Buttons

[BulletFactory]

Didn't know what to call this thread, or if it should go into mold maintenance, but here goes.

I keep getting these "buttons" in the center of the base of the bullets. It seems the sprue plate doesn't always cut the bottom off flat, and leaves a bump. I'm using an Accurate mold, which is still very new. The sprue plate isn't loose, I keep an eye on it. Also, all to often, the mold will almost fill up leaving a rounded perimeter on the base instead of the sharp edge that it should be. Dont know how to fix this.

[LAH]

Don't know if this will help but if you cut the sprue with a stick/hammer/handle try to strike the sprue cutter at an angle toward the mould blocks. Or if you can cut the sprue while it's soft enough to cut by hand this may cure your problem.

[skeet1]

I have had this same problem, but it stopped when I started using a gloved hand to open the sprue plate instead of a mallet. When you open the the plate you can hold it down against the mould and get a smooth surface.

Ken

[onondaga]

The "Button" thing is why I am beginning to try the gloved hand trick too after casting since 1957! The glove does control the problem if you change your timing a little. Hand opening a little earlier than you would tap while the alloy is softer and then leaving the sprue plate open with the mold still closed for a 5 count has been working for me before I open the mold..

If you get everything just right when tapping it will work fine too. That involves trying different tensions on the sprue plate pivot pin and getting the angle of strike in exactly the same plane of the sprue plate. Hitting the plate on an angle will bounce it, causing lift during the cut and give you the buttons you refer to. A pivot pin that is either too tight or too loose will magnify the problem of a bouncing cut of the sprue when you have your tap of the plate out of plane with the plate.

That little button changes the stopping place of gas checks and then changes bullet length because of that. Of course, the button also affects bullet weight. It is something I want to get better control of too.I am playing with it.

Gary

[MtGun44]

Depending on the size, it is usually not much of an issue. Cutting when the lead is softer,
which works better without smearing lead on the sprue plate or mold top if you use Bull plate
lube, also helps.

Bill

[Doc Highwall]

Several thing can cause the bump to be larger. The cutting edge of the sprue hole has to be sharp and if you do sharpen it MAKE SURE YOU STONE THE BOTTOM TO REMOVE BURRS THAT CAN SCRATCH THE TOP OF THE MOULD. A sprue plate that is too loose and not applying downward pressure when cutting the sprue. I only use a gloved hand and squeeze the sprue plate down onto the top of the mould while twisting the sprue plate and get excellent bases. The importance of having the mould preheated when first starting cannot be skipped it allows you to use your gloved hand right away to cut the sprue. I wait for the sprue to change surface sheen/harden and give a 5 second count before cutting and after the bullet is removed from the mould I slowly and carefully close the mould with my right hand while holding the mould handles with my left hand.

[Charlie Two Tracks]

The bottom of the base not filling out correctly....... been there and done that. What is recommended is to see if your alloy is hot enough and if your mold is hot enough. I believe that the sprue plate can be too tight and cause this also. On one of my molds, the only way I can get it to fill out completely is to hold the mold right up against the bottom of the bottom pour and pressure cast them. I really don't know why this mold is like this but it is.

[BulletFactory]

I do preheat the molds in one of those little electric pans. I was mostly worried about bullet weight and consistency. Have not been shooting because the barrel needs work done so it won't lead, so I've been trying to work out other "bugs" like this one instead. I'll try the glove method and see what happens, but I like the little mallet that I've gotten used to. Its the small Lyman one with the interchangeable heads. I use the brass head to knock the sprue plate open, but I'm very careful about striking the plate square with the blocks, so as not to damage the pin or the blocks. Then I can whack the bolt to knock the bullets out when necessary. I keep the mallet in my hand the whole casting session, no need to pick it up and put it down.

[XWrench3]

Check the hole in the sprue plate. I have had one that was not cut all the way to the bottom, and it made a mess of the end ouf the boolit. I cut it deeper with a countersink my brother has in the drill press. As far as the rounded edges, check the top few vent lines. There is a better than average chance that one or more of them are plugged. The other most likely thing is you may need more heat in your alloy to get propper fill out.

[LAH]

I'll try the glove method and see what happens, but I like the little mallet that I've gotten used to. Its the small Lyman one with the interchangeable heads. I use the brass head to knock the sprue plate open, but I'm very careful about striking the plate square with the blocks, so as not to damage the pin or the blocks. Then I can whack the bolt to knock the bullets out when necessary. I keep the mallet in my hand the whole casting session, no need to pick it up and put it down.

I normally cast with 3 each 4 cavity moulds. These moulds have swinging sprue plates. That means I need not close the sprue plates with my hand. I simply tilt the mould to the left & the sprue plate closes it's self.

Since you like using the mallet strike the cutter at a slight downward angle instead of plumb to the mould face. I can only speak for myself the my cutters don't "bounce" but cut the base of the bullet square. Another plus is the loose sprue plate allows the base of the bullets to fill better. Hope this helps.