The 105×617mm (4.1 inch), also known as 105×617mmR, is a common, NATO-standard, tank gun cartridge used in 105 mm guns such as those derived from the Royal Ordnance L7.

The 105×617mmR cartridge was originally developed from the 84 mm (3.3 in) calibre Ordnance QF 20-pounder 84 × 618R cartridge as part of the development of the L7 105 mm rifled gun.

There are different ways to measure penetration value.

NATO uses a criterion that 50% of the shell has to go through the plate, while the Soviet/Russian standard is higher as 80% had to go through.

According to authorities like Paul Lakowski, the difference in performance can reach as much as 8%[9] 3.25 kg of Composition A-3 (M393A3)