Stihl bar dilemma

[Mozzer]

I have a Stihl MS260 with a 20" bar ref: 3003 008 6621. That bar is really worn but finding a replacement of same spec seems to be difficult in Canada. I can see options for 78 or 81 link chains/bar with thicker gauge chain (0.063 vs 0.50) but I have 3 new spare chains of the original spec, these chains (80dl, 0.325, 0.050) are not as easily available now either.
Can I get by with a slightly different bar type 0.058, 81 or 78 dl for example & use up my chains before ordering new to suit that bar? Time is a factor as I need firewood but can't cut anywhere near straight anymore (bar is original from ten years ago).

 

[J D]

If you run your .050" chain on an .058" or .063" bar it is unlikely to cut very straight & won't do the bar any favours either.
Have you considered dressing your existing bar & closing the rails to spec... that may allow you to use your existing chains before replacing it.
Some good pic's of your existing bar & chain may help us provide more advice