Extractor Marks?

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Stammster

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One reason the primers are cratered is because it was shot from a Rem action/ bolt with a sloppy firing pin hole. That can occur even with safe loads. This is the reason primer cratering is a bad sign of pressure. Primer piercing is a sign of pressure.

Ejector marks on the case head are usually a pretty good sign of excess pressure - but I’m surprised you didn’t feel any excess bolt lift.

Thus the question on lube in the chamber or on the cases is a good question - as this can result in the condition above even at acceptable pressures due to thrust.

Kind of hard to tell, but the primers don’t look too flattened on the edges, which I also observe when overpressure.

In summary, I’m not convinced this is excessive pressure.

I would clean the chamber with a chamber brush/swab using solvent that doesn’t leave any residue. I know you said it was clean and dry, but are you sure. Also remove all lube off the cases.

If the problem still exists, then back off the charge weight.

Also what is your barrel length and velocity? Barnes lists 3210 fps in 24” barrel at max charge compressed with 68gr RL17. Velocity comparison to the above will also give you a clue of whether you are under or over pressure.
 
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MT257

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One reason the primers are cratered is because it was shot from a Rem action/ bolt with a sloppy firing pin hole. That can occur even with safe loads. This is the reason primer cratering is a bad sign of pressure. Primer piercing is a sign of pressure. Ejector marks on the case head are usually a pretty good sign of excess pressure - but I’m surprised you didn’t feel any excess bolt lift. Thus the question on lube in the chamber or on the cases is a good question - as this can result in the condition above even at acceptable pressures due to thrust. Kind of hard to tell, but the primers don’t look too flattened on the edges, which I also observe when overpressure. In summary, I’m not convinced this is excessive pressure. I would clean the chamber with a chamber brush/swab using solvent that doesn’t leave any residue. I know you said it was clean and dry, but are you sure. Also remove all lube off the cases. If the problem still exists, then back off the charge weight. Also what is you barrel length and velocity? Barnes lists 3210 fps in 24” barrel at max charge compressed with 68gr RL17. Velocity comparison to the above will also give you a clue of whether you are under or over pressure.
24" factory barrel. I was getting 3299fps. Of the 5 shots my spread of velocities all 3300,3299,3301,3298,3297. Temp was 30.2 degrees F, 3.6NNE mph wind. Again the bolt lift was not stiff at all. Chamber has been swabbed out with brush and then a completly dry swap after. Don't believe the lube is a factor as that gets washed off in tumbler. This is the group that has been produced with this load. And I’ve replicated these results.
1459B3A2 5F22 49AE 8E20 011050355A12
 
PddPdd

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Do you have any other brass of a different brand? I would try reloading with higher quality brass at the same velocity node and see if the pressure signs persist.

How much slower is the next slower velocity node?
 
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MT257

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Do you have any other brass of a different brand? I would try reloading with higher quality brass at the same velocity node and see if the pressure signs persist.

How much slower is the next slower velocity node?
I tried the same load with Winchester brass. The results were not as good as the group I posted. The velocity of the Winchester brass was 3274.33 FPS. There were very faint marks on the head stamp.

I am unsure of what the next slower velocity node is.
 
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MT257

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Also, your COAL seems pretty long for a minimum of a .050” jump. Barnes data lists COAL at 2.735” with the 165 gr TTSX. I’d probably back off charge and check your jump to the lands.
The COAL is what fits in the magazine of the rifle. SAAMI spec for OAL on the 300WSM is 2.86".
 
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Stammster

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Based on your response concerning clean chamber and brass along with the velocity data, I would say you are over pressure.

If this is a 1-2 shot a year hunting load, then I wouldn’t be worried - except if you get into hotter weather.

What happens to your accuracy and ES if you back down to 3200 fps? Another way to ask is how did this shoot when you were working up to 68gr?

I’m sure you know you are trashing your brass and my guess is the primer pockets will loosen in a few loads.
 
Reelamin

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I load for three stainless stock 700’s In same chambering. As said you have primer flow back around the firing pin. The ejector marks are there also and the two together I think your a little hot. I like mine on the hot side if it still shoots fast and accurate enough. I would back off one grain and run it again. Even if you get a light ejector mark and no primer flow with your accuracy and velocity wants I would stuff em and use em.
 
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Muddyboots

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Barnes shows it is a max load for RL17but mono's may not always get to max. Agree with other recommendations to back off a bit. One thing I will advise is the Hornady brass will show signs of web expansion if you keep pushing their brass at this pressure signs. Just a heads up.
75D4D7CD A838 4804 B2D7 B0F39926EB7E
 
PddPdd

PddPdd

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I tried the same load with Winchester brass. The results were not as good as the group I posted. The velocity of the Winchester brass was 3274.33 FPS. There were very faint marks on the head stamp.

I am unsure of what the next slower velocity node is.
You might need to bump up your powder with the Winchester brass as it may have a little more case volume than the Hornady brass judging by the lower velocity.

If you try this, compare the same velocity fired Winchester brass with your Hornady brass to see if there pressure sign appearance differences.

BTW, I would look for Norma brass to increase longevity with hotter loads.
 
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MT257

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Based on your response concerning clean chamber and brass along with the velocity data, I would say you are over pressure.

If this is a 1-2 shot a year hunting load, then I wouldn’t be worried - except if you get into hotter weather.

What happens to your accuracy and ES if you back down to 3200 fps? Another way to ask is how did this shoot when you were working up to 68gr?

I’m sure you know you are trashing your brass and my guess is the primer pockets will loosen in a few loads.
Its simply a hunting load. The hornady brass shoot consitently like this, I did have a load of 66.4 that was just slightly less accurate but not by much. I don't recall if there was ejector marks. The winchester brass I have was roughly 7 grains lighter than the hornady brass, which would mean I can stuff more in the case not by much but some. I did shoot the exact load as I stated above with the winchester brass and there were slight ejector marks. I also bumped it up to 68.2gr and ejector marks were like those in the picture, but the accuracy was not.
 
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MT257

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You might need to bump up your powder with the Winchester brass as it may have a little more case volume than the Hornady brass judging by the lower velocity.

If you try this, compare the same velocity fired Winchester brass with your Hornady brass to see if there pressure sign appearance differences.

BTW, I would look for Norma brass to increase longevity with hotter loads.
With the velocity I shot 68.2gr with Winchester brass and it was slightly less than what the 67.9gr with Hornady brass was. But ejector marks were roughly the same in comparision. I think I will just have to back my charge down and end at 67.9 and work back in half grain increments.
 
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Stammster

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The other option to get to your 3300 fps node without pressure might be RL26.

Unfortunately you would need a “hot lot” of it to get those velocities - without running out of case capacity. The older RL26 lots (circa <=2019), seemed to be hotter than the newer 2020-2021.
 
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fmuguira

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As nwhunter mentioned and bucklowery mentioned….cratered primer on Remington not good indicator by itself. ( I have lots of those too) measuring web expansion from an unfired to once fired case will be a good indicator.

The fact your bolt isn’t showing lift tightness is a positive.

If you test expansion and elect to not back done I d suggest trying load on a warmer day too. That can give you another data point. The ES and accuracy is great for a ‘hunt in’ rifle !!

Good luck.
 

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