The big picture:
You have to think a little bit to actually grasp what annealing a bullet's alloy does. Making it softer (what most people think when the word annealing is used in a sentence) is only part of the equation. Giving the alloy elasticity/flexibility/malleability is the true advantage of the heating process that's used in pc'ing bullets.
Typically I water drop everything I cast anymore. 95%+ of my casting is done with nothing more than range scrap. I water drop the cast bullets simply because I cast a lot of hp & hb bullets and the water keeps them from getting banged up/dented/smashed/de-formed. While this is excellent for casting bullets with very little rejects it affects the performance of the alloy's elasticity.
Doing some testing with a snub nosed 44spl. The hbwc on the top right I was using as a standard for the test bed. I've loaded/tested/shot a lot of those 220gr hbwc's turned backwards. I used water dropped bullets in that test & as you can see they didn't expand. The bullet on the lower right was made from 1 part linotype and 3 parts range scrap and water dropped. As you can see the bullet didn't even think about expanding & that load went thru 12+"'s of wet newspaper. The 2 bullets on the left were cast with the same method as the upper right 220gr hbwc (range scrap/water dropped). The only difference was they were annealed in the pc'ing process.
Same 220gr hbwc bullet as pictured above, same range scrap, same water dropped during casting. This time they were annealed in a oven for 20 minutes @ 400*'s. Now the bullets expand instead of shattering. The only difference is the heating/annealing of the bullet. Both those bullets were cast from the same alloy at the same time.
Some extreme bullets made using different alloys and heat & water to enhance the bullets performances.
Some jacketed wc's for the snub nosed 38spl's & 44spl's. The cores were bonded and water dropped making them extremely hard. The exposed brass turns into slicing pedals while the bonded core remains with a huge wc meplate nose.
225gr jacketed hp's for the 45acp that have hard cores (water dropped range scrap) that are not bonded. These bullets are designed to explode causing multiple wound channels. They make huge holes and go thru 9+"'s of wet newspaper. All's that's left of the bullet is the base.
265gr jacketed bullets made with an annealed core for the 44mag. Tested @ 25yds to simulate the velocity (1100fps) of a hunting load @ 75yds showing the impact/performance of a 100yd hit. Note the soft alloyed (heat treated cast core that was water dropped) stayed intact.
Water dropped cast bullets from range scrap that were pc'd . They are shot from a 3.2" bbl'd 9mm chronographed @ 1050fps. The annealing process of the pc'ing process soften the bullet & give it enough elasticity to expand.
Some 130gr 30cal bullets that have a huge hp. Water dropping them makes them vaporize on impact. As you can see the bullet is brittle.
That same bullet in a 308 playing around @ the 50yd line with 1700fps loads. They would leave holes like this 4 1/2" to 5" long in bundles of wet newspaper. The only thing that is recovered is the bullets base with the gc still attached. The bullets vaporize.
What's all this have to do with heating bullets???
Elasticity & malleability are huge in the bullet world. The annealing process does soften the bullets alloy. But there is a lot more to what the annealing process does than meets the eye. A bullet that has the ability to obturate and absorb rotational torque is far more useful that simply looking at bhn #'s.
You can take two different alloys:
97% lead 3% antimony
93% lead 7% tin
Both are 11bhn but the lead/tin alloy is a superior alloy because of it's malleability. The tin lead alloy will take rotation torques from high pressure rifle loads better, obturate better & and run circles around the lead/antimony alloy when it comes to hp/hb bullets and how they perform.
When it comes to pc'ing bullets the alloy bhn is secondary. The alloys elasticity/flexibility/malleability performance allows the caster to use simple alloys that take their cast bullet performance to the next level.
I can use nothing more than 8bhn/10bhn alloy and cast bullets for 9000psi target loads or 50,000psi high powered rifle loads. All's it takes is a little shake & bake pc and some heat.
BHN is meaningless
