I've just bought an M48 in .223 but I don't have any information. Ive tried to contact Nosler but haven't had and response.
Can anyone help with the barrel twist rate and year of manufacture? (Serial number is N1988)
Welcome! I cannot answer your question, but I suspect that calling them will be the right way to go. Fortunately, there are many people here much more knowledgeable than myself (not to mention better spellers), so perhaps one of them can provide a more complete answer.