The federal prohibition on firearm possession is on anyone "who has been convicted" of a felony, 18 USC 922(g). While 17(b) makes a prior wobbler felony a misdemeanor "for all purposes," People v. Gilbreth (2007) 156 Cal. App. 4th 53, 57-58, the federal law facially seems to look at the time of conviction, and is not bound by what state law says it was, or, more properly, now says it was. The federal court defines felony by the maximum sentence, United States v. Pruner, 606 F.2d 871, 873 (9th Cir. 1979), without regard to the actual sentence. The Ninth Circuit seems to consider a misdemeanor a wobbler that was originally sentenced as a misdemeanor under PC 17(b)(1), but explicitly did not reach the question of whether a wobbler initially a felony conviction but later reduced to a misdemeanor under PC 17(b)(3) is now a felony under federal law. United States v. Bridgeforth, 441 F.3d 864, 872 (9th Cir. 2006). Therefore, in the Ninth Circuit, I would not right now feel safe carrying a weapon after receiving a PC 17(b)(3) reduction, although I would if I was initially sentenced to a misdemeanor under PC 17(b)(1). I believe the Ninth has rejected the contention that PC 17(b)(3) restores releases you from 18 USC 922(g) liability in Pruner and in United State v. Houston, 547 F.2d 104 (1976). Another circuit has no clue how to deal with PC 17(b). So if your lawyer is telling you that he can restore your gun rights with a PC 17(b) reduction, you are at the mercy of 13 federal circuits, most of whom have never heard of PC 17(b) and will find it a strange creature once your client gets caught with a gun there.