I have a problem with one of my model 400's. Both of them are the later production style with adjustable trigger and without the loaded chamber indicator. One rifle feeds smoothly and reliably. The other tends to hang and is prone to jamming. Close inspection revealed that the breech end of the barrel protrudes into the breech block just a tiny fraction of an inch. This causes the feed arm to catch and also probably causes pellets to jam sometimes. (The barrel and block on my other 400 are flush, no problems with it.) Can the barrel be shifted forward a bit in the breech block? If not I may have to grind or mill the barrel flush with the block. I got this gun for my younger brother and would like it to be in good working order when he gets it. Any advise much appreciated.