. I wouldn't worry about them at all.

Learn your windage. It's the bugaboo of long range shooters...

Regards, Guy

 

[NWBlacktail]

It's kind of the draw back to the CDS system. Those differences listed would be the same if you used the same bullet, but shooting on a warm day vrs. a cold day. Or high elevation vs. low.

I have a CDS, but I left the MOA dial on it. I never got the custom one made, so I have my own drop chart for whatever I'm shooting.

But I wouldn't really worry about it. Or add/subtract a click or two for the different loads after you get the custom dial made.

 

[muleman]

That's what I do. Kept the MOA dial and print shoot cards to match the load and shooting conditions. It also makes it easy if I move the scope to a different rifle.

Scott

 

[wildgene]

...will a CDS dial give you a high probability (90%+) of a first round hit @ 600yds. w/ the 3 bullets??? Yes...

...the listed BC's are guesstimations, your MV's are guesstimations, along w/ altitude density, your "zero", along w/ any number of other factors that are going to affect your hypothetical POI. Better numbers will give you better results, but you just can't escape the gremlins...

...if you want to get anal, you can shoot @ least 10 rounds of each, record the actual MV's & bullet drop, calculate the avg. BC of the 3 groups w/ about the same results...

 

[frankm]

I would highly recommend getting Bryan Litz's calculated (shot through chronographs) BC's for those bullets and use them. More accurate than the advertised BC; those are like HP ratings by the auto manufacturers.

Don't know if the latest book or JBM has Litz numbers for the Federal Trophy Bonded but he definitely has the BC's on the Partition and AccuBond as well as JBM has them.

 

[SJB358]

That's what I do. Kept the MOA dial and print shoot cards to match the load and shooting conditions. It also makes it easy if I move the scope to a different rifle.

Scott

Same here. That's the same way I do all of my scopes. My hunting conditions vary enough from year to year that a CDS made for somewhere in the West is going to be different enough in another place to just make a chart based on my current hunting.

 

[Oldtrader3]

I would shoot the distances with all three bullets and measure. They will be almost guaranteed to be different than the predicted factory BC at 600 yards?