GTA
All Springer/NP/PCP Air Gun Discussion General => Projectiles => Boolit and Pellet Casting => Topic started by: Spacebus on April 05, 2022, 05:13:00 PM
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Before picking up the Lee today my previous casting experience was with using a wood fired "rocket stove" which didn't work well for me. It was much too hot and I ruined a .22 cal pellet mold, but I got lucky and my .457 BBT is in good shape. Using the Lee was a much better experience and I had very few culls with much more consistent weights. I think a bottom pour would be nice for my .45 bbt mold, but I get great results using the "pressure casting" technique from Wayne's sticky thread. After 100-ish BBT's I moved on to the NOE 250-22-WC and very few culls as well. In total I got 75 .45 BBT HP 222 grain slugs that are all +/- 1.5 grain and 324 .25 22 grain WC's that are all +/- .5 grain.
I also have a hot plate for using my aluminum pressure canner, but it doesn't get quite hot enough for lead. it worked amazing for casting in pure tin, so I'll keep using it for that so I don't get any lead contamination. I have some .250-41-FN cast in pure tin, but haven't had a chance to test accuracy yet. My compressor died, so I'll have to wait to test the .45 BBT's until this weekend, but they shot well when cast with wood fire. The .25 WC's are for a build awaiting parts, so that will be a while as well. When I get some more o-rings for my Eagle Claw I can test the tin slugs, but I'm not hopeful. There is another 217-19-RF mold on the way along with a 250-34-RF which I hope will do better in tin. If they don't, I'll be giving up on casting my own lead free ammo and use Predator GTO's for garden vermin.
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Your hot plate can be used to warm molds (assuming you can turn it down to around 400-450 freedom degrees), so not a lost cause at all. Good for if you need to take a break or add lead to the pot. I get better results heating my molds on a hot plate than trying to warm them over the lead pot, normally now I can get good castings within the first 2 or 3 attempts, some even on first pour but as habit I toss those out.
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Your hot plate can be used to warm molds (assuming you can turn it down to around 400-450 freedom degrees), so not a lost cause at all. Good for if you need to take a break or add lead to the pot. I get better results heating my molds on a hot plate than trying to warm them over the lead pot, normally now I can get good castings within the first 2 or 3 attempts, some even on first pour but as habit I toss those out.
I have to get a power strip first, but that is a good idea. Today I did not pre-warm the mold beyond resting it against the side of the pot when not in use. Instead I just threw the first few pours back in the pot and then I was getting good fill with minimal if any wrinkles. I had the pot up to 725-750 and that was giving me great .25 cal wadcutters without any wrinkles and wish I had the pot that high for the .45 BBT's. I think my mold could also have been a bit hotter, but I wasn't taking any chances. Perhaps future mold orders will be drilled for a probe.
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I had one drilled and they got into the steel mold handle pin. Now I know how it's done I dont know if I will have it done again.
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I had one drilled and they got into the steel mold handle pin. Now I know how it's done I dont know if I will have it done again.
Perhaps it's not worth it then. Maybe setting my IR thermo emissivity to aluminum would be easier.
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If you throw the rejects and sprues back in the pot, it pulls a lot of heat out of the molten lead. Get a thermometer and watch what happens. Rejects and sprues go into another container until I'm ready for a pause, then I'll dump them back in and take a break.
I mention this because I was cutting sprues directly back into the pot and wondered why stuff was getting wrinkles after a few pours. Then I got the thermometer and figured out what was happening, it is surprising how much heat gets stolen buy just the sprues and how slow the recovery time is with my 4-20 pot. Would probably be better with a PID control, but don't have that yet.
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If you throw the rejects and sprues back in the pot, it pulls a lot of heat out of the molten lead. Get a thermometer and watch what happens. Rejects and sprues go into another container until I'm ready for a pause, then I'll dump them back in and take a break.
I mention this because I was cutting sprues directly back into the pot and wondered why stuff was getting wrinkles after a few pours. Then I got the thermometer and figured out what was happening, it is surprising how much heat gets stolen buy just the sprues and how slow the recovery time is with my 4-20 pot. Would probably be better with a PID control, but don't have that yet.
I take a break when I toss in sprues and culls and let the pot come back up to 650f+ and then flux with borax. After I scrape out the dross/slag I have to put the lyman bottom pour ladle back in the pot for a while to get it back up to temp as well. I could probably run the mold and pot hotter, but I'm taking it in baby steps. The .45 cal BBT mold would benefit from a bottom pour melting pot, but it would be hard for me to justify that cost just for the one mold. I feel like a bottom pour pot would be tough for pellet molds with tiny cavities.
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After wasting a ton of my tin .25 cal BBTs yesterday I figured out my barrel grub screw was loose and today I put my red dot on the Eagle Claw and tried to make groups with the tin slugs, and they did ok! At 25 yards with a red dot and shooting stick I was making a 1.5" group, which is not terrible in my opinion. I'm waiting on a new chrono, but the same slug weight in lead was giving me about 900 FPS, so I'm hovering around 50 FPE. I suspect the groups would be a bit tighter, albeit not "match grade", with a good rest and scope. Good enough for dealing with vermin around the homestead.
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Space bus check out cast boolits and Los angels silhouette club sites
Great info for casting.
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Just made 286 pure lead NOE 250-41-FN BBT slugs, all within .02 gram as measured by my scale. Only had a dozen or so culls and I think those were when the mold was still cold. They work well in pure tin, or at least well enough for 25 yard pest control, but I am expecting even better accuracy in lead.