Good eye 'madsenshooter', it does look like the last digit "8" was re-struck with a "9".

I knew #225698 was in the range where model 1899 carbines started being made. I guess 'Dutch51' actually has a model 1899 (overstrike) carbine.

I don't know the story on these 're-strikes'.

It is comprehensible that if Springfield had to turn out a block of model 1899 carbines in August-September, 1899, some 'model 1898' receivers in the parts bins, might get their model date changed.

I still think the barrel is a likely replacement made from a cut-down rifle barrel. If a good carbine barrel had been on this receiver, there would have been no reason to replace the front sight base.