Well, after redo'ing the trigger so it breaks at 6-7 lbs, and redo'ing the firing pin block, I now have my spencer 100% reliable and VERY easy to shoot.
45gr of GOEX Express FFg requires an aweful amount of compression.
41gr of GOEX Express FFg seats much nicer and doesn't change the groups that much.
In both cases, I was shooting about 5" at 100 yards, which is about all my eyes and those crappy sights are good for.
Much better results at 50 yards.
At 25 yards, all 5 shots were touching. Again, tough to say w/o thinning the front blade.
I am going to try GOEX FFFg again with the new setup next spring... for now, Large Rifle Magnum primers and a drilled out flash hole has made all the difference.
I might try thinning the blade a bit and reblue... depends on how I feel about it come spring.
[I am all sighted in for MN Deer season... don't care to mess around with stuff that ain't broke at this point]