I had asked this over in the AK forum but didnt really get an answer.  Has any ever converted an sks from 7.62 to 5.45?  Id really love to do it.  I can get a decent quality sks from a local dealer (the same one I got the K31 for $59) for pretty cheap.  Id love to rebarrel it.  I'm sure I can wangle something to get the sks 7.62 mag to feed the 5.45.  They are not too different.

IIRC, your question was answered.

The SKS was not designed for that caliber.  It would require a rebarrel and trunion job. Since this would come from an Ak, it would have to be customized.  Then, the gas system is not set up for that round, (nor is the AK trunion and gas system) so you would have to tweek it  a lot so it would work reliably.

The mag issue would be the least of your concerns.  

This has been asked many times, and the general idea is that for the cost and time involved, it is not worth it.

I personally would contact Ohio Rapid fire, or Inrange, maybe AK-USA.  They are about the best around, they would be able to do it is anyone could.  

Hope this helps.  I am just waiting for a nice bolt gun in 5.45 from Remington or Savage would even be acceptable.

Ok, is there any full size semi 5.45 rifle available then?

Only the AK's and the East German bolt action  sniper SSG-86 that were crap.

I think they are making RPK semi-autos in this caliber though. Big and heavy. Probalby not what you are looking for. Not cheap either.

The 5.45mm uses some odd diameter bullet, doesn't it? Were it possible to get the right size barrel blank and a 5.45mm chamber reamer at reasonable prices, I don't think it would be all that hard for a good gunsmith or machinist to convert a threaded-barrel SKS. The gas system looks pretty slam-bang to me, not like it requires super fine tuning to function. I'd just start with a small port and keep enlarging it until it worked.

I'm sure Clymer could make a reamer, if you threw enough money at them. The barrel blank might be a bit harder to get.

I guess if you had to pay for these things, then pay somebody else to do the work and not even have the fun of doing it yourself, the whole project really wouldn't be worth it.