Is it safe to specialize in automatic weapons from the start?

Yes, specializing in only automatic weapons is perfectly reasonable. You will be able to pick up a rusty AK-47 fairly early in the game as they're pretty commonly found on bandits.

You can find a rusty AK fairly often in the smuggler's shop in the sewers of Krasnoznamenny, which requires a 1000 fee to enter (can be cheaper/free if you pass the skill checks), and a thief's pass to enter the smuggler's area, which you can get very early on.

edit Previous trick is no longer doable. Left in spoilers in case anyone's curious

There used to be a way to beat the bandits in the beginning of the game to keep the ak-47 but that's no longer doable.

I've only played it once because there's basically no endgame. You'll be done with the game before automatic weapons come into play. It has game mechanics and character creation similar to Fallout, but its world is lacking in locations and the random encounters are trite.

Equipment offerings are a little too sparse to put points into anything that doesn't help you cook, heal yourself, or wack people with shovels. All guns go to your companion who can actually hit with them.