Interarms Mark X - Adjustable trigger

[Warners]

I recently bought a H&R Model 340 rifle from the mid 1980's in unfired condition. Without checking the screws that hold the action into the stock, I went out and fired 40 rounds through it. Well, either due to the loose screws or an improper fit in the stock, the stock developed a crack and I'm going to replace it. I remember reading about some of the Mark X's having adjustable triggers, and then quickly forgot about it. Well today when I pulled the action out of the stock, I saw a couple of screws on it that look like they'd be for adjusting the trigger. So my question is, how do I adjust it and what do the screws actually DO?

Thanks in advance,

Warner