The CZ550 is a timeless classic and a top choice for a .375 I find the barrels bit long and have cut them back to 21" which works well. Zastava rifles are a good choice, as these are a Mauser clone.Some of the stocks that Zastava have sent out are a bit rough though , so you would maybe need to get a replacement stock. But don't let that put you off. Charles Daley uses Zastavas and they seem to have decent stocks.
When you take an A-Bolt out of its stock and see all the rods and pins held on with C clips you will see why I would avoid a .375 A-bolt. Infact I have taken non magnum A-bolts out of their stocks and heared a ping! as some part of it has dropped on the floor, then spent half an hour on my hands and knees looking for it!
You could always pick a Mauser actioned rifle up and get a barrel from Midway and build your own DG rifle.
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