300 blackout questions

[Richard Jones]

Can you replicate that 'tumbling' in gel? Is there video somewhere of this?

 

[Dufas]

Tumble on impact. Normal gyro response - tries to go 90 deg. to rotational path when - interrupted. Not a whole lot of energy in spin, still rotational velocity ^2/2 x mass. Same with fast twist 223. Creates more damage even though not a DRT.

 

[dellet]

Can you replicate that 'tumbling' in gel? Is there video somewhere of this?

I have not tested the 220 rn specifically, but other round nose bullets. There is a trend, and it doesn’t have anything to do with gyro or spin stability. The 220 Sierra is marginally stable at1000fps in a twist slower than 12. I would be surprised if it was not stable at 500 yards in a 1/12.

What seems to be the cause is angle of entry, center of gravity, and most important nose shape. A round nose bullet will not poke a clean hole in anything, including air, it tears a hole do to blunt force. Unless the bullet hits exactly aligned with the weight mass behind the nose, the force wants to pivot on the ball shape.

Most of the bullets I recovered in gel rotated 180* and stopped. The principal is kind of like throwing a dart backward. It rotates until the heaviest part, the point is traveling forward. With bullets the trend seems to be the more needle like the point is the less likely the less likely the bullet will tumble on entry.

I’ve never compared a round nose boat tail to a round nose flat base to see which tumbles sooner. More likely to flip. Could be interesting.

Gel can be deceptive because of the elasticity it has. There is a certain amount of spring back. Jacketed bullets that mushroom and are not bonded will often strip the jackets. What happens is that the bullet stretches the gel, because agin it’s not poking a hole it’s tearing one, when the bullet stops and the gel snaps back, the mushroom lead core stays behind, the jacket is pulled off and is about an inch or so behind the core. This also makes actual penetration depth hard to measure. That’s why the “calibration” of the gel is important for comparison purposes.

I’m not aware of high speed video of bullets as they meet steel or or gel that are able to capture the bullet starting to pivot. What I have seen is sound channels in gel that within 1/4” are obviously an oblong tear, vs a round hole.

What might be of interest, and I’ll look for a video of the subject, but there plenty out there, is arrows shot at various hard material. The objet is to point out the importance of a properly spined arrow and a square hit. The difference in the delivery of energy on impact eye opening.

Hope that helps

 

[spaniel]

Shoot the Maker Rex subsonic, you won't have to rely on tumbling.

 

[tommeboy]

Kentucky Range Time

I hope you'll enjoy my sometimes out-of-the ordinary looks at reloading, ballistic gel block testing, gun reviews, simple repairs and my other gun build/mod projects. Also, some EDC, prepping and looks at useful knives and tools to have around. If you like the content, be sure to subscribe...

www.youtube.com

This guy has some good vids with gel test

 

[Richard Jones]

Shoot the Maker Rex subsonic, you won't have to rely on tumbling.

Pretty sure I never would, but thanks for the bullet steer.