Krag Trigger-Guard screws: My practice and rationale .... I could be delusional. (I am willing to learn a better method).

I want my Krag receiver to sit 'flat' on, and support, the thinnest area of the stock. I want my barrel to lay on the bottom of the stock barrel channel. I want to see a 'sliver of day light' between the top of my barrel and the inside of the front barrel band. I want the rear of the magazine 'box' in contact with stock wood.

When I assemble my Krag, I position the barreled-receiver in the stock, put the rear barrel-band on loose, and hand tighten the front guard-screw "Tight".

I then tighten the rear barrel-band so the sling-swivel is tightly pinched, but movable.
I assemble the front barrel-band observing that the barrel has not lifted up from the stock in the muzzle area..

Lastly, I put the rear guard-screw in, making it just firm.

IMHO - The rear screw can do mischief.

It can torque the barrel up off the channel.

It can cause the receiver tang to pressure and spread the surrounding stock wood, like a 'wedge'.