Sectional Density 2 Holes pass through

[52Bore]

If you want 2 holes with a pass thru then you need a heavy or hard bullet.
My experience is only with lead and even with a HP - Heavy lead plows thru at least to 300yds, guess it has too much energy.lol
Weight also plays into SD, like it does with BC.
I did some research on Sectional Density and established a basic chart..

 

[GM54-120]

Over .200 is pretty good for deer most of the time but right around .210 and above is a better choice. Bonding and better construction of course will improve things. Such as solid coppers and partition bullets will usually out penetrate a standard cup/core of the same weight.

I always thought it was rather comical of RW to talk down to the 40cal 200gr SST because the SD is poor but he didnt seem to rag on a 45cal 250gr as much even though its SD is worse.

 

[Whokalouie]

I feel what is most overlooked in figuring a given bullets performance is its metplat.

 

[52Bore]

I feel what is most overlooked in figuring a given bullets performance is its metplat.

A solid certainly helps the bullet to stay together when penetrating..
These folks shooting light HP bullets are finding out.

 

[xdmalder]

Things that escape most people is that as a bullet starts expanding(mushroom) it's sectional density goes south fast. There is a fine balance between expansion, weight, and caliber.

 

[ENCORE50A]

https://www.vcalc.com/equation/?uuid=951b9e0f-4057-11e3-83ad-bc764e049c3d

350gr XLD

 

[52Bore]

Things that escape most people is that as a bullet starts expanding(mushroom) it's sectional density goes south fast. There is a fine balance between expansion, weight, and caliber.

I would think it’s velocity and penetration go south fast upon expansion. Maybe we’re thinking the same, typing differently?
The same projectile with a higher SD will penetrate farther.

 

[xdmalder]

I would think it’s velocity and penetration go south fast upon expansion. Maybe we’re thinking the same, typing differently?
The same projectile with a higher SD will penetrate farther.

I like to think of it this way. A 30 cal 150 grain bullet has the same sd regardless of construction. But a fmj will penatrate more than a ballistic tip every time.

 

[xdmalder]

On an expanding bullet the diameter is changing which lowers the sd and causes drag. The fmj doesn't and plows right through

 

[52Bore]

On an expanding bullet the diameter is changing which lowers the sd and causes drag. The fmj doesn't and plows right through

I’m intrigued- where can I find some data or articles on how the SD changes?

 

[xdmalder]

I’m intrigued- where can I find some data or articles on how the SD changes?

https://www.shootersforum.com/threads/just-how-important-is-sd.70478/

 

[xdmalder]

https://www.google.com/amp/s/www.fi...tional-density-bullet-penetration-truths/?amp

 

[52Bore]

Thanks - good reading.

 

[Whokalouie]

https://www.shootersforum.com/threads/just-how-important-is-sd.70478/

Very informative!