Whiskers - how to stop'em?

[BrentD]

So, I'm watching the late football game and patiently scraping whiskers off of 200 180gr bullets from a new RCBS mould for my 38-40. These are grease-groove bullets (gasp!) that will be launched from my new-old Marlin 1894. These are cast out of 40:1 alloy.

I have heard before that RCBS moulds have a history of being bad for whiskers. I had one custom mould cut in an RCBS mould and it whiskered like mad. Now this one is doing it. It is a two cavity mould - brand new - carefully cleaned and heated, and w/o any light visible between the blocks when closed. I run my alloy at about 780F but with these whiskers being so extreme, I tried lower temps down to something below 700 and all I got for my trouble was bad bullets with unfilled bases and whiskers.

The whiskers can be over 0.1" long. One cavity whiskers worse than the other.

Are there any solutions to this besides having a new mould made? This bullet has come highly recommended by a couple of notable competitors who have a lot of experience with it (and yes, I'll be asking them about how to deal with whiskers).

Any suggestions on how to fix this would be very welcome.

Thanks.

[earlmck]

I'm assuming you're using a bottom-pour pot? Using direct contact with the mold? If so, try holding the mold below the spout a bit, a fairly slow stream of metal flowing. You'll likely have more failures to fill out the base real well but should lessen the whiskers. I have a couple of Lyman molds that whisker bad if I use contact with the spout, so it isn't just RCBS.

Another thing, maybe use a few applications of the spray-graphite like Midway sells, clean off the faces between applications but let it build up in the vents -- might inhibit the flow down those vent lines a bit.

[J35]

RCBS has about the best customer service out there.

Send that puppy back, no need to put up with that.

I have a ammo can full of RCBS molds and they don't whisker.

I bought a new 30 cal 150gr CB mold and the bullet nose on both cavities ended in a vent groove, sent it back and had a new mold in ten days, coast to coast.

I have picked up used and abused RCBS molds at gun shows, called RCBS and tried to buy new sprue plates, they sent me new ones on their dime .

---J

[BrentD]

Earl,
I am ladle casting. I'll see if I can imitate your suggestion for bottom pours though. In other moulds and bigger bullets (.500+ gr .45s) I have never done well if the ladle wasn't pressed closely to the sprue plate. But I'll give it a try.

J35nut - I like your suggestion too. I'll send RCBS a note and see what they say.

Thanks,
Brent

[Sixgun]

Brent,
Earl has it right. The only time I have ever had whiskers is when either the mould was not closed properly or if there is too much force of the lead going into the mould. If you are ladle casting, don't fill the ladle up.
--------------6

[Rusty]

Try a little pressure on the mould handles while you're filling. Not enough to turn your knuckles white mind you, just a little.

[BrentD]

Rusty,
I have pressure on the handle - and even white knuckling won't help. I have also "set" the blocks together with a light tap of a stick to the back of handle jaws. The blocks are well mated, no trash in between.

I just sent a request for help to RCBS and I'll see what they have to say too. Very frustrating. I spent 2x longer shaving the whiskers with an exacto knife last night than I did casting them yesterday morning.

[Don McDowell]

Same as I suggested on bpcr.net, with one more addition, if you still have those locking mould handles that Gussy makes, might try those.

[Sixgun]

That is really strange. In working with at least 200 moulds in my lifetime, the only way whiskers formed by by too much of a force of lead, not closing the handles properly, or a warped mould, which only happened once on a thin single cavity aluminum mould.

Take a measurement of the completed bullet. If its much more than say, .002 over standard groove diameter, you might just have a mould that is concave where the bullet "hole" is, you know, dished out, so it may look good to you when it is closed, but it may not be on the inside.

Compare the vent lines to a proven mould. Somebody might have been generous with the vent lines.-------------6

[Griff]

Sounds like a defective mold. Send it back.

[BrentD]

Don, I could give that handle a try. But I don't see why it would work since, even if my grip isn't consistent, the whiskers certainly are. Nothing I did with my grip influenced them at all. But holding the ladle off the sprue plate is a novel idea that I will try. When I do that with my other moulds, I generally get rounded edges to my bullets' bases. Still worth a try.

I'll also be interested to see what RCBS says. If I don't get anywhere there, I'll try the Midway spray graphite - interesting idea to be sure. And then maybe stoning and then maybe me standby solution to everything - Steve Brooks.

[Don McDowell]

Brent that should work for you, it did for me. Two of the rcbs moulds I have are prone to the whiskers. The other two will on occasion but not as bad.
Yes Steve is never a bad choice, also don't overlook Accurate moulds he's got some good designs, and his prices are pretty good.

[Don McDowell]

Brent one other thing, I generally cast those bullets from 20-1 or straight wheelweights.

[Chuck 100 yd]

If the dowel pins are too tight it requires excess force to keep the blocks closed tight and you will make whiskers. I take a tapered reamer and (by hand) carefully remove a tiny amount of metal from the inside of the dowel holes in the block that don`t have the dowels mounted in it. RCBS molds are made on the tight side and are one of my favorite molds. I prefer the larger blocks over Lyman`s but usually prefer Lyman`s bullet designs.