I have a milled P07C (Gen 1 P09C) and it has to be one of the most underrated EDC guns there is. I upgraded the hammer spring, fire control system, installed the Cajun Gun Works P series spring upgrade and heavy duty firing pin. The SA pull is ridiculous and the DA pull is sublime. The gun...
So many “I woulda been fast ropin’ out of those Blackhawks with the boys, but my shin splints…” stories. I think him and Trump went to the same Doc In Canada.
The problem you have is the gun is designated a pistol because of the brace which prevents you having to declare it a Short Barreled Rifle. If you put a stock on it you have to SBR it regardless of the length of the barrel that goes on afterward. The brace/stock change is the issue, not the barrel.
Once it’s SBRd it’s SBRd. You can go back and forth between barrel sizes as your heart pleases. It doesn’t un-become an SBR. BTW, as per ATF regs you have to get the lower engraved to reflect you as the builder.
There is a process to get the SBR designation removed if - for instance - you...
The lower is the serialized part and because it has the fire control system is legally considered the firearm. What kind upper and barrel length goes on it makes no difference once the lower is SBRd.