The relationship of bhn, velocity, and expansion with cast

[freebullet]

I did some hollow point tests in the gp100. I don't have the pictures available just yet.
I used alloy around 10bhn fired them into water filled milk jugs, yes I know that means little compared to on game performance. I used the mp359-125 over 10.5gr of hs6 with modified Felix as pan lube. They opened up real nice and blew up the jugs for quite a show. The recovered boolits weighed avg of 76gr. The longer range past 30yds accuracy fell off. I think due to the soft alloy at high speed and it was plain based. What hardness level could I use and still get expansion?

It brings forth some questions about expansion capacity of different bhn driven at different velocities. Are there any hard or fast rules, guidelines, links, or tips?

 

[Ian]

There are a lot of anecdotal data points out there that can be sort of assimilated into an image of what/when/where to use, but I think the most important thing of all is to note that "BHN" in and of itself means very little. Straight wheel weight alloy, Lyman #2, 16:1 lead/tin, and various low-antimony, heat-treated alloys all behave differently at different velocities, particularly when used for hollow point bullets.

Metallurgically-speaking, BHN equates to a metal's "toughness", not exactly "hardness". For HP bullets, toughness and malleability are both desirable for weight retention so that the nose doesn't split apart and break away in bits. Antimony is a brittling agent, but also ads toughness beyond what tin alone can do. If you 10bhn bullets suffered from fragmented noses, examine the bullets and see why: Are there rough fractures where the "petals" broke away? If so, perhaps you need a touch of tin in your mix to reduce brittleness without adding too much toughness.

My favorite trick for getting HP expansion AND accuracy is to take an alloy that has something around 2% antimony and less than 1% tin and give them a mild heat treat/water quench. You'll end up with something that can take rifle velocities yet expand well at 1k fps, depending on how hot you get them before the quench.

Depth and shape of HP pins have a lot to do with how an HP design behaves, so take that into consideration as well. Sometimes a deep, small HP is good, sometimes a cup point works better.

You can tell a lot about what an alloy will do when shot by putting a bullet on an anvil and smashing it with a hammer.

 

[Brad]

Failing to own an anvil I use the garage floor.
Like Ian pointed out I prefer a "softer" alloy with low antimony that is then water dropped or heat treated to get the BHn high enough to alloy for the velocity I want.
Trial and error will become a requisite part of all this as actual alloy content, heat treat level, HP size, and velocity all are variables that come into play.
I will say that I find a bullet that stays together will on the berm will tend to hold together well on game. If the HP blows apart on the berm then it will likely do so on game.
I am speaking in general terms and being a member of the same club as Freebullet I know what his berms are like. Just remember that dry berms interact different from wet ones, HP bullet even more so.

 

[freebullet]

Those didn't break off the tips, but rather over mushroomed just a bit more than I'd like. They may well be softer than I thought.

I'll see if I can get the pics off the SD card. I tried to change my avatar after I observed others now having them, it didn't work though. Said my pics are too big. Not sure if I'll be able to post them.

 

[358156hp]

My avatar was a bit large and it appears that the board sized it down a bit for me.

 

[Brad]

I too resized my avatar photo.
Your HP may be a bit soft but that is easy to fix. You could water drop them or add a tiny bit of antimony to them. Like a 1/4 percent to start.

 

[freebullet]

I'm not sure if I can size down a pic on my phone, that's where I post from 97.93462% of the time.

I can definitely make them harder and the neck sizing trick form Rick could make a nice improvement as well.

 

[Brad]

What brand phone? There is a free app for iPhones I use on the iPad to resize photos.
If an Android you are screwed. The majority of members here are Luddites who either use a flip phone or don't own a cell phone.

 

[freebullet]

"If an Android you are screwed."

Yep.

I'd love to not have a phone. It would make it real tough to run my business though.

Makes me think back to the car phone days. I wired it to honk the horn so we would hear it outside the truck on the job. Boy did that get us some looks occasionally lol.

Guess that forces me to turn on and update my laptop.

 

[Brad]

Gotta be a freebie app for Android.

Or email me the photo, I will resize it and send it back to you.

 

[Rick]

When did you last try to upload an avatar. It wasn't working until I think Sunday, before that ANY picture was too large which is why no one had an avatar until then.

 

[Ian]

What brand phone? There is a free app for iPhones I use on the iPad to resize photos.
If an Android you are screwed. The majority of members here are Luddites who either use a flip phone or don't own a cell phone.

What can I say, my flip-phone was a huge upgrade from the bean can and string, but that's as far as I'm willing to upgrade because few multi-purpose tools are particularly good for doing any one thing. I have a phone for talking, a camera for taking pictures, and a computer for this.

 

[freebullet]

Ya, I can do most stuff right from this phone. It's just not the same as a computer though.

I tried again after sizing it down and got the following error message.

The following error occurred:

The contents of the uploaded image do not match the file's extension.

 

[Brad]

See, Luddites.

I will admit that usig my phone for access makes it nice when eating lunch at work. Our work computers have very limited internet access and I can assure you this site isn't on the list.

 

[Rick]

What can I say, my flip-phone was a huge upgrade from the bean can and string, but that's as far as I'm willing to upgrade because few multi-purpose tools are particularly good for doing any one thing. I have a phone for talking, a camera for taking pictures, and a computer for this.

Great minds think alike. Well except for the cell phone, I fired the cell phone company right after I retired. No more leash for me. I have a computer for this and my home phone has a wire attached just like Alexander drew it up.

 

[Brad]

I have a cell phone, home phone. Ipad, and a computer.
You name it, I can connect from it.

I NEED all this stuff, you guys would be lost if I couldn't connect!

 

[358156hp]

This is SCARY! Yup, I don't have a "smart" phone either.

 

[freebullet]

I wouldn't quite call it smart.

It works dandy most times though.
I can email, text, take pics, surf, post, control a scanner/copier/printer, call, and a bunch of other stuff I probably don't even know about. It makes a fine tool for managing communications for business.
The problem is the interface between computer to phone needs a bit more polish.

I'll tinker with it and see if I can figure it out. If nothing else I'll test my hollow points on it.

 

[Ian]

Rick, I had a real telephone plugged in for about three days after I got the service hooked up to the barn about eight years ago. Thing rang off the wall with telemarketers. I got on the DNC list and that stopped some of it, but apparently the Girl Scouts, local HS team boosters, newspaper, and a host of charity collectors and religious solicitors are "exempt" from observing this. I kept the cell phone because, so far, it has been pretty much safe from all that. Now what were we talking about? Oh yes, getting that HP expansion under control......HEAT TREAT, that's what I say. Keep a low antimony, lower tin alloy because it's nice and stretchy, but put a little heat to it (how much depends on how much they need to be toughened), quench them in water, and see how they shoot in a couple of weeks. Adjust as necessary, and take GOOD notes and label everything as you go, trust me on the labeling because none of us are immune from CRS.

 

[freebullet]

Testing testing testing