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All Springer/NP/PCP Air Gun Discussion General => Projectiles => Boolit and Pellet Casting => Topic started by: Steelhead on March 14, 2019, 08:37:40 PM
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Being a newbie to casting I'm learning a few things that I didn't know before or had assumed. I'm starting to get better at knowing temperature, lead behavior, flow rate, etc. and it's showing on my finished product. What I'm surprised about is the variance in weight. It doesn't matter what size/brand mould I use, I get a big range.
I'm currently weighing every bullet I cast. It's extremely tedious, but I look at it as a meditation time, not a chore. Taking the three bullets that I'm currently using, I'm seeing as much as 3 grains difference commonly on the larger 134 and 150 gr. bullets and 2 grains difference on the 133 gr. That's not counting the really over/under ones. In the process of weighing I narrowed down a middle ground that seems to be the majority (133.6 to 134.5, 152.5 to 153.5, and 116.5 to 117.5) It should be noted that I had a lot of bullets that were way out; maybe one in twelve. Shooting at 200 yards with one bullet weighing 114.1 and one bullet weighing 118.5 HAS to make a difference.
This is all very educational. For me I want to eliminate as many variables as I can. In the grand scheme of things, this is an easy one. The whole point of casting big bore ammo to me is making a better product than I can buy at a reasonable cost.
One little thing I'm finding is that some of my 150 gr. bullets have a 'foot' on them from the sprue hole. It's rough and sometimes a little irregular bump making the bullet 'stand crooked'. What causes this? It's annoying the heck out of me.
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Timing of the sprue cut perhaps, other than that how clean / sharp is your sprue plate hole ?
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My guess is that it's a timing issue because most are good. Could swinging the sprue too soon cause soft lead to 'push up' and leave a small bump?
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My guess is that it's a timing issue because most are good. Could swinging the sprue too soon cause soft lead to 'push up' and leave a small bump?
Yes, and make sure the sprue plate screws are adjusted so you have a fairly snug fit to the mold top. If not the cutting clearance is opening up and causing a poor quality cut.
On weight variance mold and melt temp control are important.
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It's all about the cadence. Steel and brass molds are far more forgiving than aluminium. I prefer them as it allows more breaks to have a smoke, drink some coffee. Sprue cut timing needs to be more precise the smaller the slug/pellet. Smear is too soon/hot and too cold will squish out of round. The .22 pellet mold has a 2 second window of too hot or cold to cut sprue- if that. Casting those is almost a chore.
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I pour with a hooded ladle directly into the sprue plate, I only get small nodules of lead to sheer rather than a big puddle. I only cast .22's and .25's so immediately after I fill all the cavities I'll cut the sprue's and have really great luck getting all my pellets really close to each other in weight. I use brass molds if possible, but I do it the same way with the aluminum molds as well. Pure lead is all I use though for pellets. I do it the same way with my muzzle loader bullets as well, I've been doing it this way for many years. I fully understand how a hard alloy would make a much bigger difference though. If I was going to go with anything other than pure lead I'd add some tin probably for larger calibers for airguns.
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Kevin, being a newb myself I know better than to give advice. I can say that I am right there with you in trying to figure all of this casting stuff out.
My first cast run yielded quite a variance in bullet weights (about a 4gr difference). From that experience, I figured out there is a sweet spot in temps for better consistency. I now use the NOE electronic thermometer to monitor my mould temp, or to get it up to temp before I start casting. Also, recently I built a DIY PID controller to precisely control the Lee pot temp.
I use a 4-cavity aluminum HP mould. In my opinion it is temperamental. I sometimes have to fight with getting the bullets to drop off of the pins. I now use a little spru lube on the HP pin tips, which helps out a lot.
My last cast yielded nearly all bullets within 1gr of each other. There were a small percentage of those outside of that range, but not many. I would like to think that with adjusting the PID set temp to dial in the bullet weight I set a goal for, I was successful. I'll have to cast more to know this was the reason to say for sure, and not just the mould finally reaching the temp needed.
One thing for sure, for me at least, is that this challenge in figuring out how to get perfect bullets and weights is a lot of fun.
Happy casting.
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Keith the really nice thing about casting your own is the fact that the molds eventually pay for themselves, especially if you do a lot of shooting and chrony work with them.
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Keith the really nice thing about casting your own is the fact that the molds eventually pay for themselves, especially if you do a lot of shooting and chrony work with them.
That's true, and I have been shooting a lot, and I lot more often knowing I can make quite a few more in just one casting session. I also like being able to recover and recycle some of the lead to also cut cost. More so though is dialing in the bullet to match the barrel.
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I'm really glad that the weather is warming up again, smelting pellets has to be done out doors for all the smoke. I know that when I put wax in the pot I just have to walk away for a while before being near the pot because that smoke is nasty stuff, heck my cigarettes are bad enough but the wax fumes will take away your breath fast and probably bad for coating the inside of your lungs. Actual fumes from lead start when the lead is 1000 degrees and the pot that I have won't get near that temperature. I melted a bunch this morning using lead that I first smelted out doors from recovered pellets. I probably cast 400 of the .22 hunters today.
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I plan on getting a bunch done before the heat and mosquitoes arrive, but maybe the mosquitoes wont like the smoke. I know I avoid it.
Before my PID controller, the beeswax I use would ignite and burn up quickly. Now that I have the temps more under control, the wax smokes a lot more with no ignition. I just picked up some paraffin wax to try.
I'll be receiving 20lbs of sheet lead from someone next week to process. Do you think I need to add any tin to it for the .357 slugs? I am trying to stay in the middle on my cast weights. I am sure the pure lead will raise the bullet weight some. I currently use 1:40 from Rotometals.
After a day of casting fun, I have more fun at night sorting the casts and playing around with making my sorting spreadsheet even better.
I basically weigh them out while inputting the last two digit weights into the spreadsheet, and lay them in two rows of 25 each. From there the spreadsheet takes over with most all of the processing being automated. The end result of the spreadsheet processing lets me know which ones and where to cull from out of the two rows for my desired spread goal. It's a pretty simple and fast way to sort them out, plus I have a record I can keep of the cast with details about the cast particulars.
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Trigger, I've got a bunch of BHN 10 lead if you want to bring the sheets up to 40:1. Melt it 50/50 and that's what you'll get. PM me if you're interested.
For that matter you can mix it 33 to 66 to end up with an alloy just over 1.5% tin.
A word of caution on sheet lead- I've source lead from many places and want to warn you on telephone pole jackets. Often sold as sheet lead but contains antimony and is actually same (or near) clip on wheel weights. If you have a No 6 (even a No 5) lead pencil use that to confirm pure sheet lead or if an alloy. If harder than either of those two pencils don't use it. Will have antimony in it.
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Trigger, I've got a bunch of BHN 10 lead if you want to bring the sheets up to 40:1. Melt it 50/50 and that's what you'll get. PM me if you're interested.
For that matter you can mix it 33 to 66 to end up with an alloy just over 1.5% tin.
A word of caution on sheet lead- I've source lead from many places and want to warn you on telephone pole jackets. Often sold as sheet lead but contains antimony and is actually same (or near) clip on wheel weights. If you have a No 6 (even a No 5) lead pencil use that to confirm pure sheet lead or if an alloy. If harder than either of those two pencils don't use it. Will have antimony in it.
Thanks! Yes, I would be interested. let me get my hands on it and see what it actually is first. All I know right now is sheet lead. I'll have my hands on it coming up soon.
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Thanks to all of you for the tips and advice. I did a session this morning with the Lee's 150 FNGC and saw a huge improvement. My weights were slightly more consistent and I had zero issues with the 'smear' or 'foot' problems I was having. Waiting a few extra seconds before swinging the sprue took care of that.
I ended up keeping about 2/3's of the bullets in the weight range of 153.2 to 153.8. All others went into recycling. It should be noted that I had two that were 159 and 4 or 5 that were 149. No difference in physical appearance.
For that reason alone I will continue to keep weighing/sorting. It's making me better at casting and I can't stand the thought of missing a shot in the field because of something that easily controlled. It's also due to the fact that I have a single shot gun and by nature I'm not going through a ton of ammo. Even with hours long range sessions I'm usually under a hundred. If I was casting pellets, forget it! The other big thing is that it's increased my confidence in leaps and bounds. I know I have the best possible, proven bullets and that just makes me feel that wherever I put the crosshairs is where it's going. The bullet will do it's job as long as I do mine. That's a valuable tool.