Cincinnati Slim
Member
Howdy Y'all,
Got me one of those cheap Franklin Arsenal digital calipers a little while ago and been on a measuring kick ever since. Last night I took some .457 lead balls, a length of wood dowel and a little dead-blow hammer and proceeded to "slug" the bores of a Uberti 1873 SAA "Cattleman", two Pietta 1868 NMA Remmies and a Pietta "sherrif's model" 1860 Army. I have conversion cylinders for both the Colt and Remington cap and ballers. I measured the throats of the cartridge cylinders and the percussion cylinders. The Kirst, R&D and Uberti chamber throats were all pretty much right on at .452 to .4525. The percussion cylinders ran .444 to.447. Then I measured the soft lead balls after pushing them down the bore.
The Uberti barrel has six grooves/lands versus the Pietta seven land/grooves, so that one was easier to measure. The balls with the odd number lands/grooves were placed into the jaws of the caliper and then rotated a smidge to "bump" the caliper open enough to allow the ball to be rotated in the caliper's jaws. This seemed to add about .002 to the initial measurement and was fairly repeatable so I am pretty confident in reasonable accuracy.
In previous shooting with Ultramax and Winchester "cowboy" loads the Pietta C&B revolvers with conversion cylinders were much more accurate than the Uberti SAA. I wondered why so I decided to "slug" the bores and see if that provided a clue. Much to my surprise, the Uberti (.449) didn't have a significantly larger bore than the tighter shooting Piettas (.446-.448).
But when I forced the ball down the bore I discovered that there was a choke or constriction where it was screwed into the frame !
That was the problem...A Taylor throating reamer from Clymer tools was the solution ! You can get 'em from Brownell's. They are hand turned. I worked slowly, used a lot of cutting oil and cut DEEP. Now there is a gentle forcing cone and a full bullet's length of freebore before any rifleing. At last I can actually get this revolver to make decent groups.
Now I need to ream my percussion cylinders' chambers to .448-.450, right now they measure .444-.445, too small to really fill the bore's grooves which measure .446-.448.
Happy Trails,
Cincinnati Slim
Got me one of those cheap Franklin Arsenal digital calipers a little while ago and been on a measuring kick ever since. Last night I took some .457 lead balls, a length of wood dowel and a little dead-blow hammer and proceeded to "slug" the bores of a Uberti 1873 SAA "Cattleman", two Pietta 1868 NMA Remmies and a Pietta "sherrif's model" 1860 Army. I have conversion cylinders for both the Colt and Remington cap and ballers. I measured the throats of the cartridge cylinders and the percussion cylinders. The Kirst, R&D and Uberti chamber throats were all pretty much right on at .452 to .4525. The percussion cylinders ran .444 to.447. Then I measured the soft lead balls after pushing them down the bore.
The Uberti barrel has six grooves/lands versus the Pietta seven land/grooves, so that one was easier to measure. The balls with the odd number lands/grooves were placed into the jaws of the caliper and then rotated a smidge to "bump" the caliper open enough to allow the ball to be rotated in the caliper's jaws. This seemed to add about .002 to the initial measurement and was fairly repeatable so I am pretty confident in reasonable accuracy.
In previous shooting with Ultramax and Winchester "cowboy" loads the Pietta C&B revolvers with conversion cylinders were much more accurate than the Uberti SAA. I wondered why so I decided to "slug" the bores and see if that provided a clue. Much to my surprise, the Uberti (.449) didn't have a significantly larger bore than the tighter shooting Piettas (.446-.448).
But when I forced the ball down the bore I discovered that there was a choke or constriction where it was screwed into the frame !
That was the problem...A Taylor throating reamer from Clymer tools was the solution ! You can get 'em from Brownell's. They are hand turned. I worked slowly, used a lot of cutting oil and cut DEEP. Now there is a gentle forcing cone and a full bullet's length of freebore before any rifleing. At last I can actually get this revolver to make decent groups.
Now I need to ream my percussion cylinders' chambers to .448-.450, right now they measure .444-.445, too small to really fill the bore's grooves which measure .446-.448.
Happy Trails,
Cincinnati Slim
