'olBEAR' - Welcome to the KCA Forum.

The 'Hinge Bar' (of the Krag Magazine-Gate) is suppose to remain closed and cover the cam and contact surfaces of the Follower-Arm Assembly.

It is intended to be easily opened by lifting the flat (spring like) cover, while rotating the Hinge Bar. This is to facilitate cleaning, inspection, and light lubrication.  IMHO - It is best opened with the Stock removed from the action.

The condition you describe ('self-opening') is a common Krag affliction.

Several things can cause this problem: old dried up crud and grease, burrs on the long 'pin' part of the Hinge-Bar, including its tip, lack of lubrication, and a bent Hinge-Bar, especially near the cover. Often all of these factors are present.

My advice is to disassemble the Magazine-Gate assembly. Remove any burrs and straighten the Hinge-Bar, clean dirt & old grease, and lightly lubricate parts.

While still apart (and without the Follower/Gate Spring), test the alignment of Hinge-Bar with the 'loops' on the receiver and test its fit through the 'long hinge hole' of the Loading-Gate for freedom to rotate. The flat cover on the Hinge-Bar needs a bit of tension to lock into place in its recess on the bottom of the receiver.

'olBear' - The curved flat-spring ('R' on the schematic) puts considerable pressure on the hinge of the Magazine-Gate.

The tension on the spring can be reduced to a degree by removing the left Side-Plate. This relieves the tension of the follower-assembly.

A soaking of penetrant on visible areas of the Hinge-Bar and Magazine-Gate hinge will make disassembly easier.

Do not use excessive force. The Magazine-Gate needs to be held in position, while the Hinge-Bar is slightly rotated, 'back and forth', while at the same time pulling it forward out of the Gate.

(Caution - Do not use a 'punch' on the end of the Hinge-Bar to drive it out. This will deform it and cause problems).

I have a strong grip and can hold the Magazine-Gate in place, while withdrawing the Hinge-Bar. Sensible people use a padded "C" Clamp, to hold the Magazine-Gate in place on the receiver, while withdrawing the Hinge-Bar. 

I didn't have to take the hinge pin out after all. The little trap door thingy was all boogered up and bent. A little needle nose work and brass hammer tapping straightened it out enough to snap back in place.
Thanks for all the help.

olBEAR aka BEAR