Mould blocks- Pin/Socket readjustment?

[NC REDDOG]

Milhec H&G 68 clone. Fourth casting session with this mould and suddenly having problems. First three times mould dropped beautiful boolits and functioned flawlessly. Now the two forward (assume handles to the rear) cavities producing finned projectiles. I can observe the gap between the blocks. Looked for the obvious causes. Inspected for any deposits on block faces, in and around pins and sockets. Relubed. Still not mating correctly. Removed blocks from the handles to assess the situation and here is what I have discovered. The forward socket will not allow the pin to seat deep enough for complete block face to face contact. I determined this by rotating the blocks and test fitting both pins and sockets with each other. Rear socket accepts both pins and allows perfect mating of the blocks. Both pins inserted in the front socket produce " uneven/ loose " surface to surface contact. Naturally I re-examined the socket with a magnifying lens to confirm no hidden lead deposits. Unclear as to what change has taken place, but at this point I am prepared to simply open up the front socket diameter a smidge to solve the issue. Any thoughts or suggestions?

[Springfield]

Heat it up and compress it in a vice until one or both of the sockets move back into the mould and match again. Or heat it up and use a lead hammer, both work. Sometimes the pins just move forward.

[NC REDDOG]

If the pin moved wouldn’t I have the same uneven mating when inserting it in the other socket? This is why I am assuming the socket insert has shifted.

[NC REDDOG]

Reread Springfield reply. Makes perfect sense. Apply force/ pressure to mould blocks in order to reseat pins and/or socket inserts. Thank you for the advice.

[Walter Laich]

Heat it up and compress it in a vice until one or both of the sockets move back into the mould and match again. Or heat it up and use a lead hammer, both work. Sometimes the pins just move forward.

I had a new mold that didn't completely close once it got hot. I would give it a tap with a lead hammer while the mold was sitting on its side on a lead ingot. did this for about a dozen or so times. Skipped on hammering cycle and lo and behold--no longer a problem

still is one of my best casting molds

[NC REDDOG]

Just came out to the shop and heated the mould. Wooden mallet, couple of wood scrap blocks and two firm strikes. Looking good. Firing up the pot now. I will report back but imagine happy days are here again for this mould.

[Bazoo]

Reddog, hope you get it sorted out. Welcome to the forum!

[NC REDDOG]

Not the results I was hoping for. After seating the pins and obtaining full contact between blocks with the method described previously I began casting with optimism. Didn't last long. Although the mould was not quite up to temp and the boolits were shiny, first few pours produced projectiles free of any fins. Quality quickly deteriorated. Spent the next few hours manipulating different variables in an attempt to eliminate or at least mitigate the problem. Following I list some and note the results. In the end, in the best of circumstances, I was casting boolits where the two most forward have slight nose fins with second cavity from the front being almost negligible.
Swapped out the handles, Lee for RCBS. Slight improvement.
Lay the mould on its side on the edge of bench and strike a firm blow with the meaty area of palm. This was necessary after each cast in order to have any success.
Reduce sprue puddle. More effective and noticeable with higher alloy temps.
Pour at the lowest acceptable temp. Sweet spot at around 680f. Temps at or above 725f resulted in nose fins all four cavities and substantial side fins front two.

I should note that opening the mould requires both hands as front pin is quite sticky unless after one of the first 3-4 casts following lubing. This is the reason I am wondering if opening up the front socket insert is not a possibility. Although I am quite careful to not overheat my moulds ( this is a 4 cav. brass ) another possibility is that one or both blocks have warped. Doubtful as a machinist straight edge shows no indication and when press together manually the block faces mate perfectly. Seeking advice from this knowledgeable community.

Not to be remiss, thank you for the welcome Bazoo.

[Echo]

NC, I had a similar problem with An NOE 4-banger. Called and asked Swede what to do. He said use a tapered reamer (as we all have!) and touch the offending socket a bit. Did, but didn't work. I have a longer-taper reamer from decades ago when I was doing electronic construction, and tried it. Bingo! Took out just enough to allow the pin to enter and register. Problem solved...

[NC REDDOG]

Thank you for the input Echo. This is right in line with my thinking. As much as I hate to take a tool to the handiwork of a craftsman such as Miha, I believe the attempt is warranted. The photo of the reamer you posted looks vaguely familiar. I believe my Dad has a similar one floating around in his shop. I will give it a try with high hopes of success.

[AggieEE]

Before you do anything irreversible try this. Loosen the holding pins(?), the ones with the e-clip on them, slightly. I have a couple of Miha's molds and if I tighten the pins there is binding moving the nose pins in and out. A little loose and the mold works like a champ.

[Echo]

Before you do anything irreversible try this. Loosen the holding pins(?), the ones with the e-clip on them, slightly. I have a couple of Miha's molds and if I tighten the pins there is binding moving the nose pins in and out. A little loose and the mold works like a champ.

And consider a touch of WD or whatever to the outside of the pins. I lube (sparingly!) w/Bullplate the mounting pins, and find that in order to remove & exchange, that loob must be removed, or else the tight tolerance of the pins causes the pins to need force to remove, possibly due to oxidation of the loob - might be binding on closure, too.