Fred-
When determining wind drift for a given caliber several factors need to be considered, such as velocity (muzzle and at target); bullet weight and nose form. This is usually expressed as BC. Also wind drift is normally calculated at a right angle to the line of flight. I have done extensive testing with many weight and nose form 32 caliber bullets and some preliminary testing with the 25 caliber. My test equipment allows me to capture both the muzzle and target velocities. The following data is based on actual test results. Wind drift based on 1 mph cross wind.
32-200 grn. Flat Nose meplat=.100; MV=1479fs; 200yd=1191fs; WD@100yd=.241; WD@200yd=.979; BC=.310; retained velocity=
80.5%
32-205 grn Spitzer 4.5radius nose meplat=.045; MV=1478fs; 200yd=1196fs; WD@100yd=.219; WD@200yd=.890; BC=.341;
retained velocity=81%
32-215 grn Spitzer 4.5radius nose meplat=.045; MV=1478fs; 200yd=1219fs; WD@100yd=.208; WD@200yd=.845; BC=.359;
retained velocity=82.5%
32-205 grn Spitzer 5.5radius nose; metplat=.045; MV=1486fs;
200yd=1219fs; WD@100yd=.209; WD@200=..850; BC=.355;
retained velocity=82%
32-215 grn Spitzer 5.5radius nose; metplat=.045; MV=1488fs;
200yd=1239fs; WD@100yd=.197; WD@200yd=.802; BC=.376;
retained velocity=83.3%
32-215 grn Round nose; MV=1486fs; 200yd=1221fs; WD@100yd=.218;
WD@200yd=.887; BC=.341; retained velocity=82.%
25-108 grn Spitzer 5.5radius nose; meplat=.030; MV=1480fs;
200yd=1164; WD@100yd=.254; WD@200yd=1.030; BC=.290;
retained velocity=78.5%
As you can see the retained 200yd velocity increases with the efficiency of the nose form. A comparision of adding 10 grains weight can be seen with the spitzer bullets. The retained velocity % and BC remain constant so long as the bullet is stable in flight and the nose follows tangentally to the trajectory arc. Casting a bullet in an alloy that changes the weight of a bullet will also change its RVel and BC. At my current stage of testing the 25 calibers I have only worked with the most efficient nose forms. Flat nose and round nose bullets can be expected to have less efficient ballistics as with those indicated with the 32 calibers. My experiments indicate that increasing the nose ogive radius beyond about 6.5 calibers causes a decrease in preformance, probably due to nose slump.
I hope this is of some help Fred
7~