I'm hoping someone can help me understand something I came across in Nosler's loading manuals. I was comparing load data between Nosler's #5 and #6 manuals and found some large differences. When I first looked at the .308 Win data I noticed a large number of compressed charges. Upon further inspection the loads were reduced in the new manual (I specifically was comparing 180gr loads). Checking the details of the load I took note Nosler was now using their brand of brass for the case in lieu of the Winchester brass used in the previous manual. So, I figured the case walls were thicker thus reducing the useful capacity of the case.
Subsequently, I compared the 45 ACP data and noted while the charges were the same, the load densities were very different for every powder; some by as much as 31% (GreenDot). With the exception of one powder, AA #5, the load densities were all at least 14% more for a maximum charge.
To further confuse matters, it appears as though all of the muzzle velocities for the data I was looking at were identical in both of the manuals.
If the load densities are being obtained as described on Page 70 of the new manual, and Nosler has been consistent with their method, how can it change for every powder? If you follow the method, it would suggest all powder is becoming more volumetric for a given weight; less dense.
So, the question is 1.) is this just how much powder can vary from lot to lot? 2.) Is powder actually becoming less dense, 3.) Does Nosler brass have relatively thick case walls? And, 4.) Am I trying to read too much into different sets of data, and possibly just need to take the data at face value and be happy?
Subsequently, I compared the 45 ACP data and noted while the charges were the same, the load densities were very different for every powder; some by as much as 31% (GreenDot). With the exception of one powder, AA #5, the load densities were all at least 14% more for a maximum charge.
To further confuse matters, it appears as though all of the muzzle velocities for the data I was looking at were identical in both of the manuals.
If the load densities are being obtained as described on Page 70 of the new manual, and Nosler has been consistent with their method, how can it change for every powder? If you follow the method, it would suggest all powder is becoming more volumetric for a given weight; less dense.
So, the question is 1.) is this just how much powder can vary from lot to lot? 2.) Is powder actually becoming less dense, 3.) Does Nosler brass have relatively thick case walls? And, 4.) Am I trying to read too much into different sets of data, and possibly just need to take the data at face value and be happy?
