Lynda; I would suggest only shooting standard velocity in it, there are some problems that might happen with high velocity. I have only found 2 variations in this model, early guns had a forearm with a screw on each side and late guns had two screws on the right side only. Here's some more info - Old Savage Pump 22 - RimfireCentral.com Forums Would appreciate seeing pictures just in case it has some variation I haven't came across yet.