Because of throat/groove dimensions, many .303 Lee's don't perform well with boattail bullets. Furthermore, at 200 yards you don't need either the weight or BC of those 174's. Try working up some loads with a ~125 grain flat base bullet or a 150 grain FB like the Sierra spitzer soft point (#2300). These will kick less than 174's and may group better.

For a longer-range load that comes close to duplicating the Mk7 trajectory for which the sight is graduated, I like the Sierra 180 FBSP (#2310) with maximum 42 grains of 4895 in my Lithgow (fuzzy :( pic attached).

Don't assume the .303 will take the same handloads as the 7.7 Arisaka, which has more case volume and a stronger action. Maximum loads run about 3 grains lighter for that SMLE.

PM me if you have trouble finding brass or chargers (but only if you promise not to write "stripper clip" again :-/).

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