Ive got one of these too, LOVE IT. Anyway it would be difficult to turn your current housing back to a USGI/convert a screwed magazine guide trigger group to the 1918A3 design. One mod that the OOW boys do to the trigger group is add a second set of holes to the trigger group to secure it. On the fulll rock and roll models only one hole/pin is used to hold the trigger group in the receiver.Maybe I wasn't as clear as I needed to be. I have an OOW 1918a3. It has an armasteel trigger housing. Can I take the parts out of the OOW trigger assembly and use in the original GI assembly? I would like to use a GI trigger housing that has the screw on magazine guides to give it the look of a modernized BAR. Your comments are certainly welcome.
Beat me to it. Was some machining due to a change in receiver to prevent a full auto trigger group from bring inserted without modification. Older 1918a3s had usgi trigger groups machined to find and to fit the semi auto parts. Newer ones like mine had a new group made to all the specs.the only hole drilled is for the semi trigger pivot pin; the 'rear' pin that USMC1488 speaks of is the existing sear trip pin hole.
The mods to the USGI trigger housing are simply milling off the upper lip on the rear (provides a 'block' so a FA trigger group won't fit into a semi receiver) and the inside is milled out to receive the semi parts (as mentioned, very similar to a M1 carbine trigger group).
If you have a mill you could machine the USGI to take your OOW guts easily