Ahhhhh yes the ripper gun, from what I recall of the fluff about it it's pretty much an auto Shotgun that fires extremely large sheels much like a 50cal, and doubles as a melee weapon. Fantastic bit of kit.

If I recall correctly, a major part of that fluff is that Rippers were made especially sturdy (and may, in fact, be the only weapon capable of withstanding an Ogryn's (ab)use, given an Ogryn's more simplistic concept of combat, in which different weapons for different occasions might be a bit too advanced for all but an exceptional BONE'ead.

I love Ogryns. Ratlings are fun, too.

I would probably give them Intelligence 10+2d10 and then give them no Intelligence increases (like the Tech Priest and Fellowship).