Heat can definitely be your ally in this game. So can a bit of added tin.
I have an OLD single-cav Ideal mould #225438. The guy who sold it to me @ $20 said "I have never gotten a decent casting out of it. THANK YOU for getting it outta my sight."
Here--HOLD MY DIET COKE.
Nice-condition tool, no visible vent lines (yeah, OLD) and no signs of past abuse. Pre-heat the block, and try it with Linotype. OMG--beautiful castings. Very few throw-backs. Aight. Next try was with 92/6/2--got the alloy temp up around 775*, and it made good castings--with about 10% scrap rate. I can live with that, and the castings shot well in a 22 Hornet at 100 and 200 yards.
But that Linotype result kept rattling around in my head. There's lots of unused room. Loverin bullets and their tiny grooves/bands. Good fill-out with Lino, and very close weight SDs. Lyman "specs" for Lyman #2 alloy. #2 is 5% tin.
I bought some tin bars from Roto, and added about 2% more tin to my 92/6/2 for my next Loverin bullet, a new #266469. I heat-cycled the mould over an afternoon, 3 or 4 times. I heated it back up after complete cool-down, and started pouring bullets with my custom/one-off 91/5/4. The fourth pour produced keeper castings, and continued to do so. This will become The Standard whenever a Loverin-like design is in the mix. I feel confident that similar steps will help with the Ranch Dog or other tumble-lube castings are on the menu.