How fast is too fast?

[EOD3]

Hi guys,

I’ve been doing a little reading about hunting with cast boolets and I’m hoping someone can point me to an appropriate data source. I’m looking for impact velocity of various BNH boolets and bullet deformation and fragmentation. There is a little data in the Lyman book but I’d like to find something with quite a bit more data. If you know where I can find any data, I’d appreciate it.

[357maximum]

Honestly the best source for such info is right here. Ask your caliber specific question and the answer is usually swift and forthcoming. When you ask such questions here you get field experience not some regurgitated magazine dribble. You may get a few opposing ideas from time to time, but I have been there and done that is never a bad thing to listen to.

Most of my boolits that have turned brown antlered things into gullet filler have been in 30 and 35 calibers. So far I have been very impressed with 50%lead 50% wheelweight that has been consistantly waterdropped right from the mould for launch speeds of 1800-2200 fps in both the 30's and the 35's.

In my Whelen I run 24-2750fps launch speeds and have went to adding 5-10% nickel bearing railroad journal babbit to the 50/50 to aid in not getting too much "mushroom" when the boolit hits the bone so to speak.

The more specific you are with your question the more apt you are to recieve the answers you seek.

[EOD3]

It seams reasonable that somewhere, someone has put together something like this:

BNH_____YIELD VELOCITY (mushroom)_____FRAGMENTATION VELOCITY

5.0______500 fps_____________________1000 fps
.
.
.
21.0

I wouldn't think caliber would make much difference but the profile might. How much, I have no idea.

I could just guess and go with something between 10 and 21 based on velocity and wind direction but, I'm the kind of guy that hates unturned stones. :-D

[357maximum]

The flaw with your paradiggem thought idea is that different alloys can be blended to equal the same BHN. I can make a 25 BHN boolit out of linotype mix that will shatter on impact or a lead/ww/babbit mix that equals 25BHN that will perform flawlessly. BHN all by itself is almost meaningless.

[Lloyd Smale]

Like was said theres many variables. If your shooting 30 or 35 cal rifles a little deforming (they call it expansioin) is a good thing and even a bullet that fractures on thin skinned game isnt a bad deal as long as it retains enough weight to pentrate to the vitals (look at a nos partition) Alloys like air cooled ww or 5050 ww/pure work well if you can shoot them in your gun without excessive leading. Speed can be your freind with small caliber bullets. For handguns 44 and bigger i feel the bullet is allready big enough and other then fooling around with hps some i really dont want any bullet deforming. A big bore handgun will shoot with the proper alloy to about 1300 fps without worrying about deforming when hitting big bone if you use an alloy that is about 16 bhn or harder. As to handguns bullets fracturing ive never seen it on game with even linotype bullets. Sure they fracture when hitting steel but so does ww. hps and soft nose cast handgun bullets are fun to play with and work great on animals under 500 lbs but when it comes to big boned animals i want penetration and that means a bullet that dosesnt deform. Most of my bullets for those purposes are cast out of #2 or 5050 ww/lino air cooled. Cast any softer or pushed any harder and you cant rely on the a 100percent not to deform. By the way ive seen more water dropped ww bullets fracture then i ever have linotype bullets even from rifles. Like 357maximum said theres just to many ways to obtain a hardness level to put straight accross the board velocity limits on anything.

[EOD3]

Thanks guys, I should have known there wasn't going to be a straight-forward solution. Now that you've pointed out the ELEPHANT in the room, even I can see it. :oops: The metallic structure would obviously contribute a great deal to the bullets properties.

I've found one (I presume reliable) source claiming BHN * 480 = Yield Strength. Unfortunately, yield strength is a little too vague as a unit of measure.

The casting I'm planning to do is limited to 45/70 rifle, 45 Colt rifle + revolver, 44 Mag rifle + revolver, 357 Mag rifle and revolver and 30 cal. rifle. With the exception of the 30 cal, I doubt velocities will go beyond 1600 fps and a lot less in some circumstances. I'll use gas-checks on the 30 cal. bullets but I'd prefer to shoot flat base bullets in the big-bore launchers. Maybe it's time to pick up a few bags of sand and a trash can.

[GabbyM]

About the only formula for expansion I've seen is this one.
You will start to get deformation when velocity exceeds (BHN# * 100 = Vx).
Given that simplistic formula if you have a BHN #10 alloy any velocity over 1000 fps will deform the bullet. Since Elmer's 20-1 alloy 44 mag loads would expand a SWC bullet a little bit. With more brittle alloys when velocity exceeds that number you may start to see noses break off instead of a pretty mushroom.

[pmeisel]

I have read a poster's opinion on a forum (might have been this one, not sure) that BHN should be greater than or equal to (velocity in fps/100)+2....., not so dissimilar to Gabby's formula above. This was primarily to avoid leading.

As previously mentioned, though, the alloy and method that gets you there will matter in bullet performance.

Good luck with the sand and the trash cans, and let us know your findings!

[Blammer]

I'm thinking that with a few of your choices you should be able to exceed the 1600fps mark.

[EOD3]

I'm thinking that with a few of your choices you should be able to exceed the 1600fps mark.

Sure enough but I prefer big heavy slow bullets over little fast bullets. IMHO, the only reason "premium" bullets exist is people not using enough gun.

[EOD3]

Thanks for the help guys. If I run across any other useful data, I'll post it. :smile: