The 146 are rare but yours is more rare. Here's the only serial #s in your category I've been able to record so far:
0. "Rare misc. non-Brit Contract commercial production/shipped 44 TL 1st Models chambered in .455."
Including a non-Brit Contract special order TL subset of 25 standard .44 1st Model TLs in the .44 serial # range chambered in .45 Eley (per letter) with 5" barrels, shipped Nov. 1, 1912. Thx to Jim Fisher for bringing these to our attention and sharing documentation! See #5751 below.
A Scarce 5 Inch Triple lock shipped to Canada in April of 1915
5642 – NO CTG ROLLMARK shipped April 1915, a rare commercial shipment per Roy
5724 - NO CTG ROLLMARK 455 single gun shipment April 28,1915, from Canada
5751 - Caliber is 45 Eley, shipped in 1912 in a commercial order of 25, 5" guns to H. Robitsek, Canada
5788 - NO CTG ROLLMARK, Canadian 6 1/2" barrel shipped June 4, 1915 in an order of 5 to Hurd & Co.
7827 - NO CTG ROLLMARK, in Germany
1. "44 Hand Ejector-1st Model Triple Lock", 812 (666 military & 146 commercially sold all with known serial #s) in the 44 Spl # series factory converted to 455, with no Smith & Wesson or cartridge markinghe serial #s for the 146 and where and when they shipped are on page 203, S&W 1857 - 1945, and they're all much higher serial #s ranges than yours. Most weren't sold until 1918.
Apparently once S&W began producing the category 2. TLs below, they quit shipping 44 HE 1st models converted to 455.
2. "455 Hand Ejector-1st Model Triple Lock" #1 thru #5461.