Guillermo Baldwin had the following podium finishes at major championships: 2nd in the 1951 Pan American Games 50 m rifle prone team (with Enrique Baldwin, Rubén Váldez and the non-Olympians Elias Benavides, and Julio Poggi), 2nd in the 1951 Pan American Games army rifle 3 positions team (with Luis Albornoz, Carlos Lastarria, and the non-Olympians Gregorio Valdivia and Leonidas Bernal), 2nd in the 1959 Pan American Games small-bore rifle prone team (with Carlos Lastarria, Oscar Caceres, and the non-Olympian Lita Baldwin), 3rd in the 1951 Pan American Games 50 m rifle 3 positions team (with Enrique Baldwin, Luis Albornoz, Rubén Váldez, and Luis Mantilla), 3rd in the 1959 Pan American Games 300 m high power rilfe 3 positions team (with Luis Albornoz and the non-Olympians Rodolfo Váldez and Teodoro Bullón).