In this case, 45 is caliber, 6 means commander size, and the 7 means decocking. It's the .45 version of the 1076, manufactured for a short time during Smith's "gun of the week" period.
There is actually some variance in the system Smith has used. The first two numbers will designate caliber and capacity: 39 means single stack 9; 59 means double stack 9mm; 45 means single stack .45 (all .45s have this designation since Smith doesn't make a high cap .45; the exception here is the 945 which is a progressive development of the 745/845 competition weapons). 40 causes a problem as it can be a single or double stack, depending on when it was produced.
The second set of letters can mean frame type (stainless/alloy, blue/alloy or stainless being designated as 03, 04 and 06 respectively), or safety design (43 being doubleaction only and 67 standing for decocking).
There is actually some variance in the system Smith has used. The first two numbers will designate caliber and capacity: 39 means single stack 9; 59 means double stack 9mm; 45 means single stack .45 (all .45s have this designation since Smith doesn't make a high cap .45; the exception here is the 945 which is a progressive development of the 745/845 competition weapons). 40 causes a problem as it can be a single or double stack, depending on when it was produced.
The second set of letters can mean frame type (stainless/alloy, blue/alloy or stainless being designated as 03, 04 and 06 respectively), or safety design (43 being doubleaction only and 67 standing for decocking).
