It's been a while since I checked out the Tromix website, but after reading MadOgre's reference to the chopped down 12.5" barrelled "entry" Saiga recently I thought I'd better have a look.
Glad that I did- they have a folding stock AK-47 rechambered in the massive .458 SOCOM- basically giving 18 rounds of .45-70 power in a very compact and easily reloaded format. The SOCOM AK can kick out a 300 grain Barnes X-bullet at over 2,000fps. Corbon are currently offering a 450 grain load and a 600 grain load. The latter loading can give 950 fps.
The SOCOM AK is billed as "capable of dropping some of the largest game in the world".