[2][3] Upon its introduction in 1908, the .333 Jeffery firing the 300 grain bullet quickly developed an excellent reputation due to the very high sectional density and exceptional penetration of the round.

Unfortunately the original 250 grain bullet was a copper-capped hollowpoint that was too fragile to be fired at 2,500 feet per second, making it unpopular and marring the .333 Jeffery's reputation for some time.

As with many British proprietary cartridges, the .333 Jeffery was forced into obsolescence when Kynoch suspended ammunition manufacturing in the 1960s, Kynamco resumed manufacture of the Kynoch range of cartridges in the 1990s meaning the ammunition is again commercially available, although no firearms manufacturers make factory rifles in .333 Jeffery today.

In his African Rifles and Cartridges, John "Pondoro" Taylor wrote of the .333 Jeffery, "Time and again have I driven it the length of an animal’s body, and cut the perfectly mushroomed bullet out of his hindquarters.

[8] In his Sniping in France 1914-18, MAJ H. Hesketh-Prichard, DSO, MC, stated "I proceeded to try on these plates all kinds of rifles, from Jeffery’s high velocity .333 to heavy elephant guns of various bores, and was delighted to find the bullets from the .333, as well as the elephant guns, pierced them like butter.