I want a little better grouping out of my ak.  I am a big guy and could use a bigger length in barrel and stock

(dont you love those chineese stocks...  Ya Ill take 2 Please.  One to S#!t on and one to cover them up with)

I want a better ranging wheapon!  

Maybe you could buy an RPK and put AK-47 style furniture on it if you've got to have the "AK look". You'd end up with a longer barrel, longer USA stock(if you change it), and a farther effective range.

Or just leave the RPK alone and enjoy as is.

Not alot you can do to improve the AK's barrel as of yet (though I've seen some tinkering on here with good results).

If you're thinking along the lines of an AR-15 with bigger badder barrels and 5-million-and-one configurations STOP IT, you'll only be disappointed. IMHO AK's were meant to be enjoyed as-is, but with some training it's a very effective weapon. It even makes an idiot shoot OK.

Look around for either a Chinese NHM-91 or a Maadi RPM.  Both have 20" barrels which are longer then normal AKs, but not quite RPK length.  

Get one of those, then get an extended length AK stock from K-var and you will have a weird AK that will fit your bill.  

The heavy gas system riding on an AK's barrel will pretty much always prevent any sort of "match" accuracy in a barrel, so you can forget that.

One cheap interim choice is the $7 rubber butt pad extension (tapco is only source I know) that adds at least 1" to your stock length.

Better ranging weapon? Over what distance?

Little better grouping may also come from trigger and sight work.

The weight of the VEPR and SAM7 seems to pay off in nice group reports. Hanging the bbl off of a more solid receiver does not seem to hurt.

But 4moa is good for many 7.62x39 AKs, and beating 3moa seems to require a smallbore AK.