B
benconrad
Guest
For the 6ppc I read about load windows. What is this and what are the settings for n133 and 8208.
ie what grains and or what velocity??
ie what grains and or what velocity??
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B
BJS6
Guest
It seems generally accepted that a custom 6mm PPC will shoot well at a variety of different load weights and thus velocity levels. It seems that these load windows and they are often called fall around 100 - 120fps apart and around 1.2 grains N133 apart.
In my benchrest rifle it will shoot well at around 28.6-28.8 grains and again at around 29.8-30.0 grains N133 with a Barts Ultra 68 grain bullet. Another rifle I had in 6PPC shot well down around 27.5 grains which pretty much slots into the low window.
So say my rifle would shoot at 27.4, 28.6 and 29.8 grain N133, or low, middle and upper window loads. This respresents three velocity levels where the bullet exit timing from the barrel favourably matches the barrels vibration pattern. To go half way between these loads you will be as out of tune as is possible and the groups will spread vertically. In my situation the upper window seems to stay in tune over varying ambient conditions better so I use that load.
The specific powder weight at each window will depend on the individual rifle and components but the basic rule seems to apply to a typical benchrest rifle in 6PPC. The actions of these rifles and the brass used are strong enough that the high pressure at the upper loads isn't normally a problem.
Bryce
In my benchrest rifle it will shoot well at around 28.6-28.8 grains and again at around 29.8-30.0 grains N133 with a Barts Ultra 68 grain bullet. Another rifle I had in 6PPC shot well down around 27.5 grains which pretty much slots into the low window.
So say my rifle would shoot at 27.4, 28.6 and 29.8 grain N133, or low, middle and upper window loads. This respresents three velocity levels where the bullet exit timing from the barrel favourably matches the barrels vibration pattern. To go half way between these loads you will be as out of tune as is possible and the groups will spread vertically. In my situation the upper window seems to stay in tune over varying ambient conditions better so I use that load.
The specific powder weight at each window will depend on the individual rifle and components but the basic rule seems to apply to a typical benchrest rifle in 6PPC. The actions of these rifles and the brass used are strong enough that the high pressure at the upper loads isn't normally a problem.
Bryce
W
Wildcatter
Guest
does it appear the load windows for a given gun and powder (velocity) seem to be about the same for other powders? does a gun seem to respond best to the same velocity in another powder or is there no elationship?
TIA
TIA