GRT help

[Adam in WI]

Gordon's reloading tool: .25-06, 115 NBT, Ramshot Magnum. Twice measured case capacity at 69.1 grains. The simulation tells me I should be in the 3270 ballpark. I measured 3084 average via Magnetospeed. Running the OBT automatic calibration it tells me that calibration is not possible for the given velocity. My bullets are Moly coated and I do not know how to account for that. If I drop my start pressure to the standard primer value the simulation will give me node values. Any ideas?

 

[Beiruty]

What is barrel length?
COAL?
Jump to the land?

 

[Adam in WI]

26"
3.225"
~.020"

 

[jelenko]

Any scenario that gets to 3270 fps in GRT shows serious overpressure.

What powder charge are you using? What barrel length? What projectile length [did you use the one from GRT?], what overall cartridge length did you use?

Using the defaults in GRT, I get 3199 fps at 61.1K psi with 61 grains of Ramshot Magnum.

 

[jelenko]

26"
3.225"
~.020"

Why 3.225? GRT default is 3.25

However, with the default of 3.25 COAL and 26" barrel, GRT shows 3267 fps.

But, I can run OBT with an average speed of 3084.

 

[Adam in WI]

Why 3.225? GRT default is 3.25

3.250 puts me right at the lands

 

[Beiruty]

What is the bullet used?
Those are the bullets available in GRT.
If it is a custom bullet, we need exact bullet dimensions.
Also, have you played with bullet resistance?

 

[Adam in WI]

115 Nosler BT

 

[Beiruty]

What powder charge got you 3084 fps?
Was it 61gr?

 

[Adam in WI]

61.0

 

[Beiruty]

To get you a 3086 fps with the exact measurements provided at 70F and 61gr RAM Magnum,
The bullet should have an extra 5450 PSI of resistance and Primer "output" of just 1000 PSI (Very weak)