How much more quiet is a dedicated 5.56 can.... I have all 5.56 rifles right now but may expand that later....

Good question let me expand on this and cover the topic a little more in-depth.

In general 5.56 silencers are quieter than 7.62 silencers however the larger bore size of the 7.62 creates less blowback on the 5.56 rifle. Another thing to consider is that 7.62 silencers are longer, heavier, and generally cost more than their 5.56 counterparts.

Now for the Saker specifically, the 7.62 version is louder than the 5.56 unless you change the end cap out. The Saker is unique in that it has a removable front end cap that you can purchase separately that is a 5.56 bore size. We talk about it in our video of the Saker and post some numbers. Check it out and if you have any questions let me know.

Is the 762 rated down to a 10" 556?

It's rated down to 7" for 5.56.