Rossi 461 Trigger Quirks

[jimbeam338]

I shot a friends Rossi 461 revolver and the single action trigger weight is different for each shot. I noticed it while firing it, and then i loaded so the same chamber would shoot first every time, and then count off each shot. Shot one would be light, shot two would be heavier, shot 3, 4, and 5 would be extremely light, then shot six about the same as shot 1. What determines the single action trigger weight in these revolvers? By the way the double action trigger feels about the same for all shots. The guy who owns it says its a bummer because it throws him off to have each shot different than the one before as its hard to get used to the trigger by way of practice in this case.