Mysticplayer
Well-Known Member
- Joined
- Jul 27, 2001
- Messages
- 1,459
meichele, I have had bizarre results with the 140gr SST in 6.5 and the 162gr Amax in 7mm. Both shoot way flatter then they are supposed to. Both are also launched close to or over 3000fps.
My 7RM at 3150fps needs about 17.5min to get to 940yds. My Kreriger match rifle needs 1.5min more at every distance which agrees with its slower muzzle velocity when data is crunched.
When plugging in the numbers in the JBM software, I use the pub BC, velocity but change the G function. I got a match almost to the click out to 940yds using a G7 function.
Well, a BC of 0.625 with a G7 drag function is pretty slippery. I wonder if after they slow down below 2400fps they start to really decelerate? Will have to shoot beyond 1000m to find out.
For comparison, the 150gr SST 270 bullet flies with only a G5 function. Pretty sluggy. The 155gr 30cal Amax flies really well too and stays stable after going subsonic.
So as I mentioned before, comparing BC does not mean much until you know which drag function is being used. In general, the Poly tipped bullets have flown flatter then the equivalent weight/cal HP in several of my rifles.
For those that keep saying can't be so, just buy a box, launch them in your rifle and see what happens. I doubt its the water above the 49th parallel.
Maybe it's the beer...
Jerry
PS meichele, send me your address and I will forward you some 220gr MK in the name of science.
My 7RM at 3150fps needs about 17.5min to get to 940yds. My Kreriger match rifle needs 1.5min more at every distance which agrees with its slower muzzle velocity when data is crunched.
When plugging in the numbers in the JBM software, I use the pub BC, velocity but change the G function. I got a match almost to the click out to 940yds using a G7 function.
Well, a BC of 0.625 with a G7 drag function is pretty slippery. I wonder if after they slow down below 2400fps they start to really decelerate? Will have to shoot beyond 1000m to find out.
For comparison, the 150gr SST 270 bullet flies with only a G5 function. Pretty sluggy. The 155gr 30cal Amax flies really well too and stays stable after going subsonic.
So as I mentioned before, comparing BC does not mean much until you know which drag function is being used. In general, the Poly tipped bullets have flown flatter then the equivalent weight/cal HP in several of my rifles.
For those that keep saying can't be so, just buy a box, launch them in your rifle and see what happens. I doubt its the water above the 49th parallel.
Maybe it's the beer...
Jerry
PS meichele, send me your address and I will forward you some 220gr MK in the name of science.
