USC to UMP conversion - swapping internals

[TooSixy]

I am thinking about doing the USC to UMP conversion and have a newbie question, if you don't mind.

If I get the FBI style UMP lower (like this one here on HKParts), I do not have to swap out its internals with the USC internals because it is already S/F (0,1)? Now if I get the Navy style UMP lower, I have to swap out the internals with my USC internals?

Or do I have to swap out the internals regardless of whether FBI or Navy?

Thanks guys!

[S5TIIOwner]

Allegedly legally you have to swap even on the fbi lower.
I will not tell you to knock out the roll pin closest to the mag well, remove the trip, reinsert roll pin and install.

I did the swap so I keep the fbi parts in my bin in the event of an emergency.

Advantage of the fbi lower is no need to mod your selector lever indicator.

[S5TIIOwner]

How to convert a G36 lower with SL8 FCG

[AviatorDave]

Yes, that's one nice thing about the FBI lower - the markings are the same as the UMP lower so they all line up.

[chopperduke]

I would like to thank TooSixy for starting this thread.

I was having the same questions. Is the best route to go an FBI lower?

[S5TIIOwner]

It's all preference. Since you have to swap all of the internals anyway, its only a couple of minutes difference to mod the left side selector.

Build and enjoy.

[TooSixy]

Thanks, guys. I just remembered one of the reasons that I need to swap the internals is because I need to swap the USC trigger with a compliant US-made trigger. Maybe a US-made sear as well for 922r.

[AviatorDave]

The only one I'd suggest staying away from is the burst pack. The selector is configured differently than the USC, FBI, and SEF packs, so moving the parts from one to another requires modifying the internal parts.

[TooSixy]

The only one I'd suggest staying away from is the burst pack. The selector is configured differently than the USC, FBI, and SEF packs, so moving the parts from one to another requires modifying the internal parts.

Dave, is this what you referred to as the Burst pack?

[U.S. Praetorian]

Allegedly legally.....
.

Yes, allegation only. There is no documentable evidence confirming this.