That's what I hear and I am still trying to figure out what the proper speed is. I have a grand total of 4 casting sessions under my belt and I tried Bull Shop's suggestion of about 4 cycles per minute.I find I do three and maybe squeeze a 4th one in and so far,I seem to be getting better results.Now I am wishing I could get sharper edges on my driving bands.Some are ok,some are rounded.I haven't quite got that down pat yet.Out of about a hundred bullets,I get maybe 30 that are ok.
A 1-2% of tin added to your alloy may solve the fill out problem. You may also reduce the melt temp (sprueplate cools quicker) with the tin addition. That would help reduce the cycle time.
While each mold is a mystery of it's own, keeping written records will keep you from having to re-invent the wheel every time you start to cast, or swap molds.
Bull Plate sprue lube works wonders, goes a loooong way, and is cheap.
Permatex AntiSeize works great as a sprue lube, and have never had any issues with lead build up on a mold.
As you are casting, if you ever have the sprue break or crumble when opening the plate you are going too fast. It should be solid. If you have lead in the holes of the sprue plate after removing the sprue plate you are going just a bit too fast. Every mold varies in this regard because sometimes you are using a 6 cavity where the bullet weighs more than 200 grains and other times you might have a 2 cavity where the bullet weighs less than a hundred, plus whatever your alloy is and the temperature at the moment can affect speed also.
For some applications it is necessary to pressure pour by putting the mold tight to the spout on the melting pot but to do this you have to slow the pour way down so you don't have alloy squirting out everywhere. This can be difficult because when the spout starts to get crud in it, the pour will slow down quickly where it causes a problem. Also some molds are not up to quality standards and will give you fins on the sides or a base that has extra on the back of the bullet with too much fillout. It will slow you down too until you get used to this action but no matter what, the speed of molding depends on how fast the sprue gets hard.
Most likely your mold still isn't completely clean and some aluminum molds can take a while before every bit of oil is out of them where you will get good bullets. Likely some of your cavities are giving you good bullets where others aren't and a good scrubbing with soap and water, boiled, spray brake cleaner, or mineral spirits with a tooth brush will help but sometimes an aluminum mold just takes time to get clean.
Well,I took some advice here. I used a a small dab of Bullplate on a q-tip ,according to Bullshop's instructions and applied it to the bottom of the sprue plate and top of the mould.I had my carpenter's pencil at the ready and commenced to cast bullets.It happened,I eventually had to simply apply the pencil to some smears while the mould was still hot and off they came,no fuss,no muss.
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |