Trim your patches down 1/4" at a time until they go through more easily. Some patches are made of thicker material than others which can also pose a problem. In that case you might try a 7mm jag with the full uncut patch just to see how that is.
Also, make sure you run a wet brush through the bore a couple times before trying to push a patch through. Trying to get a patch through a dry dirty bore is always a challenge.
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