Fill-out problems...need advise

[ShooterAZ]

I'm having some problems with a mold. It is the RCBS 44cal 250K. This mold has a lot of very square profiles/edges and some boolits are not filling out well (rounded edges, not square). I have been culling any boolits that the front driving band has not been sized at all.

The mold has been well cleaned and used several times...I preheat it on a hotplate.The alloy I am using is 1 part linotype to 3 parts pure lead, so I think I have enough tin in there. I am casting at 675-700 degrees.

Is there some tricks to getting better fill out with molds of this type? More tin to the mix? Hotter? Cooler? I'm getting to many rejects.

Thanks...Shooter

[Larry Gibson]

Try 700 - 725 degrees.

If using a bottom pour pot keep the sprue plate 1/4" or so from the spout. Open the spout adjustment so the alloy comes out quicker. Pour alloy so there is a generous sprue, even if there is run off.

Larry Gibson

[Ronbo256]

Not enough Tin. By Bumpo682's excel spreadsheet 3 parts pure lead to 1 part linotype yields an alloy that is 96% lead, 3% Antimony, and 1% tin. A one to one mix would yield classic hardball, 92% lead, 6% antimony and 2% tin. PM me if you want a copy of the spreadsheet.

[5shotbfr]

i like just a bit more heat myself , around 750

it may be that just casting a bit faster will help keep those rounded edges at bay by keeping the mold temp hotter and more consistant , also keeping a cadence while casting helps a huge amount as well , i like to use a clock with a second hand to look at every now an then to make sure i keep doing everything the same way every pour

[Ronbo256]

Larry and 5shot bring up excellent points, I cast at around 725-750 myself, I missed that in your post. 1% tin should fill out if you follow their advice. I count one one thousand, two one thousand to 4, then break the sprue, cadence will help maintain an even mold temp which will help fillout.

[ShooterAZ]

Thanks guys, I will put the heat up to 725. And yes it is a bottom pour pot, so I will adjust to get a heavier stream as well. I was using a fast paced cadence...and waiting a few moments when boolits were getting very frosty.

[Le Loup Solitaire]

Short fat pistol bullets are easier to cast than long narrow rifle ones , but in either case you will get sharper and better filled out results with 1-2% tin. As pointed out you must get a sufficient flow of alloy, from a short distance of "drop", and have a gnerous sized sprue puddle to feed the cavities for shrinkage as the sprue cools. A gimmick that also can improve results is to pass the still molten sprue puddle under the nozzle a second to re-feed the puddle....its messy but with heavier bullets it seems to help, so its worth a try. LLS