There are several members of RFC who are very active silhouette competitors, including at least one national champion, who could definitively answer this question but I'll take a crack at it.
The rules for Smallbore Hunter Rifle class limit the weight of the rifle to 8 1/2 pounds with sights. The 1712 is a 7 1/4 pound rifle where the 1710 Heavy Barrel is an 8 pound rifle. This allows the 1712 to make weight after adding a light silhouette scope and lightweight high rings (up to 1 1/2 inches from the top of the receiver to the bottom of the scope tube), which many experienced silhouette shooters prefer. Anschutz is making the 1712 as heavy as possible, yet still allow it to make weight in Hunter Class with reasonable sights.
Second, the 1712 stock is designed with a high cheek piece, but with a lower butt (more drop at the heel and toe) than the 1710. This stock allows for a more upright head position when coupled with high rings, which allows ones eyes to be more level and neck more relaxed, conducive to good offhand shooting. The raised sight line also serves to lower the center of gravity of the rifle, which is helpful. At the same time, the lower butt of the 1712 stock allows for a more relaxed shoulder position while shooting standing.
In summary, the 1712 is made as heavy as possible while still allowing it to make weight with a scope and with a stock that is more comfortable for offhand shooting. That is my take.