marlin 20a breech bolt

[bobinpa]

In October of this year, I asked for help to identify a part needed for a marlin 20a. I purchased parts from gunbrokers.com for a marlin model 20. I was told that the parts from a model 20 and a 20a were interchangeable. I can not get the 20a to accept the breech bolt from the model 20. Are these parts interchangeable? If they are is there something else I must do to insert the bolt. Also what does the handle slide connect to in order to use the pump action. thanks in advance for any info...........bob