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Discussion Starter #1
We have been making graphs of the velocity curves for the .30-30AI cartridge we are playing with.
Norm Johnson had advised us to watch for flat spots in velocity as we increased our powder charges while working up loads. We have noticed that with extruded powders the graphs show a straight line increase that is very predictable from starting loads up to our cut off point, which is based on pressure ring expansion.
Ball powders on the other hand have shown an interesting difference. Up to 85% case capacity the velocity increase has been predictable and has averaged double digits with each increase in charge weight. After 85% case capacity has been reached ball powder has shown a decrease in velocity gains with an increase in pressure. As the loads went above 95% case capacity the velocity increase dropped to single digits while the pressure continued to rise. The velocity curves show that the velocity gains flattened out as 100% case capcity was approached.
Within our self imposed pressure ring expansion limits both ball and extruded powders provided our goal velocities with each bullet weight. Hodgdon 4895 and Hodgdon 335 have proved to be interchangable grain for grain just as several of the contributors on this board said they would be.
The Hodgdon Extreme powders and Alliant Reloader 15 have proven to be very tolerant of temperature changes.
Has anyone else experianced flat spots in velocity gains with loads that are short of "maximum" while working up loads?
 

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The Hog Whisperer (Administrator)
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Very interesting, have you been able to draw any comparisons between single-base extruded powders and double-base extruded powders (say Benchmark or Varget either of which would seem possibly useful for this application)?

I'm wondering if it's the ball powder geometery (hence the deterrents coatings) or the nitroglycerin content that is making this happen, or perhaps some other factor.
 

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Discussion Starter #3
MikeG
I am not sure if what we are seeing will stand the test of time.
We have looked closely at Varget. It and Hodgdon 4895 are leaders in this cartridge.
Ladder loads using Varget and the Hornady 165 grain A-Max produced an even climb in both indicated pressure and velocity. From 38.0 grains to 40.0 grains Varget gained 62 fps per grain of powder. These are ten shot averages for each load. Be advised these are not recommended loads. The 40.0 grain load is over our pressure ring stop point in the Winchester and 39.0 grains is over our stop point in the Marlin. 40.0 grains of Varget with the 165 grain A-Max gave the first (and only) sign of sticky extraction (in the Marlin) we have seen with the .30-30AI. Ackley says in the chapter on pressure in his Handbook for Shooters and Reloaders that if you experiance sticky extraction with an Improved case you are well beyond where you should be .
Using Varget and the Sierra 170 grain flat base/flat nose bullet, Varget gained 61 fps per grain of powder. Again just as steady as could be. This repeated in both rifles.There is something special about Varget.
My wife has pointed out that the standard deviation for the ball powder loads (H-335, H-BLc2 and Winchester 748) are not as low as those recieved from H-4895 and Varget. There can be many reasons for that such as our primers not being the best for the powder etc. Even neck tension can affect velocity and SD.
To be honest plotting graphs on the computer is not proving to be easy for me. Because the ball powders met our velocity goals within our measured pressure restrictions I am not certain that we are learning anything! Our it could be that this raging cold has muddied my thinking!
 
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