8.6 Blackout

[LynnJr]

There is no difference between a 300 Whisperand a 300 Blackout that I am aware of and I have both.
Hopefully the 338 Blackout is something new. Anybody have any case dimensions?

[BillyMays]

I think I only mentioned the bullets rpm which doesn't take mass into question? Or where you referencing centripetal force which does? I like to use like units to keep perspective.

My point was exactly that RPM doesn't take mass into question. I was pointing out that a heavier bullet with equal RPM would have more angular momentum- like centripetal force but not exactly the same, however I believe we are referring to the same idea.

[ar15barrels]

There is no difference between a 300 Whisper and a 300 Blackout that I am aware of and I have both.

Depending on whose reamer, there is 0.050" of case trim length variation (case length) among 300 whisper, 300x221, 30x221, 30 fireball, 300 fireball, 300 AAC and 300 blackout.

[SharedShots]

This is assuming the mass of the projectiles is the same. If two projectiles of equal mass hit an object, but one is traveling 3000fps and one is traveling 1000fps, you would expect the faster projectile to penetrate deeper because it has higher kinetic energy.

Projectile weight isn't and has never been the most important determining factor for penetration. Velocity hasn't been it either.


Now consider two projectiles with equal penetration (and shape) but different speeds- the slower projectile must be heavier to penetrate the same distance. This heavier projectile would have more angular momentum than a similar sized lighter projectile at equal RPM, so it would transfer more rotational energy. My thought is that because the bullet has higher angular momentum and low entry speed, when it hits a target it more quickly begins to tumble? I have no idea if this is true. It also doesn't take into account bullet shape or stability, which I think could have a much greater effect- as seen in .223 wounds.

Anyways just my ramblings... I'm sure I've missed something so please correct me

Some of what you said might apply if the projectiles remain in their original shape but then it's usually limited to very heavily constructed projectiles.

At some point, velocity can and does limit penetration because the projectile deforms to a greater degree than the lower velocity one and thus penetrates less.

It is also true that liquids ( blood much like water) resists the travel of foreign objects through it. You can see this yourself with a simple test in a pool. Walking through thigh high water isn't much of a problem, then try to run. Taken to extremes as you'd find with fired bullets the faster the bullet the greater the resistance to the point where the bullet could fragment at the surface while the slower bullet passes through the surface several inches.

I see the rotation energy as more marketing type ideas than reality. The reduction in speed is so great over such a short period of time only with a projectile that deforms would there be much benefit. If the projectile is so heavily constructed that at much higher velocities still doesn't deform then the rotational speed wouldn't matter very much. If however the bullet deforms then rotational speed could be an important factor but then it comes full circle, the deforming bullet tends to penetrate less even when it has greater mass and velocity and this is proven in many tests.

So then, two bullets traveling at different velocities where the bullet deforms could see the slower velocity bullet penetrate deeper than the one with higher velocity. In that case the lower velocity bullet could create much greater damage since it penetrated into vital areas whereas the higher velocity bullet creates a larger but shallower wound.

The difference could be very apparent if one were going after that Cape Buffalo.

This is why you never hunt Cafe Buffalo without your trained twin bother male lions on breakway leashes.

[sigstroker]

They are definitely working on expanding bullets.

https://www.thefirearmblog.com/blog/2018/08/21/discreet-ballistics-8-6-creedmoor/

Because of the fast twist rates destroying traditional bullets, they seem to be concentrating on all copper ones.