From what I can tell from reading many of the excellent posts by Marlinguy and others most (all?) #2 Ballards were built on forged actions.  I finally had an opportunity to pull the forend off my recently acquired rifle to confirm that it had the hollow area under the barrel threads indicative of the forged action.  I thought I would share a picture of it in case anyone had any comments.  I think I was expecting a larger hollow area than what is actually there.  The forearm has a projection that fits into the hole.  Is this indeed a forged action or is possibly a different model?  Serial numbers on the barrel and receiver match and it appears in very good condition.  Bore is "minty", as some collectors like to say.  I haven't had the chance to remove the breach block yet to look for the rough interior of the cast action, but what I can see from with the breach block installed it appears to be relatively smooth.

THOP

Thop,  the hole you are looking at is not the hollow being referred to.  In order to see the hollow, you must take the breechblock and lever assembly out and look forward under the barrel tenon.   

Also, the hollow is a characteristic of the cast, not the forged action.  All of the #2s I have seen did indeed have the hollow and were indeed cast, FWIW.

Don't look for the inside of a cast action to have large pits and craters, it just is not all machined surfaces since the non-bearing areas could be cast in.  Hope all of this is of help to you identifying your Ballard.

Green Frog

Well I see a couple of regulars also replied while I was writing, and I don't have one at hand to check, but I think you can see enough to tell without removing the breechblock.  

cast and forged

The quick way to tell that has so far worked for me is that all forged actions seem to just have a two line address and the cast actions have a three line address. 
Mike

Westener, now that brings up a good point. It makes one wonder just what type of presure one needs to blow one of these. I'm like you, I would have to say something was in the barrel or chamber to due that much damage. 
Mike

I took a the opportunity to pull the breach block on my #2 today and confirm that it is a cast receiver and look for the serial numbers.  I confirmed it is indeed a cast action as the attached pics will attest.  I was also pleasantly surprised all the parts had matching serial numbers.  Now I just need to put to work all of the great information I received from everyone and build some 38 cartridges.  Thanks to everyone for their input.
THOP

Sorry mwhite49,
My dislexic brain turned that around. But I'm still going to stick with it being flawed. The #2 I have is a forged frame, with centerfire only breechblock, all matching numbers, but a three line address. It is chambered for .32 Ballard extra Long, and has double set triggers. It's a very early JM Marlin Ballard.
Generally speaking it is true that forged will have two line addresss, and cast will have three, but there are always exceptions. When I bought this #2 it was advertised as a #4 Perfection, but John Dutcher identified it as a special order #2 with forged frame.