The older factory is IZHMASH, which was founded in 1807.
Although The first batch of AK-47s was produced at the Izhevsk Motor Plant
At that time it was called the Izhevsk Ordnance Plant. The Izhevsk Ordnance Plant has by now evolved into the Izhmash JSC. So we're probably splitting hairs arguing over making them different plants, but they were different at one time. My video on the full auto forum clearly shows an Izhevsk product (AK), with the older insignia. Although I mistakenly refer to at as "Tula" ( I was a bit excited over shooting it)>
So it is an arguable point.
In 1942 the Soviet State Defense Committee adopted the Decree #622, by which IZHMASH (the Izhevsk Machine Engineering Plant) was restructured. A part of IZHMASH's production (pistols, revolvers, anti-tank rifles and later - shotguns) was separated to launch a new and an independent productional facility - the Izhevsk Mechanical Plant, or IZHMEKH (Russian: <Ижмех>) for short ......and were responsible for the production of small arms, particularly pistols; even to this day, though fighting over the trade name of Baikal continues.