Do you need a 900 yard Load?

[Aviator]

Your Kestrel will give you station pressure (uncorrected pressure ) IF you set the reference altitude to 0 feet.

Most weather stations will give you pressure corrected to sea level. That is almost certainly what you got from the CRC weather station.

With a calculator like JBM, you can use either, but your entries need to be consistent.

If you are using station pressure (uncorrected), you need to leave the box "Pressure is Corrected" NOT checked, and there is no need to enter any altitude.

If you are using pressure corrected to sea level, then you would need to the check the "Pressure is Corrected" box, and you need to know and enter the elevation. The ballistics calculator will then calculate station pressure itself, from the corrected pressure and the entered elevation.

Either method will give the same result in the ballistic calculator.

Probably the easiest method to use at a range is to set the Kestrel reference altitude to 0 feet, and leave it there. The Kestrel can then give you station pressure, and you do not need to know the elevation of the range.

[Kenny Wasserburger]

Your Kestrel will give you station pressure (uncorrected pressure ) IF you set the reference altitude to 0 feet.

Most weather stations will give you pressure corrected to sea level. That is almost certainly what you got from the CRC weather station.

With a calculator like JBM, you can use either, but your entries need to be consistent.

If you are using station pressure (uncorrected), you need to leave the box "Pressure is Corrected" NOT checked, and there is no need to enter any altitude.

If you are using pressure corrected to sea level, then you would need to the check the "Pressure is Corrected" box, and you need to know and enter the elevation. The ballistics calculator will then calculate station pressure itself, from the corrected pressure and the entered elevation.

Either method will give the same result in the ballistic calculator.

Probably the easiest method to use at a range is to set the Kestrel reference altitude to 0 feet, and leave it there. The Kestrel can then give you station pressure, and you do not need to know the elevation of the range.

That was what I was checking the box using pressure corrected, and entering the altitude. Thank you my friend.

Kenny Wasserburger

[Minerat]

Kenny I think you Relatively humid for Byers is a little high. Last year at Byers is was between 45 and 58% not sure how much this makes a difference.

Also our altitude Barometric pressures is lower then sea level by about 6" for example right now the measured is 24.06inHg but sea level equivalent is 30.11inHg.

The weather station at the club say a Barometric pressure of 30.9 which is what I went by.

Using 24.06 BP the numbers are pretty whacked. And do not make sense for velocities. Amazing how much that changed the numbers for down range velocities. From 884.7 FPS to 942 fps. Which isn’t realistic at 1000 yards. Meaning the bullet never went subsonic.

Kenny

Kenny,

The station at CRC is like mine at home that shows corrected to sea level. I was just wondering if uncorrected made any difference since that is actual pressure at this elevation. Could it be that the ballistic calculator takes that into account when you supply the elevation and pressure?

I agree with the rain that day, the Humidity was high and that wind on Saturday was something else. If you got a RH that high that day on the range then I agree it was the right number to use not what I found.

Interesting that the velocity was that much different when calculated using the pressure lower number. But if that were happening then wouldn't your come ups have been really off from what you have seen from your 1000 yd sight adjustments at different ranges? I realize that a lot of factors cause differences but there should be some correlations that can be used as comparisons.

Remember, This is a WAG for me because I have little on the ground experience in any of this long range work.

[Kenny Wasserburger]

Kenny I think you Relatively humid for Byers is a little high. Last year at Byers is was between 45 and 58% not sure how much this makes a difference.

Also our altitude Barometric pressures is lower then sea level by about 6" for example right now the measured is 24.06inHg but sea level equivalent is 30.11inHg.

The weather station at the club say a Barometric pressure of 30.9 which is what I went by.

Using 24.06 BP the numbers are pretty whacked. And do not make sense for velocities. Amazing how much that changed the numbers for down range velocities. From 884.7 FPS to 942 fps. Which isn’t realistic at 1000 yards. Meaning the bullet never went subsonic.

Kenny

Kenny,

The station at CRC is like mine at home that shows corrected to sea level. I was just wondering if uncorrected made any difference since that is actual pressure at this elevation. Could it be that the ballistic calculator takes that into account when you supply the elevation and pressure?

I agree with the rain that day, the Humidity was high and that wind on Saturday was something else. If you got a RH that high that day on the range then I agree it was the right number to use not what I found.

Interesting that the velocity was that much different when calculated using the pressure lower number. But if that were happening then wouldn't your come ups have been really off from what you have seen from your 1000 yd sight adjustments at different ranges? I realize that a lot of factors cause differences but there should be some correlations that can be used as comparisons.

Remember, This is a WAG for me because I have little on the ground experience in any of this long range work.

Yes the come ups were all wrong, what I ment by whacked numbers. Way faster and way flatter than what I used at the ranch and Byers. This stuff is fascinating.

Kenny W.

[Kenny Wasserburger]

So after all this number crunching, the question, the real question is……or remains. Where does the Phase Inception Point begin? Is it at .8 Mach or is at around 900 FPS? My instinct or gut feeling is it’s somewhere between the two points. My reasoning on this is the following, after about 928 fps the rate of decay in forward velocity drops off significantly. Which fits into the .8 Mach zone quite nicely. At around 900 yards the velocity can be faster or slower than 900 fps but not much. After around 888 fps speed the forward velocity decay again becomes more dramatic in its slow down in forward speed. Is it around 888 fps that our bullets are more susceptible to wind shear. While its rate of decay is much less than the first 300 yards of the bullet’s flight, it is still more than around the point of just at or above .8 Mach.

The math tells us at what specific point of .8 Mach is calculated to occur, based on multiple data inputs, Altitude, Temperature, Humidity, Barometric Pressure, and of course Muzzle velocity and BC of our bullet. Am I missing anything else?

What we aren’t able to input or account for is the variation in down range Topography, or altitude wind and possibly wind shears. These are the real bug a boo in our attempt to understand what’s going on down range at 900 yards.

I have been shooting BPTR at 1000 yards, since the first Creedmoor event in 1996. This summer that will be 29 years. Jimbo and I just discussed this last night, along with another phenomenon we both have witnessed, False Mirage. Around 4-6 times we have seen it and personally dealt with its effects.

A better understanding of the Phase Phenomenon isn’t just for paper punchers or Traditional Creedmoor shooters, it is also good to know for the Mt 1000 yard group.


Kenny Wasserburger

[Don McDowell]

IMHO mirage is a whole nether can of worms. Winds can create as Roger mirage that over shadows a weaker mirage. And quite possibly be the false mirage
And a person needs to be able to get a read on not only ground level mirages but upper level in the midrange trajectory between the muzzle and target at the long lines. Some ranges it’s easy enough to do others with no high points behind the target butts it’s pretty tuff to get a read on that

[desert deuce]

I probably should leave the forum and turn off the computer right now as I am reluctant to allow my fingers to continue dancing across this keyboard. However, I am struggling to dispel that urge. During a very recent conversation I was asked HOW I solved my problem with the 900 yard phenomenon that kept tanking my long range aggregate scores. I answered truthfully, (I know SEMTAV that is difficult to accept), that I did not solve the issue, rather, it solved itself. AND, as a result of that epiphany I want to review something of a succession as to the HOW and what followed.

If you are someone that is reading comprehension challenged, perhaps you should stop right here and go do something else.

As you may or may not know there was a lot of long range shooting available earlier this century, Sacto, Missoula, Lodi, Capitan, Raton, Byers, Phoenix, etc and I was going to and shooting those TARGET matches. Post advent of the Creedmoor Cup matches at Ben Avery with Steve Rhoades and Dan T. and others I started with a rifle new to me for long range. More or less started anew with this new to me rifle and basically the process employed I later outlined in an article I wrote for Black Powder Cartridge News titled, "The Balanced Load."

Briefly, I had been picking the brains of just about any prominent long range shooter that I could get to stand still long enough for me to question them about what they found that worked so well for them. Frank Monikowski, Lige Harris, Rick Moritz, Dave Gullo, Dan T., Mark Schuenke, Cliff Gregg, and lastly, Eron Ahmer. It was shooting with and spotting with Eron that the lights really started coming on.

Additionally, I had a close to home 200 yard range and 800 & 1,000 yard ranges at Tucson so I could pretty much shoot as desired and did employ much of what obviously was working for them. In the end, I found out that what was obviously working for them was not solving my 900 yard dilemma. Paying close attention to Eron's shooting I soon realized he seldom dropped points from vertical distribution. Shot plots showed windage is where Eron was most likely to loose points and some of that fell to spotter inefficiency. It became obvious that controlling vertical distribution on the target was essential. Assuming initial velocity affected down range vertical distribution I dusted off the chronograph and brought it to the 200 yard range to do ladder loads in conjunction with the chronograph.

Finding loads that showed very low extreme spreads on the chronograph frequently indicated reduced vertical distribution at the target. Tightening up ammunition production controls specifically uniform introduction of powder into the case and wad choices reduced vertical even more than indicated on the chronograph and it "SEEMED" switching to 1-16 alloy from 1-20 alloy made some improvements also, at long range.

I am convinced that it was my individual journey with that particular rifle that solved the 900 yard dilemma, AND, the function of the shooter apparently in the equation was one of the more critical factors. In a few words, endeavoring to persevere the 900 yard situation resolved itself. WHY? I really have no logical explanation. It just did it by itself. More or less, but more so than anything else.

[Kenny Wasserburger]

I probably should leave the forum and turn off the computer right now as I am reluctant to allow my fingers to continue dancing across this keyboard.

Additionally, I had a close to home 200 yard range and 800 & 1,000 yard ranges at Tucson so I could pretty much shoot as desired and did employ much of what obviously was working for them. In the end, I found out that what was obviously working for them was not solving my 900 yard dilemma. Paying close attention to Eron's shooting I soon realized he seldom dropped points from vertical distribution. Shot plots showed windage is where Eron was most likely to loose points and some of that fell to spotter inefficiency. It became obvious that controlling vertical distribution on the target was essential. Assuming initial velocity affected down range vertical distribution I dusted off the chronograph and brought it to the 200 yard range to do ladder loads in conjunction with the chronograph.

Finding loads that showed very low extreme spreads on the chronograph frequently indicated reduced vertical distribution at the target. Tightening up ammunition production controls specifically uniform introduction of powder into the case and wad choices reduced vertical even more than indicated on the chronograph and it "SEEMED" switching to 1-16 alloy from 1-20 alloy made some improvements also, at long range.

I am convinced that it was my individual journey with that particular rifle that solved the 900 yard dilemma, AND, the function of the shooter apparently in the equation was one of the more critical factors. In a few words, endeavoring to persevere the 900 yard situation resolved itself. WHY? I really have no logical explanation. It just did it by itself. More or less, but more so than anything else.

Zack, I agree with everything you said, as to the why of things, came together for you. Harder alloy definitely helped with BC, wad Choice better protection to the bullet base, reducing the vertical all are key things I look at also.

I picked up on the tighter ammunition controls, specifically the introduction of the powder to the case, and wad choices reduced the vertical even more. Would you care expound on that a bit?

Kenny Wasserburger.

[Kenny Wasserburger]

Yesterday I ordered a new SD card with all the software updates for my labradar. Since I do not have a personal Computer just a tablet. Total cost was just over $20 including shipping, cheap by any standard. This will update my labradar to current settings.

The jump off date grows closer, ammo is loaded, ready to rock, check list starting. The DI is coming fast.

Kenny Wasserburger

[Kenny Wasserburger]

The Update SD card arrived in the mail today. Not bad for Canadian mail. Our lab radar will be all up dated and ready.

Kenny Wasserburger

[Kenny Wasserburger]

Removed

[Kenny Wasserburger]

This is from a question I put to the AI feature on google. Asking about a bullet going from transonic speeds to Subsonic. Again 900 FPS comes up.


When a bullet transitions from supersonic to subsonic speeds (the transonic region), its flight becomes unstable, potentially causing the bullet to yaw (tip sideways) and leading to larger groups or even wild groups at longer distances.
Here's a more detailed explanation:
Transonic Region:
This is the area where bullets transition from supersonic to subsonic speeds, roughly Mach 0.8 to 1.2 at sea level, which corresponds to muzzle velocities between 900 to 1352 feet per second. 900 fps being the bottom of the Transonic range. Beginning of Subsonic range,
Instability:
The shockwaves created by a bullet are unstable in the transonic region, and this instability can cause the bullet to yaw or tumble. Not an issue as our bullets are designed from the beginning to remain stable through the transonic range.
Factors Affecting Stability:
Over-stabilization: Can affect accuracy.
Excessive RPM: Can cause the bullet jacket to fail. not a consideration
Center of Pressure: Migrates to the front of the bullet as velocity is lost.
Practical Considerations:
Bullet Design: Bullets that are shorter and have shallow boat-tail angles tend to track better through the transonic range.
Twist Rate: Barrels with a faster twist rate can increase a bullet's gyroscopic stability, helping it overcome the dynamic instability it experiences at transonic speed. Bingo! Plus harder alloys increasing the Bullet BC.
Staying Supersonic: To avoid the transonic region, ensure your bullet stays supersonic throughout its flight path. not possible for our application
Examples:
Large, blunt projectiles like .45-70 or .45-90 can maintain some semblance of stability over very long ranges. Ah! Here we go.
The old long-range, 30-cal Sierra bullets (the venerable 190gr, 200gr, and 220gr MatchKings) with their extra length boat-tail sections have a superb reputation for stable transonic/subsonic flight.
Long-Range Shooting: not Applicable.
If you're shooting at long ranges, it's important to consider the transonic region and choose bullets and loads that are stable through it.

After running a lot of numbers, the Phase Inception Point or PIP, looks to occur or happen at around 888 FPS. This makes the most sense, the moment of where our bullets are the most susceptible to condition sheer.

On the subject of BC increasing as our bullets get further down range.
Again from AI.
BC and Velocity:
Most modern bullets exhibit a lower BC as velocity slows down when compared to the G1 standard. However, some bullet shapes may have less drag than the G1 standard at lower speeds, in which case their BC might increase at lower speeds. Here is where our bullet designs and nose shapes fall into that category, the drag is considerably less down range than initially at the first 800 yards. Calculated velocities for our bullets, show considerably less loss in speed per 100 yards after 800 or so down range. This would indicate an increase of BC at these reduced velocities.

Kenny Wasserburger

[desert deuce]

The original Ideal 456132 Postel Bullet had/has a beveled base. Why?

[Kenny Wasserburger]

The original Ideal 456132 Postel Bullet had/has a beveled base. Why?

Better question is what does that bullet base look like after firing?

Lots of designs back in the day, how successful it was is the real question?

My original Ideal Postell is flat based actually. I may have to try it in my 45-100.

Kenny Wasserburger

[steveu834]

Would the Hemispherical Flat Base model give a better picture of what the bullet is doing versus the G1 model?
http://www.geoffrey-kolbe.com/HFB-projectile.htm