Anyone else ever find this a bit curious? You can take a number of different bullets from different manufacturers that penetrate and expand roughly the same, yet see significant differences in the size of the temporary stretch cavities each produces. In all of the gel tests I've seen, it appears the BH 5.56mm 50 gr TSX load and the Federal 5.56mm 62 TBBC (FBI) loads both produce ENORMOUS temp stretch cavity diameters of 5 inches or greater in 10% ballistic gel. Yet loads such as the Hornady 5.56mm 55 gr GMX or the various 62 grain Gold Dot/Fusion rounds only produce a TSC of about 2 to 3 inches in diameter. Yet all of these rounds expand to about .50" in diameter and penetrate to similar depths. So what accounts for the dramatic difference in the TSC size?

Honestly I just find what shoots the best out of my rifle and shoot it. Gel tests are subjective for the round and rifle.

Taken as a whole, you have to decide what's best for you.

Ex: 50gr TSX and TBBC may do better in temp cavity up close, but do they still have the advantage at 100yds? 200yds? Most gel tests are done from 10-20 feet. They may do better close in due to high muzzle velocity found in each load, but the ballistic co-efficients and sectional density are such that a Fusion, Gold Dot, SMK/TMK, MK318, 62/70 TSX, etc will do better at longer ranges.

Just another way to look at it

Also, the primary wounding mechanism of a bullet is the permanent cavity it leaves after it's passed. While the temporary cavity is a secondary wounding mechanism, it isn't as important as making a big hole.  This page from Hornady gives a basic run down of permanent vs temporary cavities.

interesting, thanks for the info. i've been obsessed with temp stretch for no specific reason but it makes sense that the permanent is the more important factor, along with penetration depth.

That link isnt 100% accurate, especially this little piece here:

Thats only true in non-elastic tissues like the brain and liver. Most tissues, especially muscle, can absorb the stretch and bounce back with little or no damage.

You are right, while its fun to look at the differences in performance between rounds in jello. Realistically Im not too concerned with TSC since it doesnt cause that much damage in elastic tissue. The only time it really matters is when you have the synergy of a fragmenting bullet perforating the tissue surrounding the main wound channel which is then torn up by the following stretch cavitation.

Just because something CAN happen, doesnt mean it does or often enough to be significant.

From Fackler:

http://www.rkba.org/research/fackler/wrong.html