6,5x55

fiver

Well-Known Member
that is a big speed jump for one grain of powder with the N-150.
I'd be real leery right there, especially with no other steps to confirm what's going on there.
it may just be you caught the upper end of what could be velocity variations, or you have a pressure spike of some sort going on with that final jump.
 

Spindrift

Well-Known Member
Thanks for the tip, Fiver. I agree, the 34grs load may be a bit hot. I noticed some slightly increased resistance when opening the bolt also. No changes to the case head or primer. I have to take into account that I’m now doing load development in chilly weather- a slightly hot load in december could be worse in july.

It was encouraging to see that the bullets grouped reasonably well at this load level, though. I’ll try some slower powders, that I normally use for jacketed bullets; N160, imr 4831, Vec Tu-7000, MRP, maybe even Superformance.
 

fiver

Well-Known Member
that's one of the good things about using a chronograph.
it doesn't usually tell you a whole lot besides speed.
but it does act as an indicator when you see a big jump like that, or when adding more powder just levels off the speeds when your close to the top.
the level off thing is why you quite often hear guys talk about good shooting loads that are ''just a bit over book maximum.''
 

RBHarter

West Central AR
I had this Savage 06'.........

The best loads were always at start loads and 200 fps faster than book predictions for usually 2" more barrel , across 3 different Chronographs .

The sister rifle in 308 ........
Often was still closing groups ,speed wise, well into 06' 24" turf it was also faster by 150+ fps than book predictions . I could have taken that 150 gr likely 2950 fps ......
That rifle would not shoot anything over 175 gr .

That 308 , a BPS and an XD are the only ones of 70+ through the years that have thrived on anything approaching a max book load .