... The non-tapped holes in the B&S set are 0.376, in the Chinese set are 0.357. The threaded holes in both are 3/8-16.
Obviously the Chinese set is not made correctly, and the B&S set will bolt together as they should. Another example of cheap import tooling following the form but not the function.
Alas, B&S's current offerings have the same problem that the Chinese ones do. I have a pair of US-made Suburban blocks that do have the correct hole sizes. If you check around on eBay you can also find a lot of machinist-made 123 blocks that are quite good, and have various hole configurations. TNGtool and MachinistBox are two sellers in particular that have some excellent stuff.
Note also that there's nothing magic about the 1-2-3 size. I have four very nice blocks with one hole each that are .5x1x1.5, and those are a great size for my Taig mill.
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