rw
this is the original question? correct?
Speer #8 has data using a S&W Model 27 6 inch
and for 2.5" barreled Colt and S&W's

the bullet used for both are their 160 gr. soft point - it has a different shape than OP's bullet - but its of use in a comparison using the exact same bullet for both of their tests

6 inch data
15 grains / 1280 fps
14 grains / 1204 fps
CCI 550 magnum primers were used

2.5 inch barrel
15 grains / 1199 fps
also used CCI 550 magnum primers

from my experience....magnum primers add 50 fps in my 6 inch 686

so subtracting 50 fps
6 inch
15 grains / 1230 fps
14 grains / 1154 fps

2.5" barrel
15 grains / 1149 fps

OP used 14.5 grains and a 4 inch barrel

1037 and 1114 are a little low but
It seems to me his velocities are in the ballpark with the manuals, and considering the manuals are usually optimistic.

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I'd like to agree with you BUT