Bullets Sticking in Mould

[Trapper458]

Hi All,
I'm not new to casting but have some problems with my new RCBS mould. I bought the 85gr .258 cowboy mould for my 25-20. I cleaned it with brake cleaner and a toothbrush, brought it up to temp with the lead (hard linotype) and casted away. I get nice bullets but they stick like the dickens in the mould to the point I have to beat on the hinge pin with a big stick like a madman to get them to come out. I tried kroil, I tried smoking it with a match, no joy, still stick like crazy. Any ideas?
Regards,
Trapper

[462]

Under magnification and bright light, look for burrs along the edges of the cavities. Some casters use an eraser, to remove them, others nothing more than a finger or thumb nail.

Worse case is lapping, using a boolit and fine grit lapping/valve grinding compound. A search will turn up a couple of ways to go about it.

[HangFireW8]

I've had this problem with a couple of Lyman molds and several Lee molds.

In some cases, examination under a 10x lens showed tiny burrs, especially where the vent lines entered the cavity.

On one of the Lee's, it turned out to be casting flash under the sprue plate that was holding the boolits in place. In particular, the machined surface allowed tiny little fingers to radiate out from the boolit base and "hold on". Lapping the top of the mold and truing the sprue plate to sit tighter over the cavities fixed it.

In a couple of other cases, one Lee and one Lyman, I simply could not find anything wrong. On this Lee, boolits needed to be pried out. I was convinced that one side of the mold was cut 181 degrees and the other 179. I relieved the edge with a cratex on a dremel and that fixed it. On the Lyman, I relieved all mold edges with cratex and that fixed it.

Some may be appalled, but when it's either cratex or the trash can, it gets cratex, and I haven't ruined a mold yet.

EDIT: Oh yeah, and what 462 said, lapping. I now lap every time after I clear vent lines with a scribe. I know the scribe knocks burrs into the cavity, but I need to clear the vent lines (especially on flea bay specials), so I just assume the burrs are there and lap. 400 grit Clover for a minute or two doesn't hardly open up the mold, maybe .0001 (a ten-thousandths).

[theperfessor]

+1 to what 462 and HangFireW8 say. Lapping a troublesome mold isn't hard and almost always improves bullet drop. I'm convinced that a "well seasoned mold" is simply one that has been used enough to knock off the microburrs through repeated use, which can be a long and aggravating experience, or through judicious lapping, which only takes a few minutes.

I like the pour-through-a-hex-nut method that another member has posted about here.

[Bret4207]

The guys have it right on deburring and lapping. Another issue that may be contributing is your use of linotype. Linotype and other high Sn/Sb alloys tend to cast a bit larger than the alloys with higher lead content. A switch in alloys might help.

Personally I'd deburr it first.

[Calamity Jake]

What every one else says, burrs and lapp, plus let's hope that the cavities aren't off center to the blocks, if they are send it back to RCBS.

[Trapper458]

Thanks for all the input folks, I'll give deburring and lapping a try.
Regards,
Trapper

[gnoahhh]

I'll add that, at least with a couple of my molds, running the lead at a high temperature will cause some aggravation with sticking. Cutting back the heat 50deg or so cures it. (But then one particularly cantankerous mold- my favorite as luck would have it- doesn't produce well filled out bullets for some reason without running hotter than normal, with any alloy. I just live with it and get on with my life.)

[1Shirt]

In addition to previous recommendations, add a Kroil treatment. Works for me!
1Shirt!:coffee: