Faint vent lines on RCBS 35-180-SILH

[Marlin Junky]

I was getting some molds ready for an upcoming casting session and noticed how the vent lines on my brand new RCBS 35-180-SILH are mere scratches compared to those on my RCBS 35-200-FN. When the 35-200-FN is turned sideways and put in front of a light source, light can be seen through the mold in the shank area which is not the case with the new 35-180-SILH. I'm anticipating problems with fill-out when using this mold and was wondering if anyone else has noticed this or is having problems with fill-out while using newly manufactured RCBS molds. If I do have a problem during casting, would I be better off writing RCBS to ask for a repair/replacement or try to fix it myself? The vent lines in the shank and base area are so shallow, they're no more than scratches but in the nose area they seem deep enough to bleed off some air. If RCBS isn't guaranteeing their work anymore I suppose I could just shim the mold at the top with some Aluminum tape or maybe put a slight bevel at the top where the blocks come together. I think I ordered the mold at the end of March from Graf.

MJ

[Blammer]

try it first, there are some mould of mine that are similar and yet fill out very nicely

[NVcurmudgeon]

I was getting some molds ready for an upcoming casting session and noticed how the vent lines on my brand new RCBS 35-180-SILH are mere scratches compared to those on my RCBS 35-200-FN. When the 35-200-FN is turned sideways and put in front of a light source, light can be seen through the mold in the shank area which is not the case with the new 35-180-SILH. I'm anticipating problems with fill-out when using this mold and was wondering if anyone else has noticed this or is having problems with fill-out while using newly manufactured RCBS molds. If I do have a problem during casting, would I be better off writing RCBS to ask for a repair/replacement or try to fix it myself? The vent lines in the shank and base area are so shallow, they're no more than scratches but in the nose area they seem deep enough to bleed off some air. If RCBS isn't guaranteeing their work anymore I suppose I could just shim the mold at the top with some Aluminum tape or maybe put a slight bevel at the top where the blocks come together. I think I ordered the mold at the end of March from Graf.

MJ

I'd give it a test run first before hacking and hewing at the mould. "Use the RCBS Force, Luke." Nobody has a more generous warranty than RCBS. If you are using WW, try adding 2% tin for flowability, not adjusting the sprue cutter too tight, and maybe a little higher alloy temperature. I have an old Ideal 311413 with no vent lines at all, and it is among my easiest casting moulds.

[muskeg13]

I've also noticed that most of the new molds I have bought in the last few years seemed to have the air vent lines cut too shallow. I've seen this on RCBS, Lyman and of course Lee molds. Just as a routine mold prep step, I now run a sharp scribe along all vent lines in a new mold and then deburr all mating surfaces. After this, I don't have problems with fill out as I did before.

My latest mold was a 12 ga, 525 gr Lyman hollow based sabot. After my pre-cast treatment, I began casting good slugs after the first 3.

[martinibelgian]

I'll agree to testing it before crying foul - I have several moulds from custom makers, made to measure, and they cast just fine without vent lines - no fillout problems, nothing. Seems to me that vent lines aren't really needed for good casting. Sure, you might need to run it a little hotter, maybe add some tin, but usually they will cast.
I alsos have an Cap'n Morgan mould which might just have the most intricatre venting system ever, and it doesn't cast any better. I might be a bit more tolerant of temp differences, but not that much.
Bottom line - if it works, don't mess with it...

[cuzinbruce]

Hi,
Try it. I have a couple RCBS molds with the deeper lines and I think they are too deep. Very prone to whiskers on the side of the bullet. Have to turn the temp down. Especially with a bottom pour furnace.
Bruce

[leftiye]

Fwiw, a gap of - say .001" between the blocks would vent probly better than is needed, so long as the gap wasn't big enough to produce fins. A piece of "beagle" tape in all 4 corners? Not really advocating this be done unless the mold is undersized or otherwise needed beagling. Just ilustrating another way to get muy excellent venting.

[runfiverun]

don't force feed it, it'll be happy.

[scrapcan]

all of the old winchester moulds on my shelf have no vent lines, and a marlin/ideal mould for 32 win special has no vent lines. All of them will cast well once you get the feel for each individual moulds.

[johnly]

I just finished my first session with a 35-180-SIL mold I just picked up. It cast beautiful looking bullets, but the shank seems a bit big for Hornady gas checks.

John

[Southron Sanders]

A friend of mine that was casting the BIG .58 Minie Balls in his Lyman mould felt he needed to increase the "venting" of his mould. He got one of those little triangular files and used the edge to file in some additional vent lines!

Just don't cut your vent lines TOO DEEP. Nuf Said.