If you have a 14" twist barrel you could try some other bullets up to about 100g. A 14" twist won't stabilize anything much heavier. Have you tried any other powders/bullets.

Some barrels are just picky about certain powders or bullets.

I have an old 99TD in 250sav but I haven't loaded for it in over 20 years. It was my great grandfather's who bought it new in 1917. It will be my daughter's first rifle when she is old enough.