Speer 30 cal 165gr BTSP 0.520 BC overly optimistic....?

[98s1lightning]

I'm a little skeptical that the Speer 30 cal 165 BTSP ballistic coefficient is "overly optimistic". They advertise the BC of 0.520.

I held it next to a Nosler Accubond 165 and it is much shorter and looks to be a lesser design. From what I understand Nosler knows there ****. The Nosler BC is advertised at 0.475 even tho it's longer and more streamline?

 

[LRDGCO]

Skepticism about the claims of marketing departments is always well founded.

But any BC difference between the those two bullets isn't going to matter this side of 500 yards. Do you even have a place where 500+ yard shots are possible in Maine?

 

[98s1lightning]

No I never intend on shooting past 500.

While I agree with you it matters more on long range, i think the BC matters at any range the more efficient the better it will fly.

The best example I've seen on BC is look at 300 blackout sub and 45 auto out of a rifle. A 300 subsonic at 100 yds is still accurate even tho it drops a LOT. I bet you couldn't even hit the target with the 45 auto and a hollow point.

 

[JimKirk]

Looking at JBM Calculation ...
The Speer is .477
The Nosler is .475

sounds more likely to me .....

 

[30Cal]

That's essentially the same. I personally think it's a little silly that they publish BC's to three digits given the disparities frequently found.

 

[horsey300]

Skepticism about the claims of marketing departments is always well founded.

But any BC difference between the those two bullets isn't going to matter this side of 500 yards. Do you even have a place where 500+ yard shots are possible in Maine?

I don't know about everyone else and their particular situation, but for me, bc inside of 500 (depending on cartridge) equivocates wind resistance more than drop, drop doesn't bother me at any yardage, but even at 250 in a 20 mph crosswind b.c. can be noticed

 

[jmr40]

There have been some independent labs that have tested many of the bullet manufacturers data and found several that were "optimistic". Many however were pretty darn close. The bullets BC also depends on it's velocity. If you test BC at the muzzle, it won't be the same at 300 yards after it has slowed down. Some companies publish the BC at various speeds, some use the one that makes them look best, and others use an average somewhere between the muzzle and some point down range. Nosler BTW was one of the more overly optimistic tested, Hornady one of the more accurate. I can't recall how Speer ranked, or if they were even tested. Sierra is one of the companies who publish several BC's depending on speed which I think is pretty accurate too.

Small differences in BC probably don't matter. But significant differences can mean much faster bullet impact on game at even moderate ranges. At ranges inside of 500 yards,maybe more, muzzle velocity trumps BC when it comes to bullet drop. But better BC's mean more velocity at impact.