leelee:
There are two adjusting screws available, each with a locknut on it. The screw at the front of the housing is for adjusting let-off weight, and that at the rear is for adjusting the trigger/sear engagement. There is no over-travel adjustment screw.
The spring under the weight adjustment screw is trapped – it is larger,in diameter) than the minor diameter of the screw hole. Even with the screw removed completely, the spring remains in place and is quite heavily loaded, limiting the lightest let-off weight that can be achieved.
The factory book with my Weatherby Vanguard rifle,which has exactly the same action, re-badged) warns against altering the engagement screw, but it can be done. Turning it inwards reduces trigger/sear engagement, and hence pre-release movement of the trigger piece, or ‘creep’ as it is more often called.
Turn the engagement screw too far in, and the safety catch will no longer engage. Turn it in MUCH too far, and it will be impossible to cock the rifle – the striker will simply ‘run down’, same as if you close the bolt with the trigger already pulled.
If working with the adjusting screws doesn’t give you the performance you are seeking, some modifications of the trigger unit are possible. However, unless you are thoroughly conversant with the principles of over-ride triggers, and have the workshop equipment required to enable you do very accurate cutting of hardened steel components, it would be best to have this sort of work done by a professional gunsmith. There is only a small margin between improving the trigger pull and wrecking the whole unit – or leaving it so that it still functions, but is far from safe.
Timney make a replacement trigger unit for this rifle which is fully adjustable for weight, engagement, and over-travel. I have heard favourable comments about this unit, but have no first-hand experience with it.