It depends on combat conditions. Are you taking fire? Are you hiding behind a concrete barrier with enemies moving around you? The variables around you are going to determine your course of action. If you can quickly and safely remove the jammed round - without exposing yourself to oncoming tangos - great, do it. But if you're in a firefight, removing the jam in the weapon then & there is probably not the best idea. While you're fiddling with the weapon, the enemy is still engaging and your eyes are on the weapon - not your surroundings.
On the flip side, the jam is where the round is not being chambered correctly. This could be from dirt/debris/contaminants on the inside of the rifle, faulty equipment (improper design of the rifle, or the round) etc. Without seeing the actual rifle, it's hard to determine exactly why the rifle jammed, and thusly how to proceed. In general, the M1 was an excellent rifle - I have one that landed on the beaches of Normandy. When you take care of the rifle with proper cleaning and maintenance - even in combat zones- it'll take care of you.