Brass is an alloy containing Zinc as the principal alloying element with or without other designated alloys such as Tin, Aluminum, Nickel, and Lead . By Comparison Bronze is principally an alloy of Copper and Tin. Bronze does not necessarily contain Tin, and a variety of alloys of Copper, including alloys with Iron, Phosphorus, Lead, Aluminum, Manganese, and Silicon are commonly termed Bronze.
In fact all are Brass in metallurgy. the name bronze come from anticity and still be use today.
Tin and Zinc at 5% as alloying elements do not change the weight for the coins at 19 mm diameter and this tightness. The reason for change from the 95% cooper, 5% zinc and tin in 1962 to 95% cooper and 5% zinc, was not just the price of the tin but also of the elasticity proprieties of the alloy.
Just analyze that all the cents from 1909 till now has max. 3.11gr and min. 2.98 gr mint acceptable weight.
Never argue with an idiot. First they will drag you down to their level. Then, they will beat you with experience. (MARK TWAIN)