RCBS 38-150 KT mold

[Lefty SRH]

I've been playing with a new (to me) RCBS mold. It maeks one nice .360" diameter boolit! BUT on both boolits (from both cavities) there are two little whiskers on the edge of the meplat. They are coming from the vent lines in the mold, I can see it when I open the mold before they drop out.

What can I do to the mold the eliminate the "whiskers"?

[blaser.306]

How hot are you casting? Are you adding tin to your alloy? Are you "pressure casting" with the mould against the spout of a bottom pour furnace or ladle ? If you answered yes to most of these questions , try letting the alloy flow onto the edge of the sprue cutter hole then into the mould cavity causing a bit of a (swirl) as the lead goes in. it may help with the "whiskers" that you are getting.

[fredj338]

I realy like that mold, one of my fav 357 bullets. Pressure casting usually causes the whiskers. Check to make sure the mold faces have no little bits of lead clinging to them.

[Ben]

I have taken a # 2 pencil and filled the " offending " vent lines with graphite , this helped but it did not usually totally stop the problem.

Some of the aerosol spray mold prep sprayed into the vent iines ( without getting any in the bullet cav. , just put a bullet into the cav. and spray it ) would probably do the trick also. While mold prep is wet, it might be a good idea to drag a single edge razor blade across the mold faces to keep any build up from occuring. You just want it in the " offending " vent lines if possible.

[rintinglen]

You are probably pressure filling the mold. Put a bit more daylight between the spout on the pot and the sprue plate, if you are bottom pouring, or a little less temperature if you are ladle casting. That should take care of the problem.

This is one of my personal favorites in 357 magnums, generally being more accurate than the Keith 358-429 IME, and you can crimp in the crimp groove, regardless of your cylinder length.

[DLCTEX]

That is a good shooting boolit in my 38 Sp. also.

[Lefty SRH]

No TIN added. Not pressure casting, good bit of day light between spout and plate. Alloy is about 700 but I have to move fast with this little mold or they don't fill out. The meplat is PERFECTLY aligned with a vent line. Other than that its a great little mold and good lookin boolit!

So what are your .357 mag recipes and what .38 recipes for this boolit?

[MtGun44]

For .357 Mag try 16.3 H110 and a mag primer. VERY accurate full power load for me.

5.0 Unique is a good, stout .38 Spl load in this boolit wt range.

Bill

[rintinglen]

Bill's loads are good, though in my Python, 15.7 grains of H-110 gives better accuracy, at a cost of slightly reduced velocities. 3.8 grains of Red Dot, 4.6 grains of WW-231 and 4.0 grains of Bullseye have all worked well for me in 38 Special cases when launched from various .357's.

[ChuckS1]

That mold makes me wish RCBS sold 4 cavity molds.

[skeettx]

Question
What mould handles are you using?
Sometime other brands of handles will not let the RCBS blocks
totally mate.

Mike

[codeNshoot]

I have far less experience then most board members here, but I think I have seen something like this. I ladle cast and pressure pour, for what its worth.

I recently bought a used RCBS mold that showed the same symptoms. There was lead on the mold faces, and lead in most of the vent lines running to the cavities. I cleaned the faces and vent lines, but there was still a gap in the cavities when closed. So, I then adjusted the alignment pins until i couldn't see light coming from the bottom of the mold through the cavities using a flashlight.


I did not cast with it as it was. When I did cast with it, I didn't end up with whiskers or lead on the mold face at all, and it drops fine bullets for me.

Check it with a flashlight, alignment pins can be one possible cause.

[Lefty SRH]

Question
What mould handles are you using?
Sometime other brands of handles will not let the RCBS blocks
totally mate.

Mike

RCBS handles.

[Lefty SRH]

I have far less experience then most board members here, but I think I have seen something like this. I ladle cast and pressure pour, for what its worth.

I recently bought a used RCBS mold that showed the same symptoms. There was lead on the mold faces, and lead in most of the vent lines running to the cavities. I cleaned the faces and vent lines, but there was still a gap in the cavities when closed. So, I then adjusted the alignment pins until i couldn't see light coming from the bottom of the mold through the cavities using a flashlight.


I did not cast with it as it was. When I did cast with it, I didn't end up with whiskers or lead on the mold face at all, and it drops fine bullets for me.

Check it with a flashlight, alignment pins can be one possible cause.

I had to adjust the alignment pins and now there is now gap but the poor ole boolits still have whiskers....I personally think they are more of an eye sore than a concern of accuracy. Someone please correct me if I'm wrong.

[Le Loup Solitaire]

As stated previously, whiskers often result from pressure casting. They used to be considered a sign of really good fill-out. J. Carmichael in one of his classic articles in "The Art of Bulletcasting" has several pictures of bullets with profuse whiskers and states that either rolling the bullets in a towel to remove them or running a stiff thumbnail along them to shave them off. A couple of them in the nose area is not a serious thing, but they should either be prevented or knocked off with the fingernail, as they look kind of sloppy and might interfere with nose or seating punches. LLS

[Lefty SRH]

I am definately NOT pressure casting.

[Hardcast416taylor]

That mold makes me wish RCBS sold 4 cavity molds.


Take a look at the NOE #358477 mold that is in the group buy site. It is scheduled to be cut about the end of March.Robert

[Iron Mike Golf]

Lefty,

Look at the vents under magnification. I am thinking they are bigger than they should be. Maybe from rusting in the past? Any signs of pitting?

If that's the case, then maybe periodic filling with mold release is the way to go. It'd be a pain to scrape each boolit. Those shouldn't affect accuracy. I would be mindful of seater plugs and top punches. Maybe use flat faced ones and disregard the whiskers?

Could you post a pic?

[Lefty SRH]

Lefty,

Look at the vents under magnification. I am thinking they are bigger than they should be. Maybe from rusting in the past? Any signs of pitting?

If that's the case, then maybe periodic filling with mold release is the way to go. It'd be a pain to scrape each boolit. Those shouldn't affect accuracy. I would be mindful of seater plugs and top punches. Maybe use flat faced ones and disregard the whiskers?

Could you post a pic?

I best I can tell the mold was brandnew when I got it and the previous owner IIRC said he never tried it. The vent lines do look TOO deep as comparing it to my RCBS 44-250-K mold.
I'd be happy to email you a pic if need be.