Mouth - Prewar Post War

Some believe that a tight mouth is an essential feature of a smooth plane to reduce tearout. Others think that setting the cap iron extremely close to the end of the cutter is very important, and mouth size has little to do with tearout. While the A17 is noted for its fine mouth, prewar Norris 5's and A5's can come with an extremely tight mouth. Some suggest that many users opened the mouth once they got the plane to reduce shavings getting trapped in the mouth of the plane. On my most recent acquisition, the bed of the plane and the original iron both are marked with a 7 suggesting this iron was fitted to the plane. I can confirm that the mouth opening is extremely fine - so much so that on certain woods it does exhibit some choking, though not bad enough to make me want to open it up. The Post War Norris planes have a much wider mouth. If a user want to make that mouth finer, he could insert a shim under the plane iron, or try to obtain a thicker iron, either parallel or tapered. The photos show that the difference in mouth openings of the prewar and post war are pretty significant. The top photo shows a clear image of green, which is below the iron, on the prewar plane the green is practically invisible. In the bottom photo it is easy to get confused by the mirror image that is honed on the iron on the upper plane - but when you ignore that, you can hardly see the green which is on the other side. In the lower photo, the green is easily seen.The photo of the sole shows that the Post War hit some metal - which left a groove on the sole - it looks worse that it is.