Barrel lock-up on B19

I have a B19 and I can't get it to group well at all with a scope. The group is spread in a verical line. The barrel does not seem to lock closed very tightly and it appears as if with each shot the barrel is in a different verical position, ie not closing to the same postion each time. I can feel it moving when I apply pressure to the barrel when it is closed.

Is there any way to adjust anything to get it to lock up more solidly?

Otherwise I am quite happy with it, I gave the internals a good lube with moly grease and it cocks smoothly. Shoots accurately enough with open sights.

http://www.funsupply.com/airguns/barrellockup.html
I don't know the author, but the info is pretty sound.
Jack

Thank you, I thought that my lock-up was poor because of too much lube and I dried it off.

I think the fixed lug needs a little work so that the spring loaded lug in the barrel can grab onto more of it.

I had the same problem with my B-19 about a year ago. The bushing in the breach was WAY to loose, I had to make another bushing . After I done that my problems were solved.