Episode 2: 6.5 PRC 26" to 18" barrel velocities test by James Eagleman

[Barbourcreek]

Episode 2:
6.5 PRC 26" to 18" barrel velocities test by James Eagleman, for long-range Hunting @ Barbour Creek

 

[ARlife4me]

Were those factory loads? 91fps loss between 22 and 20 was the biggest deficit. Which ever powder was uses can sure drive certain barrel lengths. Big reason to handload for your gun. I'm about 2,500' above sea level and way less humidity. Good info, what's episode 3 going to be?

 

[Darryle]

Were there Christmas decorations in the background

That is some useful information, thank you sir!

 

[ARlife4me]

Were there Christmas decorations in the background

That is some useful information, thank you sir!

Do you want to put up decorations in the south heat and humidity? Well, you're fairly south?

 

[Barbourcreek]

Were those factory loads? 91fps loss between 22 and 20 was the biggest deficit. Which ever powder was uses can sure drive certain barrel lengths. Big reason to handload for your gun. I'm about 2,500' above sea level and way less humidity. Good info, what's episode 3 going to be?

300 prc . Episode 3

 

[Barbourcreek]

Were there Christmas decorations in the background

That is some useful information, thank you sir!

Yes sir
Philippine wife. Christmas tree goes up early.

 

[Barbourcreek]

Were those factory loads? 91fps loss between 22 and 20 was the biggest deficit. Which ever powder was uses can sure drive certain barrel lengths. Big reason to handload for your gun. I'm about 2,500' above sea level and way less humidity. Good info, what's episode 3 going to be?

Yes factory loads

 

[Calvin45]

Yes sir
Philippine wife. Christmas tree goes up early.

Oh man I know a bunch of Filipino people…in my experience they could teach us all a lesson on how to celebrate! .

 

[Hugnot]

I ran the bullet info thru my Miller program:



I was able to duplicate your data using a bullet OAL with no plastic tip with the Miller Sg method. I used a temperature of 99 deg F & atmospheric pressures of 30 inches & 25 inches of mercury (Hg).

Using standard altitude/atmospheric tables like:

Altitude to Pressure Conversion Table

Convert altitude in feet or metres of height to a pressure reading in millibar, pounds per square inch, millimetres of mercury or inches of mercury.

www.sensorsone.com

A pressure of 25 inches of Hg would correspond to an altitude of 3500 - 4000 ft which is real close to Montana's hunting areas. But - looking at my barometer the current atmospheric pressure is 29.7 inches Hg at 3500 ft. I don't use altitude to determine pressure, a local weather report or barometer works.

Did you use the Miller process & allow for bullet tip length in your calculations?

https://arxiv.org/ftp/arxiv/papers/1410/1410.5340.pdf#:~:text=However%2C%20the%20original%20Miller%20twist,density%20of%20copper%20and%20lead.

https://arxiv.org/ftp/arxiv/papers/1410/1410.5737.pdf

The little plastic tip is regarded as weightless in the Miller Sg process. This is done by subtracting the bullet tip length from the bullet OAL with other unmodified calculations. Minor aerodynamic effects happening with the plastic tip apparently are not important.

For my 6.5-06 loaded with the new Staball HD & my soon to arrive 6.5 PRC I will use:


My Sg values duplicate those of JBM plus -minus .01 which is probably caused by rounding errors.

 

[Barbourcreek]

I ran the bullet info thru my Miller program:

View attachment 495320

I was able to duplicate your data using a bullet OAL with no plastic tip with the Miller Sg method. I used a temperature of 99 deg F & atmospheric pressures of 30 inches & 25 inches of mercury (Hg).

Using standard altitude/atmospheric tables like:

Altitude to Pressure Conversion Table

Convert altitude in feet or metres of height to a pressure reading in millibar, pounds per square inch, millimetres of mercury or inches of mercury.

www.sensorsone.com

A pressure of 25 inches of Hg would correspond to an altitude of 3500 - 4000 ft which is real close to Montana's hunting areas. But - looking at my barometer the current atmospheric pressure is 29.7 inches Hg at 3500 ft. I don't use altitude to determine pressure, a local weather report or barometer works.

Did you use the Miller process & allow for bullet tip length in your calculations?

https://arxiv.org/ftp/arxiv/papers/1410/1410.5340.pdf#:~:text=However%2C%20the%20original%20Miller%20twist,density%20of%20copper%20and%20lead.

https://arxiv.org/ftp/arxiv/papers/1410/1410.5737.pdf

The little plastic tip is regarded as weightless in the Miller Sg process. This is done by subtracting the bullet tip length from the bullet OAL with other unmodified calculations. Minor aerodynamic effects happening with the plastic tip apparently are not important.

For my 6.5-06 loaded with the new Staball HD & my soon to arrive 6.5 PRC I will use:
View attachment 495323

My Sg values duplicate those of JBM plus -minus .01 which is probably caused by rounding errors.

No I used AB mobile. Keeping it simple
I use station pressure (not barometric pressure)
Its a general guideline for hunters
All guns have bore tightness and velocity differences as well as ammunition and projectiles
Its a good standard for all to use as a base line
1600 FPS cup and core bullets
Hope you all can use it. Thanks

 

[59FLH]

On the surface is seams the Mag Spd is affected by muzzle blast and the associated ejecta. Please report back when you resolve the error issue.

Nice work.

 

[Barbourcreek]

On the surface is seams the Mag Spd is affected by muzzle blast and the associated ejecta. Please report back when you resolve the error issue.

Nice work.

I believe you are correct
no issue until short barrel high blast

 

[RockyMtnMT]

I think as hand loaders we can use faster powders in the shorter barrels and negate some of the vel loss. It looked to me like when the barrel got to the 22" mark it quit burning all the powder at a much larger rate. Also giving the magspeed a tough time.

 

[Barbourcreek]

I think as hand loaders we can use faster powders in the shorter barrels and negate some of the vel loss. It looked to me like when the barrel got to the 22" mark it quit burning all the powder at a much larger rate. Also giving the magspeed a tough time.

Agreed
But many are not lucky enough to have time or experience for hand loads
I do every thing factory ammo for the non loaders