With a 3 o'clock 5mph wind what is the estimated drift for these loads at 200 yards:

.22 rimfire MV 1050

.25 100 grain bullet, typical schuetzen velocities

.32 200 "                 "

Thanks for helping.

fred

.

If a wind was fairly consistent the smaller calibers may not be that much of a problem offhand. I looked at the scores from the ISSA shoot at Raton last year and one Matt Taylor was in the top 10 offhand with a rimfire, I understand conditions were very difficult and he shot a
1023.

fred

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~ 

Well here is my opinion and to put it into perspective I shoot a .22 rimfire, 32/40, 38-55 switch barrel traditonal style rifle with external  adjusted scope offhand.

While the 32's have always been match winners and no doubt from a bench rest have signifigant advantage smaller calibers are going to shoot higher scores offhand.

Offhand Recoil is more important than very small differences in wind drift.  if .25's have about 1 moa more drift than 32's that is not going to cost many points on a light wind day. Stronger wind it may be more difference.   

However the 28's or 7 mm bullets have about the same ballistic performance as 32 caliber bullets with sigifigantly less recoil.  That means you can either shoot a lighter rifle with the same recoil as a 32 or the same weight with less recoil..   

If a person was truly concerned with shooting the highest possable score in offhand matches I would suggest a modern striker action with internal adjustable scope in a short case 7 mm/28 caliber.  If the rifle could switch barrels easaly I would have a 2nd in 25 caliber for light wind days.

Boats

Fred

The 25 scores may be intresting but I don't think enough of them have been shot offhand to show any trend. I could be wrong and if anyone has some notable Hudson scores shot with a 25 caliber I would like to see it too.   

I don't think re-entry target scores are indications of the calibers potential and would only pay attention to either a full 100 shot Hudson or one of ISSA's 50 round matches. 

As far as .22's  Steve Garbe several years ago shot a Hudson match at 200 yards rimfire with very good result.  I understand it was under perfect conditons which no doubt favored the rimfire It hardly recoils at all and there is no loading to worry about letting the shooter focus on shooting.

Still my opinion is match to match under any possable conditon a 28 would be the caliber to shoot if offhand performance  is the objective.  If perfect conditons exisit I think I would bet on the 22 rimfire over the 25 centerfires.  Just less to worry about when shooting.

I have had a mind to order out a 28 from Paul Shuttleworth for some time with a lighter barrel than I currently shoot. Not that I think it will make any difference in scores at my level but who knows.  Besides if 3 barrels are good 4 must be better

Boats