no expansion surprised me

[tking308]

Looks like an air cavity in the picture too.

Enlighten me about air cavities.. I'm a noob. My guess is you're saying that when I poured into the mold I did something to cause an air pocket in the boolit. If that's the case, what might I have done?
When I get home, I'm going to look closely at the plywood this boolit hit after going through the water jugs. It hit broadside (keyhole) and went about half way through. I saw the mark on the boolit and for some reason associated it with an 18ga staple head from the air stapler I recently got.

[siamese4570]

If it helps any, I shoot the 330 gr gould hp in my 45-70 at 1300 fps. I use straight stick on ww with no leading and it expands like a marshmellow.
siamese4570

[Socal147]

BHN x 100 = velocity

Good info

Thanks

[BPrezPB]

Enlighten me about air cavities.. I'm a noob. My guess is you're saying that when I poured into the mold I did something to cause an air pocket in the boolit. If that's the case, what might I have done?
When I get home, I'm going to look closely at the plywood this boolit hit after going through the water jugs. It hit broadside (keyhole) and went about half way through. I saw the mark on the boolit and for some reason associated it with an 18ga staple head from the air stapler I recently got.

Would weighing your boolits detect an air cavity? I like to weigh mine to sort imperfections, or so I thought

[NVScouter]

Would weighing your boolits detect an air cavity? I like to weigh mine to sort imperfections, or so I thought

Exactly. I used to get them when I bottom poured. I changed to ladle pour and a use a thermometer now and I'm good.

Weighing them is only real way to spot most of them. It could be just a nick but I'd look again. Has more to do with accuracy then anything.

[Bullshop]

Another way to aid expansion with a hollow point is if for some reason you feel the impact velocity may be too low for the alloy being used. Fill the hollow point cavity with boolit lube.
The hydraulic effect will aid expansion when impact velocity is below minimum required for expansion of unfilled nose cavity.
It works.

[jmort]

Water is a tough test medium, very hard on Boolits/bullets. If water don't open it up the it will not expand in the real world. Further, just because it expands in water does not mean it will expand in the real world. Regardless, shooting Boolits in water is fun.

[taco650]

Sounds like I need to aquire more pure lead. I'm gonna see what air cooled will do too.

I shoot at an outdoor public range and have days off during the week. I go there and scrounge used bullets when nobody else is present. They're just laying on the ground and I just pic them up, take them home, clean off the dirt then melt them down and make ingots and later mix that with my WW lead. I'll pick up jacketed as well as cast. Its more work to do this than buying pre-made ingots but its cheap and I enjoy the recycling aspect, YMMV.

[Wolfer]

Quote, shooting boolits in water is fun.

Well sir that can be a matter of opinion. I've told this story before but here it is again. When I first started casting for my 45 colt I'd heard about gas cutting but had never seen it. Wondering what a fired at full power boolit looked like I devised a plan that I thought was better than shooting into the EZ pool.
I took a 10' stick of 4" PVC and duct taped the end up good. Propped it up on my baler tongue and filled it with water. I backed off a few feet and lined up with the pipe. When I touched it off there was a 4" stream of water fire hosed out of the pipe. Washed my hat off my head and the only dry spot I had was a little strip down the middle of my back.

I did have a good boolit to look at though. I found it just outside the pipe, it went thru the 10' of water and hit a rock hard enough to ding the nose. I was really glad I didn't shoot into the little woman's pool. It was only 4' deep.

I believe member oneshot can tell a similar story if you can get him to. Woody

[waksupi]

It is always gratifying to see another person learn about physics!

[dubber123]

Another way to aid expansion with a hollow point is if for some reason you feel the impact velocity may be too low for the alloy being used. Fill the hollow point cavity with boolit lube.
The hydraulic effect will aid expansion when impact velocity is below minimum required for expansion of unfilled nose cavity.
It works.

Kinda like mine in post #15. Pre-plugged with blue boolit lube. Wood, multiple layers of denim, doesn't matter, they all look the same.

[singleshot]

Enlighten me about air cavities.. I'm a noob. My guess is you're saying that when I poured into the mold I did something to cause an air pocket in the boolit. If that's the case, what might I have done?
When I get home, I'm going to look closely at the plywood this boolit hit after going through the water jugs. It hit broadside (keyhole) and went about half way through. I saw the mark on the boolit and for some reason associated it with an 18ga staple head from the air stapler I recently got.

Here's the facts:

#1 - If air can't escape from the mold as fast as lead is coming into it, you'll get an air pocket
#2 - See #1.

So how do you mitigate this?

#1 - Make sure your mold has functional air vent grooves, if it doesn't you can create some, I think there's several posts around here about how to do that
#2 - Make sure the lead flow is slow enough to facilitate fill-out. On a bottom pour mold, you often need to match the flow to the mold to ensure it doesn't fill too quickly.
#3 - Make sure your mold is hot enough that the lead doesn't harden the instant it hits the mold. This will allow time for the air to escape and ensure mold fill-out.

Hope this helps.

[tking308]

Thanks Singleshot. That helps a lot.

[singleshot]

Thanks Singleshot. That helps a lot.

No problem. I edited the post slightly since there's really only 1 cause of air pockets and I don't think anyone really needed me to be redundant, but the fixes are the same.

[NVScouter]

Thanks Singleshot. That helps a lot.

When I ladel pour now I overpour quite a bit. This helps force out air, and keeps the mold hotter. When I was bottom pouring I just added enough sprue to cover the pour hole. My accuracy has improved too. I didnt notice anything on handgun boolits but this has helped my rifle boolits A TON!

[kevmc]

"Well sir that can be a matter of opinion. I've told this story before but here it is again. When I first started casting for my 45 colt I'd heard about gas cutting but had never seen it. Wondering what a fired at full power boolit looked like I devised a plan that I thought was better than shooting into the EZ pool.
I took a 10' stick of 4" PVC and duct taped the end up good. Propped it up on my baler tongue and filled it with water. I backed off a few feet and lined up with the pipe. When I touched it off there was a 4" stream of water fire hosed out of the pipe. Washed my hat off my head and the only dry spot I had was a little strip down the middle of my back"

LOL That there is Funny, I don't care who you are!!!!
I probably would have first yelled........
HEY Y'ALL, WATCH THIS!!!!

[gray wolf]

LOL That there is Funny, I don't care who you are!!!!
I probably would have first yelled........
HEY Y'ALL, WATCH THIS!!!!

Then I would have said: ( Hey!! Yall wanna give it a go )

[fouronesix]

I decided to see how much my .357 mag load would expand so I shot it through 5, 1gallon jugs of water. This is a Lee 358-158swc cast of COWW +2%tin water dropped. After passing through the water and nearly passing through the 1/2" plywood behind it, ZERO expansion! Darn thing looks new. I chronographed this load at 1395 fps. I was hoping to use this as a deer load but I'd like a little expansion. Should I try air cooled? SOWW?

Really not surprising at all about no expansion. Instead of an unknown alloy recipe, it would be best to use a common frame of reference like BHN. The recovered bullet shows some odd loss from the impact and travel (pockets of missing material!). I do see land and groove marks on the shank and it's impossible to tell about gas cutting around the base since going through the jugs, water and wood is going to smear the perimeter of the bullet anyway.

At any normal impact velocity of the 357, you might look more at a very small flattening of the nose (not the textbook, half shank mushroom- common to higher velocity controlled expansion bullets) as being the norm to expect. If you get to the point of designing a bullet for full expansion at those modest impact velocities, you may run into the unpredictable problem of poor penetration on deer size game. Better to plan accordingly for top accuracy, bullet placement and reliable penetration instead of focusing on expansion.