Ruger SBH throat/bore size

[E.J.W.]

I've inherited a like new Ruger SBH 44 mag circa '74 pre warning.
I am getting a lot of barrel leading even with the popular 7 gr of Unique under a 240 gr LSWC.
The commercial bullets I have are sized at .430", I slugged the cylinders of the SBH and got .432". I have not slugged the barrel yet for fear of getting the slug stuck and not being able to reverse it back out the muzzle since the barrel is fixed to the frame. Unfounded fear? maybe?
I'm going on the assumption that .430" is slightly too small and gas cutting is causing the leading. .431" & .432" are available from the company if I need to change size. I've been buying their bullets for years without a single issue of leading until now.
I'm hoping someone here can "cast" some experience on my issue.
Thanks in advance for all and any replies.
E.

 

[rays44]

You won't get the slug stuck in the barrel. You can coat the bore with WD40 (although you don't need to) as this will help the lead slug push through. Use a wood dowel for best results.
Your bullets are .002" under cylinder throat size. Ideally, you want lead bullets at throat size and about .001" over bore size. This is rarely the case, especially in .45 long Colt revolvers where cylinder throats can run .457 with a .451 bore.
My Ruger .44's generally run .430 in the bore. Slug the barrel and get your bore size. If it's like mine, a .431 bullet would be the best size fit.
The BHN of your bullets is also critical. The low power load you're using will require a cast lead bullet at 12 to 15 BHN. Common hard cast bullets at around 20 BHN are too hard and won't obturate at that pressure. So, contrary to popular belief, a bullet that is too hard for CUP of the load your shooting will actually cause more leading.
Lastly, gas check bullets help to reduce leading although they cost quite a bit more. They're also best suited for much higher velocities and higher pressure loads. Hope this helps.