RCBS 30-150-sp not filling properly

[djensen]

I am having a problem with one of my RCBS 2 cavity molds the rear cavity only is filling right about 25 to 30% of the time. I am using an RCBS Pro Melt and the lead seems to be stopping in the sprue plate. Sometimes the mold fills 30% full sometimes 98 % full. About every fouth bullet it fills properly. I have never had this problem before on any of my other molds. The bullets are not wrinkled the lead just seems to be having issues going through the sprue plate. Any suggestion will be appreciated

[Ben]

# 1 Do you have a strong steady stream of alloy coming from the spout without a mold in place ?

# 2 How tight is the sprue plate ?

# 3 As a trial , loosen the sprue bolt until you can easily move the sprue plate back and forth with your little finger.( cold mold ...not a hot one )

Try this and report back.

Ben

[.22-10-45]

1+ on what Phineas said. I have a few Ideal/Lyman moulds that need closest cavity filled first. I probably should examine vent lines .

[cbrick]

I think Ben nailed it. How full is your pot? Have you adjusted the stream coming out, is it a trickle or good flow? It is adjustable . . .

Rick

[detox]

Sometimes i have to loosen sprue plate so that it swings freely to get good base fillout...this vents base of mould better. You do not want it too loose, this will cause raised sprue plate cuts on base of bullet.

A sprue plate that is too cool will cause poor base fillout also. I preheat my entire mould using a propane torch.

Like someone else said ""adjust pot for higher flow maybe" and possibly turn up pot temp.

Lots of variables

[djensen]

Loosened the sprue plate, turned up the flow filled the cavities in random order. Both cavities filling proper. Tonights stack of bullets looks a lot nicer than last nights. Thanks to all for the help