If it's an ejector, it won't make any difference on a rimless cartridge like the 25-06, but an extractor will. Which is it? If it's an extractor barrel, you may be able to use a spot of JB weld under the extractor post to control headspace, I've not done it yet, but have thought about it. When I fit a barrel, I flat file the chamber face so the sized case is flush with the chamber face, not recessed. It may be best to send it to H&R for replacement if it's a factory fitted barrel.
Tim