@Gordon Shumway - 

Are you just wanting to mute while practicing, or also while playing in your orchestra?  

Are ALL of your violins equally bright/and or loud?  

I don't have that problem, don't think my instruments come anywhere near the amount of projection I've heard in some wood violins (but what we hear under our ear can differ).  I can play loud, but I can also play a full bow stroke softly (playing ANY kind of full-length bow stroke is a feat for me, because I'm sitting on my bed).  

Anyway, after the recent discussion on The Session (OP of 'Playing in Flat Keys Thread'), talking about 'A' string properties (The "A" string thread), and (to some extent) older threads about 'wolf tones' - made me think about the use of 'tuning', to tame an overly bright violin.  

Granted, there's a huge range of qualities available in strings today (except for my Violin C & F strings 😒).  BUT... Soloists, Bands & Orchestras have traditionally 'tuned UP' to have more impact on an audience, cut through chatter - sound 'brighter'.  

In the same sense, early fiddlers only had access to steel wire for strings.  The brightness/harshness can be overwhelming when adding the power of doublestops - hence you'll find folks 'tuning DOWN'.   

From what I've learned that can cause 'wolf tones', it doesn't surprise me that violins might resonate/sound better with even the slightly difference in tuning overall - OR from one string to the next.  

I understand having several fiddles - each tuned differently, for folks who change tuning often.  I think to change tuning every day might be too much, but what about once a week?  

As an option - getting used to tuning down a half step during the week for practice is easy to get used to... and might let you enjoy playing your violin to the fullest at home without a mute (you shouldn't be used to playing open strings with Classical music anyway).  Tuning back up before your Orchestra meets, you should be fine running through a quick couple scales to familiar finger & hand placement.