Hello everyone,
I also posted this on the Cast Boolits forum and our Ask The Gunwriters forum. I have some concerns about my beautiful new 4 5/8" .32 H&R Single Six. It's an older "New Model" that I have not yet fired, just recently bought it from a member over at 24hourcampfire. He said it only had about 50 rounds through it and it looks it - it's pristine.
Thought I would try out a few different commercial cast bullets before I bought a mould for it. My first batch are the Acme bullet 100 grain FP, which looks to be about the same as the RCBS 32-98 SWC. The bullets I got from Acme are listed as 16 BHN and are powder coated. They are advertised as sized to .313", but based on a small sample most are .3133" with less than half coming in at .3130".
I loaded up 30 at the very mild listed max for the 100 grain in the Lyman book, 2.7 gr. Unique, planning to take it out for its first range trip this week.
I thought I'd better check those bullet versus the cylinder throats (yes, I did this AFTER loading up a bunch...I know...) and was surprised how extremely tight they were. It took a great deal of force to drive one through the throat, and it came out at .311. Uh-oh, time to slug the bore.
I slugged the 6-groove bore and two of the opposing grooves are right at .312 with the other one just over .3125 (how common is this - one groove slightly deeper?).
After taking all my measurements on the soft lead slug multiple times I bumped it up and then used it (instead of the 16 bhn bullet) to slug the throats and again got .311"

Everything I have read says these cylinder throats ought, ideally, to be about .313.
Questions:
1) Are there any safety concerns with a 16 bhn bullet that is at least .002-.0023 over throat diameter being fired with this load (listed at about 13K CUP in the Lyman book)
2) Is it a waste to even shoot these for accuracy? I'd like to at least get my sights set up on paper. Am I going to see a ton of leading?
3) What should I do about the throats? I fixed undersized throats on a Ruger .45 colt cylinder myself using some tricks I think I read in Ross Seyfried article probably 30 years ago but what I did then would be harder, I think on this much smaller cylinder.

Thanks in advance,
Rex