Pressure casting HP boolits from bottom pour

[1Shirt]

I am a firm believer that the hollow point version of a boolit is potentially and inherently more accurate when properly cast than is the non HP version of that boolit. I have for a number of years weighed all of my HP's of all cals and weights for rifle boolits, from 22's thru 45's. The little ones 22's & 6MM's, I segregate on a small digital scale to exact weights, and store them accordingly load per exact weights. For 6.5' thru 7MM', I segregate to within .2 grain, and for 30s to within .3 gr. For my .375's for hunting within .3gr, but for target I want exact weights. For 44's .3 gr. is fine, and for big heavy 45 cals to .5 gr for plinking/target work, and to .3 for hunting. I have always preferred to use a bottom pour 20 lb pot, rather than hand dipping, and have have a 20 lb pot or two for well over 40 years. Now to the issue, of pressure casting from a bottom pour pot:

Over the years I have just used a non pressure method of casting, and carefully inspected boolits prior to sizing and lubing, discarding and remelting the culls. However, with HP's visual inspection is far more of an issue, due to the nature of the casting process. As a result, and over the years, I have learned that pressure casting with a rhythm for consistency produces far closer weight tolerances for HP's than non pressure methods. My method of pressure casting HP's is to insure the cavity is full, then drop the mold a bit to allow a small sprew to form. I have found that this produces the most consistant weight of boolit. Using this method, on smaller boolits, I seldom have a variance exceeding .5gr, and often on batches of 100 or so, .3 gr. is not uncommon. Little 22s in my experience require exact weights for consistant accuracy, and due to the small amount of lead going into the mold requires that you develop a technique just for them. I also recommend that you stir the melt frequently to maintain consistency, at least ever 40-50 boolits.

Anyhow, just thought I would pass this on!
1Shirt!

[375RUGER]

That's good stuff right there.

[fredj338]

I have always pressure cast my LHP, it's one reason I have few issues w/ proper fillout of the HP or keeping the pin super hot. Smallest I go is 9mm though.

[johnly]

I'll join the choir. I've pressure cast from a bottom pour pot and from a large ladle and both work great. I think really big bullets come out better using the ladle as I can fill be mold quicker.

John

[Michael J. Spangler]

I have pressure cast with amazing results on HP other than holes in the bases. I need to perfect my method to ensure that doesn't happen. It's by far the best way to get fill out on hollow points in my humble experience.

[Shuz]

Another aid to getting uniform boolits from a bottom pour furnace, is to insure that the level of the melt stays between full and 3/4 full and that you float a 1/2" or so layer of (new) kitty litter on the top of your melt. This prevents oxidation of the alloy.

[1Shirt]

I agree with the fill factor, but I use half full as my measure and it seems to work ok. Have never tried kitty litter, and doubt I will try it as I am having success without it.
1Shirt!

[hickfu]

Another aid to getting uniform boolits from a bottom pour furnace, is to insure that the level of the melt stays between full and 3/4 full and that you float a 1/2" or so layer of (new) kitty litter on the top of your melt. This prevents oxidation of the alloy.

Hey Shuz, what brand kitty litter do you use? I want to do something about the oxidation and have been using sawdust but I cast indoors and the smoke gets real bad even with the fan going.

Doc

[eka]

Little 22s in my experience require exact weights for consistant accuracy, and due to the small amount of lead going into the mold requires that you develop a technique just for them.

Man some great stuff there 1Shirt. Is the technique you use for the 22's the pressure fill and then pull away for the small sprue? Same method for hollow point and standard boolits? Your post is great timing. I just ordered my first 22 mold and have learned from reading here already that it will come with a learning curve attached.
Thanks.
Keith

[Slow Elk 45/70]

Good post

[detox]

I also recommend that you stir the melt frequently to maintain consistency, at least ever 40-50 boolits.

Anyhow, just thought I would pass this on!
1Shirt!

Good tip. I also use a very small piece (pea size) of Vita-Flux before stiring.

I am not a believer in using saw dust or kitty litter as flux in bottom pour pots.

[JeffinNZ]

My Erik converted 225462 is a bit fussy and likes some pressure to get a good form. Either a full ladle held tight on the sprue plate or poured in its entirity and let run back into the pot.

[detox]

I have discovered that Linotype lead gives good fill without pressure casting. My Lyman #2 alloy fills less and more shrinkage.

[44man]

What is pressure casting? Molten lead is liquid and can't be compressed. All you do it squirt air out faster. A full pot is no different then a half pot, you CAN NOT MAKE LEAD DENSER WITH WEIGHT.
You need to understand that keeping the spout or ladle in contact just feeds molten lead to the boolit as it shrinks instead of it trying to suck from a sprue that is cooling makes a better boolit.

[Shuz]

Hey Shuz, what brand kitty litter do you use? I want to do something about the oxidation and have been using sawdust but I cast indoors and the smoke gets real bad even with the fan going.

Doc

I dunno what the actual brand is......but I got it at Wally World and it is a generic (prolly Equate brand!)unscented diatomaceous earth, which is nothing more than a form of clay. No smoke at all, as it is inert to lead alloys. It simply floats on top of the melt and prevents air from getting to the alloy and thus oxidizing it.