Pressure or not?

[roklock]

Hello,

Working up a long range load for 300 wsm, newer model 70, coyote lite. using H4350 208 gr amax .010 off the lands. Norma brass

I am starting to see a shiny small rectangle (I'm guessing extractor) on the rim of the case BUT seeing no primer flattening and there is no issue with bolt left yet. Is this shiny rectangle saying stop?

The reason I am asking is the last two loads (62 & 62.5 grns) show the best promise to continue load development but trying to understand if I should abandon and try a different powder.

Thanks,

Steve

 

[Lefty7mmstw]

brass flow= overload.... you don't need to get hard bolt lift or primers smashed flat for an overload... You may not even be over 65KPSI, but your brass is saying "enough" and deforming... brass life will suffer

 

[Deleted member 46119]

What he said.

If you are accurate, stop, fine tune, enjoy.

 

[bruce_ventura]

A small tool mark on the case head, by itself, is not enough to indicate over pressure. A sharp edge, rust pitting, etc., on the bolt face can create a local pressure point that leaves a mark, even when the case pressure is well below max. I look for a another indicator.

In your case the charge weights are above max load in my Lee Handbook. In that situation I would stop at the first indication of over pressure, especially if I only saw the mark appear above 60 grains. What does your chronograph read?

 

[roklock]

In your case the charge weights are above max load in my Lee Handbook. In that situation I would stop at the first indication of over pressure, especially if I only saw the mark appear above 60 grains. What does your chronograph read?

Yes, I get all of the books show I am above max BUT I am loading longer than SAAMI and yes it is .010 off the lands so that may cancel each other out...below is my data from Chrono..

Grns 59.5 60 60.5 61 61.5 62 62.5
MV 2721 2741 2745 2777 2801 2808 2824
ES 67 12 19 35 23 29 18

 

[FEENIX]

Yes, I get all of the books show I am above max BUT I am loading longer than SAAMI and yes it is .010 off the lands so that may cancel each other out...below is my data from Chrono..

Grns 59.5 60 60.5 61 61.5 62 62.5
MV 2721 2741 2745 2777 2801 2808 2824
ES 67 12 19 35 23 29 18

Those are very nice MVs, what's your barrel length?

 

[roklock]

Those are very nice MVs, what's your barrel length?

24", it is a stock Model 70 coyote light, only thing (so far) I did was add a muzzle brake. Wanted a jewel trigger but they don't make them to replace MOA triggers

Also, for what it's worth it isn't a high end chrono, it is a CE Prochrono digital.

 

[bruce_ventura]

Yes, I would stop at 62 gr and check group size going down in charge weight.

Nothing wrong with that chrono. I have one. Very accurate in my tests. In this case, price is not a good indicator of performance.

 

[FEENIX]

24", it is a stock Model 70 coyote light, only thing (so far) I did was add a muzzle brake.

Cool, thanks! Mine is also a 24" and currently developing load for Berger 215s and might have to give a shot.

 

[Lefty7mmstw]

A small tool mark on the case head, by itself, is not enough to indicate over pressure. A sharp edge, rust pitting, etc., on the bolt face can create a local pressure point that leaves a mark, even when the case pressure is well below max. I look for a another indicator.

In your case the charge weights are above max load in my Lee Handbook. In that situation I would stop at the first indication of over pressure, especially if I only saw the mark appear above 60 grains. What does your chronograph read?

he said as he's working up.... he did not get the marking at lighter loads.
It's not a good idea to allow brass flow. There are a number of reasons.... premature brass failure, difficult action opening, brass shavings getting into the action/trigger, etc...
I'm sure that's not where you were going with playing devil's advocate that the pressure may be fine. I am just stating exceeding m.a.p. isn't the only reason to stop load development.

He's above book loads, getting brass flow marks, and getting rather high speeds... Time to back off a bit...