What is the biggest rifle?

Answer 1

The rifles that shoot the .50 BMG (Browning Machine Gun) round are generally accepted as the largest rifles commercially available. Barrett makes several models as well as other manufacturers. A rifle with a bore larger than 1/2" would be classified as a "destructive device" per the Federal 1968 Gun Control Act and involve additional paperwork and expense to own.

The Germans did field a bolt action rifle with a bore larger than 1/2" during WW1 which was used as an anti-tank rifle. It was impossibly heavy for men to carry and was not considered successful although it would punch a hole through the tanks of the time.

Clearly the .700 Nitro Express is the largest. The Caliber was designed to take down elephants with a single shot. In the USA the .700 Nitro Express requires an additional permit to own.

The .700 Nitro Express developes 2,700 ft/s and 14,374 ft-lbf with a max 1000 gr bullet

The Bullet diameter of the .700 Nitro Express is .700 (17.8 mm)

The .600 Nitro Express developes 2,050 ft/s and 8,400 ft-lbf with a max 900 gr bullet

The bullet diameter of the .600 Nitro Express is (15.24mm)

The .600 Nitro Express is federally exempt from the destructive device category and does not require additional permits to own in the USA

The .50 Cal BMG developes 2,895 ft/s and 14,895 ft-lbf with a max 800gr bullet.

The bullet diameter of the .50 cal bmg is only .510 in (12.95 mm) much smaller than that of the .600 & .700 Nitro.

There are also several other rifles that are larger than the .50 cal and are legal to own in the USA without permits...The .50 cal BMG has the longest cartrige of all the rifles at a max of 5.45 in (138 mm)long. However it is not the largest caliber rifle available to the general public.