Does anyone have any experience using Viper internals in a non Viper GBBR? I'm interested to see if anyone used Element steel internals as well since I heard they were decent for the price lol.

Viper internals are the same as pre-2008 INO internals. I recycled my broken INO's working internals in a G&P body and they worked fine. What is the brand of the receiver that you are trying to put the internals into?

Only slight problem I had was the firing block being a bitch to fit in but I swapped it with a G&P block instead. I'm sure if you really wanted to get the INO/Viper firing block to fit, a few careful taps with a rubber mallet would probably work (you'd have to be really careful, since a little too low and you could have gas efficiency/cycling issues and a little too high could cause the BCG to do weird things).

I ahd a Element bearing hammer, looked nice and all, but when in AUTO, the auto sear would slip , resulting in Semi-auto.....