one cavity sticking

[HVACscott]

i have MP, 8 cavity, 9mm, 115 gr, one lube groove, beveled base, aluminum mold. made about 2000 bullets so far and now cavity 2 from sprue end is sticking really bad. any suggestion's?

[Winger Ed.]

Sometimes they just do that.
And it'll sort of come and go too.

I'd just clean it well, and make sure there isn't a burr in there somewhere.
As soft as Alum. is, I wouldn't get violent with it.
I had a 6 cavity Lee do some of that, I polished it by rubbing the open side of the mold on my blue jeans leg.

[Bazoo]

You can take a pencil and use the lead to press moderately firm against the cavity edges on each half and it will smooth down any small burrs.

[waksupi]

Take some 0000 steel wool, and go over the edge of the cavity. It will show you if you have a snag somewhere. Don't be overly aggressive, but you can safely work a mold over with that.

[RedHawk357Mag]

I have a custom brass mold that has this issue. I have tried burnishing with number 2 pencils, wooden tooth picks and haven't completely worked the issue out. I tried hand spinning a couple bullets with either Bar Keepers friend, semichrome, or Flitz's. Don't remember which it was now. That got me close to a workable solution. Definitely annoying, and definitely work gently and check progress often.

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[DHDeal]

I've had this happen with aluminum molds occasionally. I'll notice something "change" and one particular cavity will get sticky. It's usually after I've been casting for a while. If it continues I'll go up on alloy temp and while waiting for that, I'll look at the mold under a magnifier for any obvious causes. Even though the mold is hot, I'll use a carpenters pencil a chase the parting lines and grooves. Though I rarely smoke a mold, if the sticky cavity won't act right I'll smoke it lighly. Usually changing the alloy temp a little will help get back to where I want to be.

Oddly I've not had a sticky cavity with a brass mold. An issue I've had with MP brass molds would be the pins will not want to turn loose without another tap with the leather mallet. A touch of lube on the pin tips and away I go again.

[joebaja]

I've noticed the same effect on several aluminum molds, always in that second from the end position. It usually starts right about when the mold hits what seems to be the ideal temp for the other 5 cavities. Tried burnishing with limited success. What I usually end up doing is calling it a 5 1/4 cavity mold for the rest of the session. Pour into the other 5 until the sticky one lets go, so I don't interrupt the cadence trying to shake the oddball loose. Usually 3 or 4 cycles and it releases.