Partition BC Discrepancy

[sniper208]

I have some old(er) 200 grain Partitions. I purchased these in the mid-1980's and used the only manual I had at the time, Nosler #2. I do not have the box - I pulled these projectiles to change the load for my current rifle. The old load for the old rifle was with IMR 4831. I'm changing to RL-19. The BC listed in the manual is .584. The BC listed on Nosler's website is .481, as of today. Which is the correct BC? Did Nosler change the bullet configuration and that changed the BC or did the method to calculate BC change over the years? I need to correct BC for these mid-1980's era bullets for ballistics calculations. Thanks!

 

[Anonymous]

Tim,
This is the response that I got from our NoslerCustom Manager:

"The method used to calculate B.C. has changed over the years – actually improved. We now calculate B.C. based on actual velocity degradation. In the mid-80’s we did not have the capability to measure velocity at 100 yds and at the muzzle, plus the time it took the bullet to travel 100 yds.

The .481 number is accurate."

I hope that this answers your question.

-Justin

 

[sniper208]

Thanks Justin - that helps a lot!

 

[JD338]

In addition to what Justin posted, keep in mind that Nosler has evolved over the years to improve the performance of their bullets. This along with improvements in manufacturing,which helps keep cost down, may lead to a slightly different bullet profile and BC.

The older bullets will work fine but I would use the latest bullets for serious load development and hunting.

JD338

 

[Antelope_Sniper]

Yep, todays partitions are not the same bullet as in 1948. Still the gold standard, just not the same bullet.

 

[sniper208]

I'm trying to use Nosler, but for some reason my rifle doesn't shoot Noslers (PT or BT) as well as it shoots Hornady's SST and Interbond (165 & 180 grains). I've tried three different IMR powders, RL-17 and RL-19 with Nosler and the best group was just under an inch. The Hornady's, OTOH, grouped under 1/2". I've tried different seating depths but still cannot tighten the groups. However, even at an inch (acceptable in some circles), the Partitions will do the job on elk. I tried AB's, but only got just over an inch.

As I mentioned earlier, these 200 grain PT's were formulated for my old rifle that I no longer own (S&W/Howa .30-06, 22", 1:10 twist). That rifle got unbelievable results with the 165 PT and the 200 PT (under 1/2"), both with mid-range loads. My Sig .30-06 22", 1L10 twist) shoots Hornady's at near max charge very well (IMR 4350 for the 165 and RL-17 for the 180). Go figure.

Thanks again for you collective help. I'll keep trying... (after I get a job and back on my feet - my hobby costs $$ :lol: ).

 

[Antelope_Sniper]

Tim, guns are like wives.
It doesn't matter what you like.
What matters is what they like.

 

[JD338]

And don't think that Nosler partitions don't shoot.
This group is 4 shots from a 338 RUM with 250 gr PT seconds.

JD338

 

[sniper208]

That looks like the groups I got with my old rifle with Partitions. I wish this rifle did that with Nosler.

 

[Guest]

JD,
Now that's a real shooter load right there. It's what I'm striving for with my guns.
I don't know but that only looks like 2-shots!!!!! :mrgreen:

Don

 

[SJB358]

Awesome shooting Jim.

Keep up the work with PT's, they shoot incredible in every rifle I own. Most groups rival the BT's in accuracy. They group identical in my 270WSM and a few others with just about the same load. Scotty