Ouch!!!!.That is one poor Tornado:(.Grumpy just said it all!Rebore or SH barrel Mark:)Id not dare tell you what not to try,BUT...Sanding is only gonna make it even bigger,Blow by will be massive and while the rings might feel they are giving compression when you first fit them,after the first run it will be just about gone:(Its a good model and maybee worth spending a couple of dollars,get the bore OS and do the rest yourself?Good luck:)