Rossignol ENT
The Rossignol ENT was an experimental automatic rifle of French origin from the first years of the 20th century. It was the first rifle which used the direct impingement operating system, which found later use in the Swedish Ag m/42, the French 1940 MAS and, most notably, the AR-10 and AR-15 series of rifles. Rossignol developed the new impingement system, and modified the Friberg-Kjellman system of opposing, retractable bolt lugs for this experimental rifle. The rifle was produced under the École Normale de Tir, thus the ENT designation, and was produced in at least four variants, "ENT No. 1 or B1, B2, B4, B5". Specifications
 Cartridge: 6×60mm
 Caliber: 6mm
 Weight: 9.7 kg
 Operation: Gas direct-impingement

References

Further reading

 http://i2.guns.ru/forums/icons/forum_pictures/000643/643512.jpg

Light machine guns
Automatic rifles
Machine guns of France
Trial and research firearms of France
Weapons and ammunition introduced in 1900