Hello:
Tx, DRYDOCK. SORRY for miss-stating. I confirmed that almost all AS's have too FAST a twist rate, which requires a longer than practical bullet that won't fit or feed through the magazine. The experts here have indicated original 1860's and 1865's usually had 48" twists. Larry took his to 36" and later 32", with his flat-nosed bullet for centerfire rounds in a tube magazine.
Measuring twist is not as simple as drawing or pushing a tight patch and measuring rod rotation because there is usually a LAG at the beginning of the stroke. I have seen twists miss-measured by as much as two inches and then typo'd by ten inches. In one case 48" became first 58" and later 60" for the same barrel in a posting.
So, please be careful: There are a lot of well meant forum postings about repro Spencers by AS and Romano that contain either insufficient or incorrect information via typo's and missing important details. I just goofed with slow vs fast and Drydock caught it!
Larry Romano has used 36" and most recently 32" twists with a 320 grain, single large grease groove bullet of his design. That bullet (mold) is available from custom makers such as Old West and Accurate Bullet molds. I can send you a drawing that was used by one of these to duplicate the Romano mold, which he no longer makes. The key is the large lube groove. Most commonly adapted, modified 50-70 Sharps bullets have inadequate grooves when shortened a groove or two to reach the correct weight/ length. 35 grains of 3Fg Goex and any fairly stiff (relative to minie ball, CRISCO formulations) BLACK POWDER lube such as SPG, MCM or LEN's Lube will be fine. The bullet alloy should be hard at approximately 16BHN because of the relatively shallow grooves. Size to .002" over GROOVE diameter. Barely expand the case mouth so that the bullet fits tightly in case and use MINIMUM crimp, just enough to remove outer case mouth edge. AVOID Lyman dies and get CH4D ones. If using STAR brass, be sure to recognize that there is more internal taper and a STRAIGHT expander die will over expand lower in the case and often create bullet looseness.
He prefers 32" and it is as accurate as your eyes with his bullet and load.
Larry has done at least a hundred Spencer barrels. His CHAMBER reamer is a Pacific Tool, bore piloted one that cuts a very uniform chamber with no slop. Import Spencer chambers can be all over the place.
The AS ITALIAN GOV'T approved chamber specifications drawing was posted somewhere on this Forum a while ago. While in metric dimensions, when converted to English, it contains overly TIGHT dimensions that are NOT in AS chambers! I can send you a copy.
Call or email Larry, via Romano Rifle Company.
Regards,
El Supremo/Kevin Tinny
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