Two rifles of a U.S. manufacturer of firearms are incorporated into the flag and the national emblem of which Central American country?

Two Remington rifles are shown on the coat of arms of Guatemala. It's the type of rifle that was used during the 1871 Liberal Revolution of the coutry. The coat of arms is also shown on the Gutemaltecan flag.

https://en.wikipedia.org/wiki/Coat_of_arms_of_Guatemala
https://en.wikipedia.org/wiki/Flag_of_Guatemala

Both the flag and the coat of arms were regulated in detail by a decree signed by then president Julio César Méndez Montenegro on 12 September 1968. Article 6 of that decree reads:

Los rifles Remington de la época de su creación (1871) se representan con bayonetas triangulares, caladas de perfil con el guardamonte hacia abajo y entrecruzados en ángulo recto en el centro del escudo.

The Remington rifles of 1871 shall be shown with triangular bayonets in side view with the trigger guard down and crossed at right angle in the centre of the shield.

https://hoyhistoriagt.org/2018/09/12/12-de-septiembre-de-1968-por-acuerdo-gubernativo-el-gobierno-del-licenciado-julio-cesar-mendez-montenegro-reglamenta-en-detalle-las-especificaciones-de-la-bandera-y-del-escudo-de-guatemala/