@Grifm
I've been thinking about your earlier post. A lot of us have been working with the new AH bullet. As BBean stated in his reply, what we have learned is that the AHs are an entirely different animal when developing loads. Traditional rules and expectations do not entirely apply in the way we have always thought.
There are a couple of misconceptions in your earlier post. "The same principles apply to AHs that apply to all other bullets." This is not entirely true.
First, the design of the AH is such that engraving pressure does not change with powder charge. The ogive of the bullet never touches the rifling. Only the PDR drive bands touch the rifling – and this is a significantly lesser engraving pressure – always. It is also constant. The bullets are so easy to move, they can move "prematurely" before full ignition is achieved; before the case mouth seals and speed is reached. For this reason, Steve recommends magnum primers to help give the bullet a little "start" on it's trip toward full speed. Also, most have learned that increased neck tension helps in this process of retarding bullet movement until more pressure is generated. Increased neck tension may mean using 3-4 thousandths neck tension rather than a more customary .002 neck tension. Others (most notably BBean) have experimented very successfully with additional neck tension after bullet-seating using the Lee Factory Crimp Die. BBean has achieved some eye raising speeds in his rifles, as have others using factory crimp dies or jamming the
drive bands into the rifling just a little to delay initial bullet movement (25WSM).
In my testing, I found that increasing neck tension up to .004 shows measurable results in some cartridges. Beyond .004 I could see no improvement. My thinking is that once you seat the bullet, you stretch the neck out to bullet diameter and the case can only exert so much pressure at that point. Neck crimping can add additional tension after seating the bullet.
Your basic logic is sound with traditional bullets. AHs behave differently. Because of the low friction with the AHs, you are correct in that traditional powders may not achieve the full velocity potential of the bullet. That is why most use significantly faster powders, with increased neck tension, to achieve the best velocity possible within pressure constraints.
If you cannot achieve desired velocity, go to a faster powder. After you try several powders, you will bracket the pressure/velocity envelope that you need. If you max out in case space before velocity, drop down to a faster powder. Keep doing this until you arrive at a decent case fill amount, and achieve the fastest velocity you can without pressure. I went through 4 different powders and 3 primers developing one load. Others have had the same experience. This is all "new ground" with these bullets. It was Steve's idea (Hammer Bullets) to try and capture this new knowledge. That is the reason for the data spread sheet in this thread. Sharing information saves a lot of confusion and mis-steps for others like yourself.
In your example of the Creedmoor, you are correct in one aspect. You
can go up in powder charge with R-17 to see if you can gain more velocity before hitting pressure. My bet would be go to a much faster powder because you can run a lot more of it before hitting pressure with the reduced friction of the AHs.
In fact, if you look at the load data spreadsheet (post #2), you will find that the most successful Creedmoor loads used powders Waay faster that R-17.
