Years back I found a Molot 10 round 74 mag, it is ribbed and has a molded in plastic baseplate. it is marked 5.45 and has 3 silver acceptance stamps on the RH side top.  Recently I picked up another 74 10 rounder on GB for cheep, has the Izzy? triangle and arrow, marked 5.45X39, looks like a shortened OEM mag, problem is it will not lock into either of my 74s. Holding them sie by side they look to be the same, have'nt miked them out yet. What do I have?

FOLLOW UP! After a quick compare of the 10 rounder with an E. German bakelite, the difference is above the front locking lug, several minutes with the Dremel and this thing locks up tight and feeds dummy rounds like no tomorrow. Will have to take to the range today an see how it performs.

Can you please post some photos of your bakelite 10rd mag?  Thanks

That is because it was made for a Vepr without a bullet guide and the front of the mag has a bump to act as a bullet guide. Grind it and you are good to go !
They made 5rd mags also .

My E. German bakelite mags are all 30 rounders! I was comparing the Siaga 10 round to my E. German 30 round as a reference point on what to dremel away! Mag feeds and functions great in both my 74's.