The 156 gr ULDs in 257 will stabilize in a 1-8 twist at 3000 ft elevation and at 3350 fps. Of course when loaded to 2900 fps they are not stabilized fully.
I do not feel a bullet is adiquately stabilized when it will go from having nose tears on paper at 100 yards at the low range of its velocity to shooting 2" groups at 500 yards at the high range of its velocity range.
For this reason, I paid to have Dan Lilja tool up for a 1-7" three groove tooling for this bullet and even a slightly heavier pill such as a 165 gr ULD in 257.
I have tested the 156 gr over 500 yards and this bullet is running in the low .800 range for B.C.
The bullets Xphunter is referring to for his 1 mile handgun shoot are predicted to top 1.000 b.c., we will see if they will. They will also be requiring a 1-7 twist.
The 169.5 gr ULDs in .277" are shooting extremely well in a 1-8 twist barrel out of my 270 Allen Mag loaded to 3450 fps. This is really probably a bit more then needed but these are big game rifles used in extreme weather conditions, I would rather be safe then sorry. Especially when a customer of mine lines up on a 170 class Canadian Whitetail at 500 yards in 0 degree weather!!!
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.
Yep, HErm, you may want to edit this statement:
"What most people do not realize is that most of the really high BC bullets require extra fast twists that are not normally used. For example the 115gr 6mm needs either a 7 or 7.5 while most barrel mftrs are only making an 8."
Kirby or Richard -- i can test the 169.5/30 cal bullet against my 175SMK loads in competition from 100-1000yds if either are interested -- you know how to get a hold of me [img]/ubbthreads/images/graemlins/wink.gif[/img]
I have used a lot of different Hornady Amax and SST bullets in several cals and in different rifles. In all cases, the BC in the real world is higher then print. This is based on scope adjustments, muzzle velocity inputted into ballistic programs.
I have also done side by side comparisons between poly tipped bullets like Nosler BT, Amax and Nosler J4 (similar to MK). In all cases, using the same muzzle velocity from the same rifle, the HP match bullet needed more elevation change. This was in the 2 to 4 MOA range at 650yds. That's a lot.
I have now been playing the 6.5 140gr SST and it is something special. I know that my scope adjustments indicate a wacky high BC (I posted this a while back and am still waiting for others to give feedback from their tests). The only thing I know is that this bullet is longer then all 142/139gr match bullets I can get my hands on.
If bullet length is a good indicator of BC, these SST's are higher then MK/Lapua's. If the poly tip reduce drag and increase BC, then these SST's have a higher BC. If they are the same length or longer then a larger cal bullet of known BC, the BC should be higher. They shoot in the 1's too.
So if there are some of these Wildcat bullets around, why not just compare them to heavy MK's. We know that the data from Sierra is very close to real world experience.
If say these Wildcats are as long as a 190, 200, or 220gr MK, there is grounds to assume that the BC is similar. Of course, real world testing is still needed but a good start.
I have 200 to 240gr MK so if someone can measure these wildcats and post it, I will compare.
PS if length is a good indicator of BC, the Hornady 308 165gr Interbonds are even longer. Higher BC????
I really have limited experience with calculating B/C's but I did notice the the 75gr A-Max (.224) when fired at close to 3,700 ft/sec ALWAYS printed above what was indicated on my ballistic chart when I plugged the stated B/C into the software.
It was very noticeable out past 500 yds or so. I just figured that the software wasn't that accurate, but who knows? Maybe its the moly. [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/wink.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]
I too have noticed the b.c on the 224 bullets to be lower than it actually is. My guns are right on with .224 a amx with a B.C of .475. Also the sierra and nosler 80 gr .224 rate their b.c at .440 in my guns it seems that it is around .5. Maybe they calcuate the B.C ate different allitudes or something, but most of the time they don't seem to be on, close but not perfect.