This is a quote from Tim, and I've done the exact same thing and it's worked a time or two. Actually, the pin came out easier than expected. It still wasn't a cake walk.
"The pin is generally very hard to remove, all of those I've removed were, you can use a heavy hammer and brass drift, backing the frame with an oak board on a concrete floor is how I've done it, but an arbor press would be better, no worry about smacking/scratching the frame!"
I don't mean to sound like a slob/snob when I say this, but I keep from two to four spare SB2 frames always. When I encounter a problem, I change frames. Ninety percent of the time the problem is cured. Don't ask me, cause I'll have to go and count, but I think there are fourteen Handi Rifles, all totally unaltered (barrel shortening excluded) locking up tight and shooting well. There used to be shims living here, but there ain't no more.
Pete