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j23
12-08-2010, 06:28 PM
I've been at this, going on two years now.. and I have amassed a small collection of molds, one Lee 45-255-RF 2-banger (ugh.., I hear the 6 bangers are vastly superior, lord I hope) and several Lyman molds. I picked up an RCBS 25-85-CM for my 25-20 last year... and cast with it a few times.

Is it just me, is it the small diameter bullet (my next largest is a 31141,) or is it that RCBS molds are kind of a pain in the rump to cast with?? It seems as if I can NEVER get it hot enough, and the two cavities are always a vastly different temperature? The front cavity, after I cast 200 bullets or leave the thing on the stove till its red hot, starts to drop a few good ones. The rear cavity is all but useless, the bullets are always incompletely filled or have rounded edges at best. I have YET to see a frosted bullet from this mold.

I just decided to cast up some 25's, because I'm out, and I want to hit some late season small game this year, and for the first time I cast in my Kitchen on my gas oven.. yeah, I know, I know, it's a no-no. But it's 26 degrees outside, I don't have a garage and WOW, is it convenient and cozy casting in the house!!! I left some kitchen windows open and from the drop in temperature in here, I got some fresh air. At any rate, even after casting on the stove, under IDEAL conditions for almost an hour, and laying out like 100 boolits, I have 12. Count'em, twelve bullets. The ones from the rear cavity, I just dumped back in the pot by default, it's obvious when I open the sprew that they aren't even close. The problem with most of the front ones are that most have like.. rounded features; like the mold isn't getting hot enough.

If it were just this mold, i would say that it's me.. but after casting with like seven(?) other Lyman molds.. .which are for all intensive purposes, the same thing, and always getting great bullets after warm-up, Im starting to think it's either THIS mold, or are RCBS mold's hard to manage?

canyon-ghost
12-08-2010, 06:35 PM
It is, get this, the small sprue plate holes that you pour through. Get it hotter, use some tin, and sort. Took me quite a while to notice what the real culprit is. I wondered why a Lyman looks the same and pours better. It the spue plate.

Now, look at the big alignment pins on an RCBS, and the little ones on a Lyman. You tell me.

Ron

RobS
12-08-2010, 06:39 PM
What is your alloy temp at? It sounds like to me that you don't have your mold up to temp for it to cast its best. With the smaller bullet cavities there is less alloy sitting in your mold so the mold will naturally run cooler if your casting tempo is the same as your large caliber molds; less heat transfer from the alloy since there is less alloy running into the mold.

There is also the possiblity that the mold is not venting well, but I've yet to see this with a RCBS block and most of the time they vent so well you'll get wiskers from the vent lines if the mold becomes too hot and/or there is good alloy flow going into the mold.

MT Gianni
12-08-2010, 07:27 PM
I own 4 RCBS molds that cast like a dream with a bottom pour from 625F-700F, I have one that has to have a ladle and 750F minimum. It is neither the smallest diamater nor the largest, and in the middle of the weight range. Take good notes and lets your molds tell you what they like.

bamacisa
12-10-2010, 09:56 PM
All my RCBS molds work great....no problems at all.