New rifle mold and too many cull boolits. . .

[OFFSHORE]

I recently started casting for the 358 Win. and until this time never cased anything smaller than .401 diameter bullets (not that that matters I guess). This particular mold from Accurate Molds is the 36-240K, and I use a 30:1 alloy of COWW/Pewter. The mold is a steel mold, 3-hole, I get best looking bullets at 700 degrees, and I ladle cast them. I'm getting bullet weights from 233.XX to 237.XX and do not know why! When I cast a pile of bullets I pick 31 at random and then weigh each one to come up with an average, then I allow a half a grain on either side of the target weight for culling. . .in this particular batch the target weight is 235.8gr., so anything a half grain +/- of that goes back into the pot. My culling has me at about 60/40 in favor of good bullets. . .is there something I'm missing or should be doing to have lesser culls??? I've never experienced this high of a volume that is what has me scratching my head. Thanks for any advice.

[MT Gianni]

I have had good luck with accurate molds but my first step would be to segregate by cavity. You might have to cast one cavity at a time to do so.

[WRideout]

I have had times when the sprue cutter is not quite flat, and it will create uneven bases (and perhaps different weights.) Also, If I don't pour a big enough puddle, it will not fill out completely, and sometimes leave a dimple in the middle of the base.

Wayne

[Winger Ed.]

I don't even own a thermometer for casting.

I run the heat up until I get a mild bit of frosting on well filled out boolits, then back off the heat just a little
until there is no sprue shrink hole or frosting.
I'll reject the first dozen or so from my two hole molds, then rock along until I get tired of sitting there.
Even with being real particular about .30 cal rifle boolits, my reject rate is very minimal.
It isn't a perfect method, but it's worked real well for me since the 80s.

[country gent]

I to would start by segregating the cavities and see the spread in each cavity before going farther. If this is a new mould I would also give it a couple sessions to break in.
Once you have the segregated bullets you can start measuring Here dias lengths width of lube grooves, to see if there are any variations in the cavities. Also if the 3 cavities are good to themselves there is the old practice of marking the cavities and segregating them. Leave one cavity blank, one cavity a point and one an X.

[mehavey]

- You do need a lead thermometer
- You do need to cast 30:1 hotter, at about 780°
- You do need to pre-heat for uniformity (https://thefiringline.com/forums/showpost.php?p=6814751&postcount=16)

Tom's moulds will cast very consistently thereafter.

[243winxb]

Post #4 is my method.

No preheat needed. Cast till you get good bullets.

Bottom pour pot - try pressure casting.

[OFFSHORE]

Thanks everyone. I have segregated the cavities and haven't been able to pin down any one over the other yet. My bullets look great all the way around and I always preheat my molds by setting them on my furnace for a bit and then running about 10 sets through them. I have close to a dozen of Tom's molds, all steel and all .401" or larger. . .never had any issue, just as smooth going as can be. I will check my sprue plate and try bumping my heat a bit to see where I end up. Thanks again for the tips.

[gwpercle]

The mould might just need a longer break in period . Usually with a new mould , and I pressure cast with a Lyman spouted dipper , it takes at least 6 nice casting sessions before I'm satisfied the mould in broken-in and developed a seasoned finish in the cavities . If after this amount of casting ... it's still dropping too many rejects then it's time to look at other causes .
I only keep those with no visible defects and are completely filled out and sharp .
Also nothing wrong with casting on the hot side ... just below or right at frosty ... no visible defects and I call them keepers ... I stopped weighing them unless shooting for money or prizes !
Gary

[popper]

4/235=1.7% and no target really cares.

[Winger Ed.]

4/235=1.7% and no target really cares.

I'm not so sure bro.
If you don't put a killing hit on 'em, they'll drag off their wounded, and patch 'em up to taunt you another day.

[OFFSHORE]

I'm purely a hunter and practice session shooter, although I'm sure I have A LOT more money on the table in my hunting hobby than some shooters - LOL! I'll keep at it and raise my temp up a bit to see where it leads me. Tell me. . .what do you consider a "casting session"? Like I said, this is a new mold and the smallest bullet diameter I've ever casted for, and my first "session" was with about 30 lbs. worth of alloy. Again, thank you for the tips.

[Winger Ed.]

. .what do you consider a "casting session"? .

For me a couple of things determine the length of one.
I have a decent stash of boolits made up, so there's never any pressure to make some.

1. I'll rock along until I get tired or my back starts to hurt. Those usually last about 2-3 hours.

2. The other is when the wife wants me to do some actual work.
Then I'll disappear out into the shop until she forgets about it. Those sessions often take longer.

[GregLaROCHE]

I don't even own a thermometer for casting.

I run the heat up until I get a mild bit of frosting on well filled out boolits, then back off the heat just a little
until there is no sprue shrink hole or frosting.
I'll reject the first dozen or so from my two hole molds, then rock along until I get tired of sitting there.
Even with being real particular about .30 cal rifle boolits, my reject rate is very minimal.
It isn't a perfect method, but it's worked real well for me since the 80s.

I do the same thing.

[Land Owner]

You never know until you try. After visual culling, you may be using a single data point, boolit weight, to reject unknown potential. If they "look good" why not shoot some high plus and some low minus boolits. You might be surprised. Let the rifle/round combination, your confidence and skill too, tell you on paper out to say, 200 yards, which is the best boolit weight for your case, primer, powder, and barrel. It is ALL Learning Curve anyway.

[tmanbuckhunter]

Temperature variation, pressure on the mold handles, cadence, flow rate, all can vary bullet weight by a large margin, especially if you're using an aluminum mold. It's an experience thing, and the more you do it, the better you will get.