Difference in zeros?

silentweapon · Post by **silentweapon** » Sat Oct 21, 2006 3:14 pm

How much can I expect a subsonic load to drop compared to a supersonic load both fired out of the same gun, 18" barrel Rem 700?

rockpup · Post by **rockpup** » Sat Oct 21, 2006 4:05 pm

Depending on the twist rate of that barrel you might want to send a dozen (or two) rounds down range to make sure they are stable before you wipe the baffel stack out in your can.

EBR recomends a 1:10 twist for their .308 stuff, and I know my 700p is 1:12.

Other then that, no clue.

brianb · Post by **brianb** » Sun Oct 22, 2006 12:29 am

You kinda need to define your zero range to make it useful, unless you want to consider pure drop.

here's what the ballistic calculator shows:

for a 150 yd zero

150gr .30 at 2700 fps
mid-range at 100yds is +1.03"
200yd impact is -1.20"

150gr .30 at 1050 fps
mid-range at 75 yds is +8.84"
200yd impact is -17.40"

for a 100 yd zero

150gr .30 at 2700 fps
mid-range at 75yds is +.15"
200yd impact is -4.99"

150gr .30 at 1050 fps
mid-range at 50 yds is +3.43"
200yd impact is -33.54"

for pure drop:

........ 1050....... 2700 (fps)
0 yds.. .00....... .00 (in drop)
25....... .99....... .15
50...... 4.02..... .62
75...... 9.13.... 1.43
100... 16.39..... 2.61
125... 25.75.... 4.20
150... 37.44.... 6.22
175... 51.45.... 8.71
200... 67.82... 11.71

BC of .27

cyclone72 · Post by **cyclone72** » Sun Oct 22, 2006 6:55 am

rockpup wrote:Depending on the twist rate of that barrel you might want to send a dozen (or two) rounds down range to make sure they are stable before you wipe the baffel stack out in your can.

EBR recomends a 1:10 twist for their .308 stuff, and I know my 700p is 1:12.

Other then that, no clue.

my Savage has 1:10, what is the highest grain I can go,I ahve been told 190,it doesnt matter if I use smaller grain bullets cause theyre easier to stabilze right? I just need to be careful with the heavy bullets?

silentweapon · Post by **silentweapon** » Sun Oct 22, 2006 11:11 am

brianb wrote:You kinda need to define your zero range to make it useful, unless you want to consider pure drop.

here's what the ballistic calculator shows:

for a 150 yd zero
150gr .30 at 2700 fps
mid-range at 100yds is +1.03"
200yd impact is -1.20"

150gr .30 at 1050 fps
mid-range at 75 yds is +8.84"
200yd impact is -17.40"

for a 100 yd zero

150gr .30 at 2700 fps
mid-range at 75yds is +.15"
200yd impact is -4.99"

150gr .30 at 1050 fps
mid-range at 50 yds is +3.43"
200yd impact is -33.54"
for pure drop:

........ 1050....... 2700 (fps)
0 yds.. .00....... .00 (in drop)
25....... .99....... .15
50...... 4.02..... .62
75...... 9.13.... 1.43
100... 16.39..... 2.61
125... 25.75.... 4.20
150... 37.44.... 6.22
175... 51.45.... 8.71
200... 67.82... 11.71

BC of .27

It is a 190 gr bullet I haven't checked it yet but lets assume 1050, the super sonic bullet is a 168 flying at 2450fps.
The super sonic is hitting dead on at 100 yards so by looking at your chart and assuming a 168 grain bullet is going to have more drop than the said 150, and the 190 is definitly going to have more drop then there sould roughly be somewhere around a 15-18" drop difference between the 2 right?

Artful · Post by **Artful** » Sun Oct 22, 2006 11:36 am

cyclone72 wrote: my Savage has 1:10, what is the highest grain I can go,I ahve been told 190,it doesnt matter if I use smaller grain bullets cause theyre easier to stabilze right? I just need to be careful with the heavy bullets?

It's not the weight it's the length of the bullet - the longer it is the more spin at slower speeds it needs to remain stable in flight. your 190 grain bullet as a flat base round nose will be able to use a slower twist than that same bullet as a rebated boat tail spirepoint hollowpoint a much longer bullet with that same weight.

check this link
http://www.silencertests.com/silencer-f ... =greenhill

cyclone72 · Post by **cyclone72** » Sun Oct 22, 2006 11:40 am

thanks.

NukeMech · Post by **NukeMech** » Thu Nov 23, 2006 9:49 pm

silentweapon wrote:
brianb wrote:You kinda need to define your zero range to make it useful, unless you want to consider pure drop.

here's what the ballistic calculator shows:

for a 150 yd zero
150gr .30 at 2700 fps
mid-range at 100yds is +1.03"
200yd impact is -1.20"

150gr .30 at 1050 fps
mid-range at 75 yds is +8.84"
200yd impact is -17.40"

for a 100 yd zero

150gr .30 at 2700 fps
mid-range at 75yds is +.15"
200yd impact is -4.99"

150gr .30 at 1050 fps
mid-range at 50 yds is +3.43"
200yd impact is -33.54"
for pure drop:

........ 1050....... 2700 (fps)
0 yds.. .00....... .00 (in drop)
25....... .99....... .15
50...... 4.02..... .62
75...... 9.13.... 1.43
100... 16.39..... 2.61
125... 25.75.... 4.20
150... 37.44.... 6.22
175... 51.45.... 8.71
200... 67.82... 11.71

BC of .27
It is a 190 gr bullet I haven't checked it yet but lets assume 1050, the super sonic bullet is a 168 flying at 2450fps.
The super sonic is hitting dead on at 100 yards so by looking at your chart and assuming a 168 grain bullet is going to have more drop than the said 150, and the 190 is definitly going to have more drop then there sould roughly be somewhere around a 15-18" drop difference between the 2 right?

Gravity works the same on both bullets. Differences you find will be due to drag and accelleration. Higher drag bullets will slow down faster which gives gravity more time to act on it at a given distatance with the same muzzle velocity. Clear as mud?