450Bushmaster.net

Looking at both 275s to accommodate. You 1:18 twist I notice a difference in BC between the 2. Now that only equates to about 200 fps at 300 yards but made me wonder. What's the difference in the 2 bullets besides extra driving band in the XPB and the extra .55 BC on the XPB?

BC's as reported by manufacturers are somewhat subjective. Kind of an "arms race". The 450b is like a bumblebee. By all aerodynamic rights, it should not be able to fly as well as it does.

Happy Birthday Christopher Columbus!

Hoot

I have looked at both, diameter and HP depth the same, and other then that top band gone on the TSX, I see no difference.

Have to agree with Hoot.

Thanks for the replies. The BC really doesn't play into the equation for me until I get past 500 yards (with my big rifles) but that was just one of the 2 differences I'd seen. Wonder if expansion velocity is different between the 2?

my guess be no seeing the HP depth the same.

Al in Mi wrote:my guess be no seeing the HP depth the same.

That's what I figured as well

There is a method for determining real world BC, but it requires two chronographs. One at the muzzle and one at the target. Measuring how much velocity is shed will allow you to calculate the BC. Best accuracy obviously depends upon chronograph accuracy and increases the further the two are physically separated. I've never been keen on shooting at a distance through a chronograph as I'm not particularly lucky.

Hoot

Barnes messed up their website listing of their 451 pointy bullets. This may perhaps be contributing to some confusion.

Here's an image that is a composite of the bullet images and information supplied for the TSX-450B bullet and for the XPB-460 S&W bullet.
.

.
Notice that the Sectional Density (S.D.) is the same for the 275-grain TSX and the 200-grain XPB. This is incorrect. All 275-grain bullet of .451 diameter have the same sectional density. It appears that whoever inserted the data for the TSX bullet copied the S.D. and B.C. values from the 200-grain XPB bullet.

As a guess, the Ballistic Coefficient values for the 275-grain bullets will be almost identical.

A minor problem is that the S.D. and B.C. errors supplied by Barnes for the TSX bullet will propagate through product listings for vendors of the TSX bullet. This is already the case of the listing on Midway's website, which shows the TSX with the incorrect S.D. and B.C. values.
--Bob
edited to update image url

Hoot wrote:There is a method for determining real world BC, but it requires two chronographs. One at the muzzle and one at the target. Measuring how much velocity is shed will allow you to calculate the BC. Best accuracy obviously depends upon chronograph accuracy and increases the further the two are physically separated. I've never been keen on shooting at a distance through a chronograph as I'm not particularly lucky.

Hoot

Wonder in a Lab Radar would track a bullet 100yds?

Al in Mi wrote:

Hoot wrote:There is a method for determining real world BC, but it requires two chronographs. One at the muzzle and one at the target. Measuring how much velocity is shed will allow you to calculate the BC. Best accuracy obviously depends upon chronograph accuracy and increases the further the two are physically separated. I've never been keen on shooting at a distance through a chronograph as I'm not particularly lucky.

Hoot

Wonder if a Lab Radar would track a bullet 100yds?

I've seen velocity graphs of one as it tracks the bullet downrange but I don't think it is useful beyond about 100yds. The return strength of the reflection may be stronger with a flat based larger caliber bullet, so perhaps the 450b range would go a little further before the usable return is lost in the background noise. I'm surprised that some hobbyist hasn't modded one of them to utilize a bigger (higher gain) dish. Lots of abandoned DSS satellite dishes across the countryside.

Hoot