Single trigger

[William Stevenson]

I know we've beat this horse before, but I need to ask if anyone has had a similar experience. A couple of years ago I was getting second shot refusal and a rare double (both barrels at the same time) with my single trigger Steel shot special. I sent it to the Miller Single Trigger Co. With the instructions to fix it or install their single trigger. To my surprise, they fixed the gun. ($500) I thought they would surely try to sell me their trigger, ($1,200) but they didn't. I used it several times with no problem, till this morning.
It seems that when I get in a hurry with surprise ducks coming in, I don't get it firmly on my shoulder. Would that situation cause second shot refusal or doubling due to too much "give" for the inertia mechanism to work properly? I'm shooting with the gun on my upper arm on occasion and it seems to malfunction at those times. Am I dreaming this up or can it work (or not work) as I've described? It doubled and didn't fire the second shot on another occasion this morning. Could it be me or is it definitely the gun? Don't want to buy a Miller trigger but I will if I have to. Thanks. Bill