[mrerick]

The OP's Luger (assembled from two donor Lugers) may need some attention to hand fitting and lubrication.



There were a range of recoil mainsprings used on a variety of Lugers, and we have the table in the Luger FAQ PDF document available on this site. It lists them by wire size and coil count.



If there is any variation in the way the slide or toggle train movement cycles between sloppy loose feeling and tight binding, this could relate to fitting problems. Some detailed attention to how the action feels as it cycles without the spring in place might be useful. Also the tape test on the back of the frame to see how hard the toggle heel impact is on the frame.



I would address the hand grip and grip support first. Then start looking at the precision fitting of parts being smooth and properly close. Then perhaps the recoil spring.



The Luger has a precision balance in it's action operation, and many things can disrupt it.