The OP posing an interesting question on the relative accuracy of the 52 barrels over the period of manufacture. I think the main reason there is not much information from shooters is the changes to the action, triggers and stocks. A's and pre-A's only had one action screws and the left wall of the receiver being cut down does not help rigidity. The B models had better triggers, but not as good as the later C, D and E models. Stocks started out looking similar to a 1903 Springfield and ended with the International series of stocks. Stock design makes a lot of difference on the ability to shoot smaller groups, as does chambering reamer design which also changed later on. Winchester reported accuracy of the different models as production went on, but with different model actions, triggers and stocks using different ammunition as time progressed. It would be an interesting experiment to fit a good looking barrel from each of the models to the same late D or E action with a light trigger, bedded in a BR stock and compare accuracy. It would be the proper way to test the relative accuracy of the barrel only; and to achieve accurate results, you would need use several barrels of each vintage to get an average. I somewhat doubt it would ever be undertaken, considering expense and having to procure the necessary barrels which would no longer be original after having been refitted to another action. Plus while the results would be interesting, it would have no practical information gained, as most shooters would still use the barrels that came on their specific models.