QuietTexan
Well-Known Member
Is that just a magic point where the very slight boost from the tail wind counteracts spin drift perfectly? I do love random stuff like that though 
Hammer ballistic coefficient tests...
- Thread starter entoptics
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It would be great to hear from @mcdil, @RockyMtnMT, @nralifer on this thread.
And my 7 Allen
(zeroed at 200y)Attachments
Longrangers
Well-Known Member
YeahIt would be great to hear from @mcdil, @RockyMtnMT, @nralifer on this thread.
And my 7 Allen
I'm zeroed at 100.
Altitude that I confirmed it was at 1100 at a 1000 yd range.
mcdil
Well-Known Member
@Northkill less than 14 MOA elevation correction with a 200 yard zero at 1000 yards...................... 
I've seen this post, and I really don't think it's about Hammers at all, rather more about a method of calculating BC, but I've stayed away just because of the title and some of the dialog as well. Good points on all sides, no doubt. Just didn't want you to think I was ignoring you, lol.
As far as the method, it's exactly what we do internally for our BC numbers, so no argument here. It's definitely not about taking those values directly into the hunting field, and we mention that specifically in our literature on purpose, it's about coming up with a repeatable and economical way as a bullet manufacturer, sans all the variation associated with optics adjustments, shooting errors, etc, to provide a BC value our customers and potential customers can start with, and they have full disclosure in how we came up with those values. It's really the best we can do.
I've seen this post, and I really don't think it's about Hammers at all, rather more about a method of calculating BC, but I've stayed away just because of the title and some of the dialog as well. Good points on all sides, no doubt. Just didn't want you to think I was ignoring you, lol.
As far as the method, it's exactly what we do internally for our BC numbers, so no argument here. It's definitely not about taking those values directly into the hunting field, and we mention that specifically in our literature on purpose, it's about coming up with a repeatable and economical way as a bullet manufacturer, sans all the variation associated with optics adjustments, shooting errors, etc, to provide a BC value our customers and potential customers can start with, and they have full disclosure in how we came up with those values. It's really the best we can do.
Longrangers
Well-Known Member
How much energy at 1000yds?It would be great to hear from @mcdil, @RockyMtnMT, @nralifer on this thread.
And my 7 Allen
I think my accuracy load for the 195 EOL in the 7 Allen was at 3,300 fps in a 24" barrel which was a bit below pressure. Yours is smokin for a 28N...
1605 lb which is less than the 195's for sure. But with mono's it's more about velocity and it's still running nigh 2,200 fps at 1K... (calculated/shot drops at 500' elevation)
The 195's are running really close in velocity at 1k though, but I'd wager the BD-2's will still penetrate further.
cohunt
Well-Known Member
So-- aren't we all just compromising and settling on a "random" BC number that gets us closest to actual drops in the field?
If you are actually shooting at LONG distances (hammer bullets are not really designed for that but let's assume they are being used this way)---- a bullets actual BC number is an always changing number that will slowly decrease over distance/time as the velocity of the bullet decreases --
This is a known and proven fact that bc numbers change with speeds, I know that hornady actually posts more than one bc number based on bullet speed.
So if you really want to figure out a true bc-- it is a never ending changing calculation over time due to velocity and many factors.
That would be pretty time consuming for any company to calculate and post all the numerous combinations of bc's for a particular bullet with altitude/weather changes, velocity changes, twist rate changes, etc
So a manufacture at some point has got to just pick an "average" number that works for most people in the intended situations.
I fully understand the frustrations with inflated bc numbers --- I remember when nosler came out with the long range accubond with highly inflated bc numbers-- I think hornady has done the same in a few cases iirc.
So the best thing we can all do is check actual drops in the field with hard data entered into a calculation app so we know what the bullet is going to do in our specific situation. Even then, wind is still an ever changing factor once we pull the trigger.
There is no one- concrete number that can be used for every situation.
For hitting steel I'm not opposed to just punching numbers into an app and sending one on its way-- but for hunting, you need to check your drops in the field and either make a dope card or true your bc/velocity numbers in your apps based off actual in field data.
Iirc, the labradar uses a calculated muzzle velocity so it would be best to not use the "0 yard mark" as a data point-- the magnetospeed can't get down range data but uses a measured not calculated mv -- so a combo of the two might help also.
If you are actually shooting at LONG distances (hammer bullets are not really designed for that but let's assume they are being used this way)---- a bullets actual BC number is an always changing number that will slowly decrease over distance/time as the velocity of the bullet decreases --
This is a known and proven fact that bc numbers change with speeds, I know that hornady actually posts more than one bc number based on bullet speed.
So if you really want to figure out a true bc-- it is a never ending changing calculation over time due to velocity and many factors.
That would be pretty time consuming for any company to calculate and post all the numerous combinations of bc's for a particular bullet with altitude/weather changes, velocity changes, twist rate changes, etc
So a manufacture at some point has got to just pick an "average" number that works for most people in the intended situations.
I fully understand the frustrations with inflated bc numbers --- I remember when nosler came out with the long range accubond with highly inflated bc numbers-- I think hornady has done the same in a few cases iirc.
So the best thing we can all do is check actual drops in the field with hard data entered into a calculation app so we know what the bullet is going to do in our specific situation. Even then, wind is still an ever changing factor once we pull the trigger.
There is no one- concrete number that can be used for every situation.
For hitting steel I'm not opposed to just punching numbers into an app and sending one on its way-- but for hunting, you need to check your drops in the field and either make a dope card or true your bc/velocity numbers in your apps based off actual in field data.
Iirc, the labradar uses a calculated muzzle velocity so it would be best to not use the "0 yard mark" as a data point-- the magnetospeed can't get down range data but uses a measured not calculated mv -- so a combo of the two might help also.
That is indeed correct if you're using a G1 model BC. That is why I've focused my discussion points in this thread on the G7 model which is way more constant than a G1 for the exact issues you're talking about. A G7 BC is what we should be focused on more so that we don't really have to worry about how much it changes during the flight of the bullet.
And yes, many manufacturers like Hornady and Sierra have historically posted multiple G1 BC figures along with the velocity range for each figure.
See here for more:
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mcdil
Well-Known Member
Totally agree. We delete this value prior to creating our fit curve.
I have an Oehler 89 which precisely measures BC from velocity and time of flight. The Oehler measures the BC in your particular gun. I've seen them produce different BCs in different guns.
I've measured a few bullets so far and I tested Tubbs' nose ring and it's affect on BC.
I've attached a couple reports for the 250 a-tip, 225 eld-m, 112 barnes matchburner and the 153.5 Berger in a creedmoor.
The only three methods of finding BC that really hold water out to distance are AB Doppler, Oehler systems and truing via measured drops. The problem is finding the AB RV near you and the price of the Oehler.
I will be testing the 124 HH before I head out elk hunting in November.
I've measured a few bullets so far and I tested Tubbs' nose ring and it's affect on BC.
I've attached a couple reports for the 250 a-tip, 225 eld-m, 112 barnes matchburner and the 153.5 Berger in a creedmoor.
The only three methods of finding BC that really hold water out to distance are AB Doppler, Oehler systems and truing via measured drops. The problem is finding the AB RV near you and the price of the Oehler.
I will be testing the 124 HH before I head out elk hunting in November.
Longrangers
Well-Known Member
This what mine is at a grand.
Attachments
Yeah, good stuff. I should play around more with the 195...
There's BIG misses on assigned BC numbers, and there's small misses, versus true G7 BC. The big misses are the problematic ones. The clusters. They can be prevented with today's equipment... even with a $700 LabRadar.
When I collect LabRadar bullet velocity in 20yd increments out to 80 and 100yds, I receive velocity recordings that allow the determination of velocity loss for each 20 yards of bullet travel down range. I receive this data for each bullet fired. The LabRadar isn't 100% accurate on each bullet fired. Discrepancies can be identified with a basic review of the data, and a comparison of data, from each bullet fired. The velocity loss per 20yds of bullet flight for any given bullet is most often in agreement, within 2fps, and quite often within 1fps.
After reviewing the data from each bullet, confirming the data is in good agreement with the the other bullets fired, I determine the "average" velocity loss/20yds for the group of bullets fired. If I add that value to the "average" 20yd velocity, I get my "average" muzzle velocity, which is then used to reverse calculate that bullet's G7 BC value.
Having explained that, after having gone thru my process dozens of times, I can state that the LabRadar's calculated MV is so close to the MV I get thru my analysis of that data, that I really don't ever change the LabRadar calculated MVs by more than 1fps. Unless the LabRadar has obviously puked out faulty velocity data. In that case, I can discard the velocity for that bullet. Not include it when calculating "avarage" velocities for that group of bullets. And anyone that's been through this process understands that a 1fps error in MV is completely insignificant in the accurate determination of any velocity-based BC value.
