Russell,
I am just new to this stuff but have been doing a lot of homework on loads with regards to what shoots in my rifle and what loads typically work in most rifles. I have a lot to learn about wind reading etc but my rifle seems to shoot pretty well.
As best I can tell it seems pretty common for a typical LV 6PPC with a 68 grain bullet to shoot well in the 29.8 - 30.2 grain range of N133. My rifle likes 29.8 grains with a 68 Ultra and 30.2 with a 66 Ultra seated with a good jam.
It also seems to be that most rifles will also shoot at another load window around 1.2 grains lower, in my case that works out about right and it shoots just as well at around 28.6 - 28.8 grain with the 68's and around 29.0 with the 66's.
It has been my observation, which agrees with the comments of others, that the load in the 30.0 grain range will hold tune and be less fussy to the effects of ambient condition changes than the lighter load will, even though when in tune the lighter load may shoot fully as well.
Bullets with longer bearing surfaces such as those with lower number ogive shapes may build more pressure for a given load when compared to a double radius style bullet like the Ultra's or Bruno 00's. As such these loads may or may not apply and it is obviously wise to start low and work up.
Like I said, I am no expert but 30.8 grains of N133 sounds like a whole lot of powder and like Jackie said, the hard bolt lift is telling you that you are probably producing to much pressure. I've personally used up to 30.4 with a 66 grain Ultra for over 3400fps but wasn't in a big hurry to keep going past there !
Bryce
