Mausingfield m7 bore guide help

[SSzelong]

I have a 300NM Mausingfield m7 and I’m trying to buy a bore guide for it. I’ve used possum hollow for other rifles in, but I can’t find a model number for the 300NM. I made the mistake of ordering a Piercision rifle bore guide with an OD of 0.743 and it doesn’t fit the Mausingfield. Anyone have a recommendations?

Thanks
Scott