Assuming that take-down on the M1A, commercial M-14 is the same as it was for The Garand (M-1), try the following.
1. remove trigger group. the trigger guard locks same to the rifle, and pivots, hinge is at forward end.
2. remove barreled action from stock. with a "lug gun", is that what you have??, rewmember the guard screw(s).
3. dismount operating rod from rifle.
4. at that point, you can move the bolt with your fingers, and it comes out quite easily.
Hope my memory serves, and that the foregoing helps. BTW, check to see that rifle is unloaded. Surprising, what people sometimes forget.