Another option if you want to have a go is paper patching undersize bullets up to the size you want. I have an old 1895 Winchester in 303Brit that I paper patch for as it's barrel is .317"! This rifle has won quite a few competitions for me & will shoot 2" groups at 100m with these which is pretty good for a rifle this age & with these barrel dimensions.
Hope this is of help.
Cheers.
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