I bought one last weekend because it is in remarkable condition and unusual. It is a semi-auto that will accept .22 Long, Long Rifle and High Velocity Shorts. The guy I got it from said I could "adjust it out of the stock underneath" to use either LR or Shorts. Well, I don't see any adjustment "places" but the shooter can lock the bolt closed or open. I need someone who is familiar with the rifle model to explain how it operates. It is having a little trouble cycling even after a cleaning and I think it may be "out of adjustment" or gummed up in a place I haven't found. Any information will be helpful. Thanks.