Air cooled boolits at zero degrees

[Snyd]

So last weekend I couldn't go skiing so I decided to cast up some boolits with my new to me RCBS 45-405-fn mould. I do my casting outside in my greenhouse which has no heat. It was about 0 to 5 above. I "air cooled" the boolits which means they went from a hot mould to 5 degree air on a towel. Do you think this would be just like water dropping them? When water quenching we are obviously well above freezing and the water cools the boolits quickly. What about cold air? Think it will have the same effect? My alloy was 50/50 ww/Lino. BHN was about 15 I think after casting (have to check my notes) but last night ( 4 days later) when I tested one it was just over 20 according to my Lee tester. From all I've read, air cooled 50/50 ww/lino should be around 18-19 after a couple weeks of age hardening. It looks like I'll be closer to 22+ if they keep hardening.

[onondaga]

That is pretty hard! If you are looking for higher pressure, higher velocity loading, that will do it. A flat nose will punch meat real hard by itself but that alloy is too hard to expand on meat penetration. I read you are in Alaska, 15 BHN would give you great expansion on nasty bears and other big animals.

P.S. have you ever eaten Musk Ox? What is it like?

Gary

[troy_mclure]

a lot of the hardening in from the rapid cooling of quenching, water absorbs heat 25x faster than air thus cooling the boolit faster than air no matter what temp it is.

[Snyd]

I've never eaten Musk Ox. Moose, Sheep, Caribou, Bear, Salmon, Halibut, etc. but no Musk Ox yet. Sheep is the best. Musk Ox are further north. But, for bear protection and moose hunting or any big heavy or dangerous game we don't want an expanding boolit. We want a 45 caliber or larger with a good size metplat, and no expansion. The bullet needs maximum penetration. Bullet deformation needs to be minimum. This rcbs mould has as small a metplat as I'd want. It'd be better if it were larger but it drops a 420-435 depending on alloy, I'm sizing them down to .452 from .458 and will load them to about 1000-1100 fps in my 454 Casull. The boolit also cycles in my 454 Puma so I'll see what I can come up with. I should gain about 300fps in the Puma. 400+gr .452 at 1100-1400 fps should give 4ft or more of penetration pretty easy.

[Snyd]

a lot of the hardening in from the rapid cooling of quenching, water absorbs heat 25x faster than air thus cooling the boolit faster than air no matter what temp it is.

That's kind of what I was thinking. Water sucks the heat right out of you faster than air. until you get to a certain temperature though. I'd rather be in 40 degree water than 40 below air!

[stubshaft]

Air at -40* won't kill you in 4 minutes. I've been in -40* water, not something I'd want to repeat.

[RobS]

The air temps can affect the hardness of boolits. Straight WW alloy at darn near 8 degrees cast out in my garage resulted in 15-16 BHN hardness where as in the summer months with a 90 degree garage gave me a 13 BHN boolit from the same alloy. Oven annealing those same aged WW boolits at 425 degrees and allowed to stay in the oven to cool very slowly can result in a softer 10 BHN or a bit less boolit hardness. I've tested some annealed 10 BHN WW boolits that held the same reading two months later.

[selmerfan]

stubshaft, just out of curiousity, where and how have you been in -40 water? Unless I'm mistaken, that means you would have been inside a VERY cold block of ice! :)

[frankenfab]

I've been in -40* water, not something I'd want to repeat.

WHoa! You've been frozen in ice? Like a Caveman!:redneck:


:kidding:

[Hardcast416taylor]

I can remember what +45 degree water felt like when it filled my waders when a duck hunting adventure resulted in a slip sideways fall in a waist deep pond!:holysheep:shock:Robert

[sqlbullet]

The lead forms a matrix as it cools. Hardness is acheived as the alloyed metals are trapped inside the matrix uniformly rather than being allowed to migrate. The more rapidly the alloy is cooled, the more uniform the matrix.

That said, I don't know at what cooling rate you achieve the optimum. My experience with lead, plus my education regarding quenching and anealing steels, tell me that water does have an excess budget to realize the goal. Air cooling clearly does allow some migration.

I would expect bullets air cooled in cold weather (below 32° F) from a hot pot to be harder than those air cooled in room temperature air.