Did I screw up my mold??

[Someflyers]

I am not an expert (or even close) but have
cast a few thousand rounds of various calibers that shoot well and am having a blast doing it.

I have an RCBS 115gr RN mold
that up until now has been a good producer of 9mm rounds. I have run about 2000 boolits through this mold. All of a sudden this week the front chamber is casting rounds with large fins on the nose and the lead is flowing out the vent lines on the sides of the nose as well. The rear hole is still working well and making nice boolits.

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When I look at the mold in the light, there is a significant difference in the gap between the two halves in the top hole vs the bottom one. The halves seem to pivot on the handles freely and the pins seem to be engaged in the alignment holes. Did I warp this mold somehow?? I do preheat on a flat hotplate on med-low for just the last few minutes of pot warm-up.

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I pretty sure it's my fault somehow ( hey, been married 25yrs!! It always my fault!) but thought I was being careful with my molds. I just don't want to do it to another of my more useful molds. Is there any remedy for the situation I find myself in or am I just going to have to come up with another mold??

[OuchHot!]

Yeah, a quarter century of marriage certainly reoriented my sense of accountability. BUT I have not yet seen rcbs blocks warp so I'm inclined to think that an alignment pin has shifted or there is a burr somewhere keeping the blocks from closing. I suspect it is something simple but will need careful investigation to find. RCBS may warranty these, I don't know.

[texassako]

Check the mold faces for specks of lead, and the alignment pins and holes for burrs, debris, or movement.

[MarkP]

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Check for splatter first on the faces of the mold halves. RCBS molds have a shoulder on the alignment pins the pin may need a slight tap to reseat.

I had a 244-95 mold that came from the factory that way, the RCBS tech told me to use a deburring tool on the bushing or tap the pin slightly such that it was still kind of sticky when separating the two halves. I did not want to use a deburring tool as I knew there were other issues with the mold and would most likely need to return it to RCBS. The cavities were cut with about 0.017 gap between halves, when the pins were adjusted such that the halves were touching the boolits had an elliptical cross section. Second mold had the same issue, the third replacement mold was fine.

[tazman]

I suspect you had a locating pin move on you. That will hold the mold apart since the pins are near the bottom of the mold blocks.

[Lumpy grits]

Ck the 'faces' of the mold for specks of lead.
Look for burrs along the outside and with the locator pin holes.
Also check that the mould handle 'fingers', that are around the mould, move easily within the mould and the holding screw is snug.
LG

[aap2]

Easy to fix. Remove the handles and sprue plate and hardware. Support each block cavity down with lead ingots and use a punch on the flat side of the locating pin and tap the pin out of the block; repeat with the other block. Chuck each pin in your drill and polish the rounded head with fine emery to remove any burrs. Use a cartridge case deburring tool to deburr the mating holes for each locator pin. Get a clean very fine cut file and gently pass the the face of the block over the file for a few strokes. Repeat for the other block. The high spots will show up bright. Often you will see bright rings around the locating pin holes and around the cavities themselves. Put a piece of fine emery paper on a flat surface, add a few drops of oil and polish each mating face of the blocks. Clean to remove any grit and tap the locating pins back in with a brass punch; if the mould is slightly "sticky" when you open it the pin(s) needs to be tapped in a little more. You might just get away with just tapping a pin in to eliminate the gap, but this entire procedure only takes a short time and you will be sure that your mating surfaces are flat. Good luck.

[Moonie]

I'm betting you have a small bit of lead on the face of one of the blocks.

[country gent]

First check faces for specks of lead, dings, or other raised surfaces. Use a magnifing glass and look hard. Clean mold good before doing this, dish soap and water scrup good with a toothbrush. emove mold from handles and check each pin to its hole by rotating blocks as needed. Pay attention to pins and holes for burrs or bright spots. Whle out check screws for bends or bows. Clean handles and check for burrs and or bright spots. A handle thats tight on the blocks mount slots can distort the alighnment also. Dirt crud in there can cause problems. Pins can shift and may need some small adjustments made occasionaly. The big thing to remeber is this mould was casting good bullets before so its something that has changed recently. Whie you have the blocks off the handles mate them up uder finger tension and see what the gap is. Im betting there is some lead build up along the bottom back edge holding it open. Work slow and easy with a hardwood stick or brass flat edge to remove spatters or smears.

[bangerjim]

Lead spatter/smear/buildup on the mold faces. Easy to fix!

Or send me the "ruined" mold for proper disposal!

banger

[Someflyers]

No lead on the faces of the mold (looked with a really good set of cheaters!) can't feel any rough spots, edges are all clean. I'll acquire a magnifying glass tomorrow and give it a closer look.

If it is the pins as some have suggested, is the problem that they have drifted out too far?? If so do I have to punch them all the way out and start them in from the back again to put them back in??

Or am I bass ackward??

[Le Loup Solitaire]

The mold is not ruined. It has to be adjusted as advised by those who have already responded. If you have difficulty in doing what has to be done or you do not succeed then simply send the mold blocks back to RCBS and they will either do it for you or replace the blocks. LLS

[.22-10-45]

Take a good look inside alignment holes..I once had a tiny bit of lead get in there.

[Someflyers]

Ahhh. Will do!

[Mk42gunner]

The one and only time I had to adjust alignment pin depth on an iron mold (Lyman) I just drove it back into the mold block. As tough as it was to get it to move a very small fraction of an inch, I really don't want to try to drive one completely out.

Robert

[ShooterAZ]

I had the same problem develop with one of my RCBS molds. I was getting fins and finlets intermittently. My solution was to thoroughly clean the mold, lube the pins & mate the halves, then set on a block of wood. A couple of light whacks with a rubber mallet and the problem went away. Your mileage may vary.

[Someflyers]

Ok got it dropping good boolits again !! And part of it was my fault. The front alignment pin was a bit farther out and a few judicious taps with a hammer and brass punch had it reseated. Also the fingers on the handle had quite a bit of carbon built up on them and I cleaned them up with steel wool

Many thanks for the advice everyone.