sorry for the dumb two part question
im search-deficient

1.    Has an AR15 been built in the russian 5.45x39?

2.     Would 5.45 rounds feed from 5.56 magazines?

the reason i ask #2 is:  
                                           some of the Saiga people converted their .223 Saigas to feed from                          
                                            inexpensive AK74 5.45 magazines -

so im wondering if it would work the other way around


i apologize in advance if this should be in the AR variants section    

Yes.

No, but sort of yes. 5.45 converted magazines are iffy and need feed lip manipulation.

My question. Why? 5.45 sucks from a terminal perspective and the only ammo I ever found for my SAR2 was Wolf, Barnaul, Silver bear... I can get 5.56 Wolf for cheap if I want crappy blasting ammo.

no reason really

i was just asking out of curiosity
as i said this idea came from people using 5.45 mags for 223 in Saiga rifles