diferent point's of impact

[dodd3]

i did some testing with the buff classic using the lee 500r cast bullet and gas check fitted  and a custom cast 350 grn with gascheck. the 500r load was dooing 1679fps through the crono and the 350 grn custom was dooing  1995 fps through the crono. set up target a 25 meters shot 3 of the 350 grn then 3 of the 512 grn 500r the 350 grn where hitting 1/2" higher than the 512 grn moved target to 50 meters and shot again point of impact the same with both bullet's. moved target to 100 meters and the 512 grn bullet was hitting 1-1/4" higher than the 350 grn bullet,moved target out to 200 meters the 512grn where hitting 1-3/4" higher than the 350grn bullet.all the test shot's done with the sight set the same for both bullet's.i think it is because the lee 500r bullet  has a bc of .443 as to the bc of the 350 grn of around 215. which leeds to a flatter Trajectory. that is what i conclude any outher sugestions.
bernie  

[pascalp]

Hi bernie,
Your range experiment make me thinking. I don't feel that BC may be enough to invert effect of speed and weight on trajectory.

Calculation give a "height drop" of 27.84" at 200m for the 350gr and 33.77" for the 512gr, with speed and BC indicated.
The heavier haven't the flatest trajectory.
with re-zeroized sights, your conclusion may be different.

If you have time to verify/reject theory, please post yours results.

_______________________________________________________
Projektil 2  RBTech (c) 1999 R. Becker

Weight of bullet :       350,0 grain
muzzle velocity :    1994,878 feet/sec.
bullet diameter :       0,457''
ballistic coefficient :      0,215
height of sight above bore :   2,54 cm
zeroing distance :      100,0 m
maximum height :      1,18 inch
at :         60,0 m
with an angle of :    0,107
elevation     :       0,0 m
humidity :       78, %
temperature       :       59,0 F

Range_m   V_fps   height/sightline_"   horizontal_drop_"
0   1994,88   -1   0
10   1955,58   -0,35   0,05
20   1917,03   0,19   0,21
30   1879,18   0,63   0,48
40   1841,99   0,94   0,86
50   1805,44   1,12   1,38
60   1769,48   1,18   2,02
70   1734,1   1,1   2,8
80   1699,26   0,88   3,72
90   1664,94   0,51   4,79
100   1631,11   0   6
110   1597,77   -0,66   7,37
120   1564,88   -1,48   8,88
130   1532,43   -2,46   10,56
140   1500,4   -3,59   12,39
150   1469,89   -4,96   14,46
160   1439,72   -6,5   16,7
170   1410,6   -8,25   19,15
180   1382,42   -10,22   21,83
190   1355,09   -12,42   24,72
200   1328,55   -14,84   27,84

_______________________________________________________
Projektil 2  RBTech (c) 1999 R. Becker

Weight of bullet :       512,0 grain
muzzle velocity :    1678,898 feet/sec.
bullet diameter :       0,457''
ballistic coefficient :      0,443
height of sight above bore :   2,54 cm
zeroing distance :      100,0 m
maximum height :      1,53 inch
at :         60,0 m
with an angle of :    0,000
elevation     :       0,0 m
humidity :       78, %
temperature       :       59,0 F

Range_m   V_fps   height/sightline_"   horizontal_drop_"
0   1678,9   -1   0
10   1662,32   -0,19   0,08
20   1645,87   0,46   0,3
30   1629,52   0,97   0,68
40   1613,29   1,31   1,22
50   1597,17   1,5   1,92
60   1581,16   1,53   2,77
70   1565,25   1,39   3,79
80   1549,45   1,09   4,97
90   1533,74   0,63   6,32
100   1518,14   0   7,84
110   1502,63   -0,8   9,52
120   1488,07   -1,87   11,47
130   1472,95   -3,05   13,53
140   1458,12   -4,43   15,79
150   1443,55   -6,01   18,26
160   1429,22   -7,8   20,93
170   1415,14   -9,8   23,82
180   1401,28   -12,01   26,92
190   1387,63   -14,44   30,23
200   1374,19   -17,09   33,77

[trotterlg]

Slower bullets hit higher on the target because the muzzel has more time to recoil up before the bullet leaves the barrel, it even works that way on my 4,200 fps 17 Remington.  Larry

[Busta]

Slower bullets hit higher on the target because the muzzel has more time to recoil up before the bullet leaves the barrel, it even works that way on my 4,200 fps 17 Remington.  Larry

Bernie,

I think Larry has it covered here. I experience the same thing in my .50 caliber muzzleloaders with light and heavy conicals. The only thing that has me scratching my head is that you said the lighter bullets hit higher at 25 yards???  :?  I believe it to be in direct relation to the time spent in the barrel and recoil, thus the heavier bullet leaves the barrel with a higher initial angle of trajectory and it does have a higher BC due to it being longer.

[dodd3]

guy's what larry said about recoil, got me thinking where we did the test at 25 meters of the bench we were shooting at a slight angle down at the target and as i recall the recoil was felt more from the 512 bullet than any of the outher rainges.it mite be that becase of the angle the gun came straight back,the 50 meters was at a slight angle up as were all the rest.i might and that wee did this test two times, i shot first then my budy the second time with just abought the same result we where shooting of a rest like quickdetoo has so the buff was held nice and steady all the time.
bernie