I got a head's up on this gun and bought it about a month ago, it finally arrived today. See if you can spot the unusual feature in the first couple pics before scrolling down to read about the details.
Ever since I learned that these existed maybe 15-20 years ago, I had been looking for one. Did you spot the difference setting it apart from a regular 4" blue Police Service Six .357 Mag?
It is the heavy barrel. Note that the rollmark is pre-warning, and the "H" heavy barrel guns did not come around in production quantities until after the warning statement began to appear in 1978. This gun has a 152 serial number prefix and dates to 1977 production. The barrel is not only heavier but the muzzle area around the crown is oddly milled with a protrusion beyond where it would normally terminate. These are noted in the RENE Reference as catalog number SDA-34MB revolvers, the MB standing for "machined barrel". First reported by Sonny Johnson in the March, 1984 RCA Journal, these revolvers are quite rare with only a few examples known (and I have heard that Sonny's collection fell victim to a structure fire years ago). This is the first one I had even seen.
According to Sonny's RCA article, the sight rib is 17/32" wide with 12 grooves as opposed to a standard Service Six barrel rib being 3/8" (or 12/32") wide with only 7 grooves. And he notes the lug is 1/2" wide versus 3/8" on the standard guns. And the barrel is non-tapered 11/16" diameter versus the standard tapered barrel. His theory on the muzzle protrusion is that it was due to a "machine adjustment error" that resulted in the barrels being cut about 1/16" too long. The "machined barrel" designation was because these barrels were machined from bar stock rather than forged. Sonny's article references the model SDA-34MB, so I assume he got his lettered, which I have not yet done with this one. He also indicated that a factory source told him these should have been rejected due to that barrel protrusion. This suggests that there may be other MB guns out in the wilds without the muzzle protrusion (they would of course be more difficult to spot).
According to RENE, there is also a single stainless gun known, model GF-34MB, I'd sure like to find one of those!
Here are some more pics showing the details:
Ever since I learned that these existed maybe 15-20 years ago, I had been looking for one. Did you spot the difference setting it apart from a regular 4" blue Police Service Six .357 Mag?
It is the heavy barrel. Note that the rollmark is pre-warning, and the "H" heavy barrel guns did not come around in production quantities until after the warning statement began to appear in 1978. This gun has a 152 serial number prefix and dates to 1977 production. The barrel is not only heavier but the muzzle area around the crown is oddly milled with a protrusion beyond where it would normally terminate. These are noted in the RENE Reference as catalog number SDA-34MB revolvers, the MB standing for "machined barrel". First reported by Sonny Johnson in the March, 1984 RCA Journal, these revolvers are quite rare with only a few examples known (and I have heard that Sonny's collection fell victim to a structure fire years ago). This is the first one I had even seen.
According to Sonny's RCA article, the sight rib is 17/32" wide with 12 grooves as opposed to a standard Service Six barrel rib being 3/8" (or 12/32") wide with only 7 grooves. And he notes the lug is 1/2" wide versus 3/8" on the standard guns. And the barrel is non-tapered 11/16" diameter versus the standard tapered barrel. His theory on the muzzle protrusion is that it was due to a "machine adjustment error" that resulted in the barrels being cut about 1/16" too long. The "machined barrel" designation was because these barrels were machined from bar stock rather than forged. Sonny's article references the model SDA-34MB, so I assume he got his lettered, which I have not yet done with this one. He also indicated that a factory source told him these should have been rejected due to that barrel protrusion. This suggests that there may be other MB guns out in the wilds without the muzzle protrusion (they would of course be more difficult to spot).
According to RENE, there is also a single stainless gun known, model GF-34MB, I'd sure like to find one of those!
Here are some more pics showing the details: