4seventy:

I read Wright's book long after having done load development in .450/.400 3 1/4", .450/.400 3" and .470 and and seem to remember being surprised at some claim he made about Kynoch ammo in the big nitros running way below listed velocity, as this had not been my experience at all. Did he say 80 to 100 fps? I liked his book so much that I gave my copy away. Your reminding me of this prompted me to go find some of my old notes.

When beginning load development in any particular nitro double, I always fired original Kynoch in it to establish a base line. I was impressed at how predictable the old Kynoch was relative to listed velocity and two variables, barrel length and priming compound, in all three calibers. Corrosive primed Kynoch from the '50s was consistently 20 to 40 fps faster than non-corrosive stuff from the late '60s and early '70s (Original Kynoch ammo is marked on the box with a date code showing month/day/year). Corrosive stuff usually ran right at listed velocity in 28" barrels (as mentioned, standard velocities were usually taken from 28" barrels, sometimes even 30"). It was my impression that Cordite was particularly sensitive to barrel length. Shorter barrels gave slower velocities as expected - seems to me to be roughly 25 fps loss for 2" of barrel.

Here are a few samples.

Watson Bros. .450/.400 3 1/4" (listed vel. 2150); 28" barrels.
Corrosive, 1953 -----------------------2141
Non-corrosive, 1968 ------------------2105

Wilkinson .450/.400 3 1/4"; 24" barrels
Corrosive, 1953 -----------------------2094
Non-corrosive, 1968 ------------------2060

Hollis .450/.400 3" (listed vel. 2125); 26" barrels
Corrosive, 1956 -----------------------2094
Non-corrosive, 1972 ------------------2070

Rigby .470 (listed vel. 2125); 26" barrels
Corrosive, 1956 -----------------------2110
Non-corrosive, 1972 ------------------2076

I've never had the occasion to try original Kynoch in a .450 3 1/4" but I have no problem believing that Kynoch from the old days (the corrosive primed stuff) actually gave 2150 in the 28" barrels that many of the original .450s had.
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