Another awesome report Josh. That description of the 91/30 sounds like a real find! All but 2 of the ones I've owned took me a day of cleaning cosmoline to get a chance to even see the metal.
Good looking Mosin from the Pix. Good price too! I just dropped $120 on an unissued 91/30 hex reciver at the Indy 1500. I'll get a pix up as soon as I can remember my login at Photo Bucket. Havent used it in a long Time!
On bull barrels, you want to free-float them for optimum accuracy and have known pressure points on the receiver. This keeps the weapon's harmonics as close as possible.
When you start doing this with military and sporter-style barrels, however, they will shoot in circles as they heat up due to heat warping.
By shimming the action, you get two known pressure points on it. Same result as glass bedding the action, for all intents and purposes.
On a modern rifle I would glass bed the barrel. However, this being a nice old Mosin, I'm taking a cue from the Finns and putting shims in for known pressure points.
Last night I did away with the .010" shims (too many and too easy to lose) and put a known pressure point at the end of the barrel with cork/rubber gasket, and just forward of the receiver as well. I do not yet know how this will shoot. Was planning to test it out today, but I have a hell of a headache and am waiting for antihistamines to kick in. I would not be on my top game like I was yesterday and it would not be a fair comparison.
I therefore refer you to this sight where they did the same thing (brought to my attention after I had done mine with metal):
I've been really tempted to get one of those and last time I was at Midwest I decided to. Unfortunately all the Mosin's they had were very beat-up with "new" damage I guess from customers rummaging through the crate to find a good one.