Well, two can do that! Martin, or MartyH, or whoever else posts under Martin Hammond, or MartyH's account, or however many you have, check out this thread.
http://benchrest.com/showthread.php?72542-New-Tunas-and-a-different-one
I believe you will find a pic of a tuner that violates your 4.6 ounce dictate. It is easy to find, it is the first pic in the first post. After having viewed the pic, I believe you will have to agree it probably weighs more than 4.6 ounces. Yet the shooter apparently shot a 2300 and a couple of 2350's with it. And according to Pete Wass, the guy thought it was a couple of ounces too light!
So, if a 4.6 ounce tuner is the bees knees, how can THAT one work?
Meanwhile, Dan, with the brilliant (and I say that with ALL sincerety) post sits back and chuckles at human nature.
Greg
I am pretty sure that Tuna is NOT going to willingly delete that thread!
I will be nice now.