Pressure ladder work up 6.5 prc

[Ranger 692]

Did my initial pressure testing from 55-57.5 gr of H1000 today with 147 ELDMs in 2nd firing Hornady brass. 14 degrees. There was definite ejector marks at 57.5, some at 57, bolt lift got slightly heavier at 56.5+. Pic attached 55-57.5 left to right. Never really saw much pressure signs reloading for my 7mm-08. How much is too much as far as swipes/ejector marks go? Speeds were:
55 gr 2745
55.5 2747
56 2796
56.5 2808
57 2824
57.5 2875

 

[amassi]

Too many variables to use swipes and ejector marks as indicators. Different actions, head space, distance to lands et el will all affect when it happens. I’ve seen 75k psi loads leave no indications of pressure and 55k look like primers were about to leave.

I’d load 20 at 56.0 and see how it shoots for group
It’s 1.5g below Hornady book but a flat spot in your ladder you should be plenty safe when it warms up.

For giggles what’s your rifle details
action, barrel length, suppressed? How far from the lands are you?


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[Ranger 692]

Too many variables to use swipes and ejector marks as indicators. Different actions, head space, distance to lands et el will all affect when it happens. I’ve seen 75k psi loads leave no indications of pressure and 55k look like primers were about to leave.

I’d load 20 at 56.0 and see how it shoots for group
It’s 1.5g below Hornady book but a flat spot in your ladder you should be plenty safe when it warms up.

For giggles what’s your rifle details
action, barrel length, suppressed? How far from the lands are you?


Sent from my iPhone using Tapatalk

Tikka action that used to be a 300 wsm, 22” barrel, AB Raptor 8 can. No idea on distance to lands, I’m loading exact same length as the factory Hornady 147 eldm ammo since that’s what I’d been shooting with very good accuracy.

Haven’t chrono’d the factory stuff yet since I just got the Athlon rangecraft on Black Friday.

 

[amassi]

Tikka action that used to be a 300 wsm, 22” barrel, AB Raptor 8 can. No idea on distance to lands, I’m loading exact same length as the factory Hornady 147 eldm ammo since that’s what I’d been shooting with very good accuracy.

Haven’t chrono’d the factory stuff yet since I just got the Athlon rangecraft on Black Friday.

I’d go test that 56 group and see what you’ve got


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[TaperPin]

I’ve had soft brass leave more than half dozen ejector marks and still had tight primer pockets and lasted over ten reloads, so like was said above slight marks by themselves don’t tell the story, but you’re up to where max is floating around somewhere close. Soft brass work hardens every firing so each time the marks will be less visible. Primers don’t look bad by themselves. You could pick any of those and just see how long the brass lasts and adjust if needed. If primer pockets get loose, or the case head starts to show separation rings in under 10 shots I back off a little.

 

[Ranger 692]

Regarding the case head separation rings, this is the 57.5 gr case, slightly has a visible ring. Is this an issue? Or maybe something I did resizing? I bought the Hornady dies for 6.5 prc and just followed the book instructions. I will say the once fired factory cases look the same

 

[TaperPin]

Regarding the case head separation rings, this is the 57.5 gr case, slightly has a visible ring. Is this an issue? Or maybe something I did resizing? I bought the Hornady dies for 6.5 prc and just followed the book instructions. I will say the once fired factory cases look the same

View attachment 984503

A separation ring happens where pressure holds the upper part of the case tight to the chamber walls as the thicker head of the case is pushed hard against the bolt face causing the transition area to stretch and thin out. More pressure or more headspace causes it to thin more quickly.

If you are ever curious what a ring is, a paper clip with bent end will easily feel the thinning spot well before it’s visible on the outside of the case.

 

[Ranger 692]

A separation ring happens where pressure holds the upper part of the case tight to the chamber walls as the thicker head of the case is pushed hard against the bolt face causing the transition area to stretch and thin out. More pressure or more headspace causes it to thin more quickly.

If you are ever curious what a ring is, a paper clip with bent end will easily feel the thinning spot well before it’s visible on the outside of the case.

View attachment 984509View attachment 984510

View attachment 984511

Ok did that, couldn’t feel any valleys. Thanks

 

[TaperPin]

When a separation is about to happen it’s usually easy to see the ring, but if you miss it and the next time it’s fired the case head does have a partial separation, it will most likely look like one of these and no harm done. It’s good to not make a habit out of letting them separate because there is a chance the entire front of the case will be left in the chamber. I just visually check cases each reload and cull out any with obvious rings.