We've already discussed the matter in
this thread, but here's the gist of it:
The order places Concern Kalashnikov and Izhmash on the Specially Designated Nationals (SDN) list. That means the importation of their products has been banned. It's rare for these orders to be rescinded, even by later administrations, so it's probably permanent.
The order is perfectly legal, and if we're going to levy sanctions against Russia, weapons exports are a vulnerable segment of their economy. This was done for reasons other than just antagonizing gun owners.
In practice, the only difference American consumers will see is a lack of Saiga firearms on the market. Prices have ballooned and availability has declined on those over the last year, so the order really doesn't do all that much. Most of the "AK-47" type rifles on store shelves are Romanian, Bulgarian, or parts guns assembled stateside. Those aren't affected.
The order doesn't restrict Kalashnikov/Izhmash products bought or imported before it was signed, so old inventory can be sold.
Now, will the sanctions have any effect? I doubt it. Sanctions are meant to inflict economic pain and to deter a rogue nation from doing naughty things. Without the support of Europe, these are relatively insignificant. Furthermore, a man like Putin is unlikely to be cowed by this. We've been to this rodeo before.
Still, this is what politicians are expected to do in a case like this.