There is.

It’s just not called the AK48 because it wasn’t introduced in 1948.

In 1959 the AK47 was updated, changing from a heavy, expensive milled receiver to a lighter, cheaper stamped one, along with a few other changes. This improved pattern entered service as the AKM or Modernized AK.

In 1974 the AKM was updated, rechambering it from 7.62×39 to 5.45×39, and a few other changes. This was the AK74.

In 1995 the Izmash armory introduced the AK101 and AK102 chambered in 5.56NATO. In 2001 they offered the AK103 and AK104 in 7.62×39 and AK105 in 5.45×39.

In 2017 to 2018, Kalashnikov Concern, formerly Izmash, offered the AK12, AK15, and AK200 series, and finally the AK19 in 2020.

And this is without looking at the myriad copies produced outside of Russia.

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The AK-47 has been updated many times. Just not in 1948, hence why it’s not called the AK-48. It’s called the AK-74, because yup, you guessed it, it came out in 1974.

There’s also the AKM which came out in 1959,

The AK-103 that came out in 1994,

And tons of variants like the Type-56, the AKS, AKSU, etc.

That’s not even a comprehensive list of all the updates the AK-47 got. I’m not exactly a gun expert. Everything I know about guns I learned from Lloyd’s Weapon Mod. There were like a dozen types of AK’s in LWM back in the day and I’m sure it wasn’t even all of them.

So yes, the AK-47 was so good it spawned an entire family of assault rifles.