6.5 PRC Pressure signs

[Schalla]

Hi,
I’m new to reloading for rifle calibers. I’m using White River Large Rifle Magnum primers, virgin Norma brass, 56 grains of N560, and 147 gr ELD-M bullets. The bolt lift feels heavier than with factory loads. The rifle has about 100 rounds through it. Are the extractor marks on the cases a cause for concern? Average velocity is 2901 fps.

Rifle:
Howa 24"
Long action
Suppressed

 

[aprocast]

You have very high pressure there.
Also I have found the Norma brass to be junk.
Neck splits after a couple of loads.

 

[tekmann2377]

Yes too hot, primer is flat and cratered too. Drop it a bit. Also you may get more velocity and less pressure from N565/H1000, they are a bit slower burning than N560. That being said, Norma brass is reputed to be rather soft too.

 

[straightshooter1]

Hi,
I’m new to reloading for rifle calibers. I’m using White River Large Rifle Magnum primers, virgin Norma brass, 56 grains of N560, and 147 gr ELD-M bullets. The bolt lift feels heavier than with factory loads. The rifle has about 100 rounds through it. Are the extractor marks on the cases a cause for concern? Average velocity is 2901 fps.

Rifle:
Howa 24"
Long action
Suppressed

You're charge weight of 56 grs of N560 fills Norma cases just fine and normally shouldn't produce a pressure issue, though that charge is just a bit on the warm side. But those ejector marks are a sure sign of over pressure that needs to be addressed. I think you have a combination of things, the main one being the use of magnum primers. With this size of cartridge, there's really no issue where you've need to use magnum primers with a powder that as fast burning as N560. . . unless you're shooting in very very cold conditions that might effect ignition. I've never used magnum primers in my 6.5 PRC and great performance out of standard LRP's.

If these were shot in pretty warm/hot summer temperatures, it would contribute some to increasing pressure since your load is a somewhat warm charge to start with. Then being suppressed can add to that too.

 

[spife7980]

OP, read this

https://primalrights.com/information/understanding-pressure

 

[Holliday]

You're charge weight of 56 grs of N560 fills Norma cases just fine and normally shouldn't produce a pressure issue, though that charge is just a bit on the warm side. But those ejector marks are a sure sign of over pressure that needs to be addressed. I think you have a combination of things, the main one being the use of magnum primers. With this size of cartridge, there's really no issue where you've need to use magnum primers with a powder that as fast burning as N560. . . unless you're shooting in very very cold conditions that might effect ignition. I've never used magnum primers in my 6.5 PRC and great performance out of standard LRP's.

If these were shot in pretty warm/hot summer temperatures, it would contribute some to increasing pressure since your load is a somewhat warm charge to start with. Then being suppressed can add to that too.

I am running cci br large rifle standard primers with n560 and 143 bondstrikes, ADG brass at 2992 fps in my 24” 6.5 prc with no pressure issues.

I agree I would try standard primers. Better brass too……

 

[Schalla]

Thanks, I am in South Africa and shooting supplies are rather expensive, I know a direct conversion to USD is not comoletely accurate but 100 Lapua cases are about $280, I payed about $120 for a 100 Norma cases

 

[Schalla]

Yes too hot, primer is flat and cratered too. Drop it a bit. Also you may get more velocity and less pressure from N565/H1000, they are a bit slower burning than N560. That being said, Norma brass is reputed to be rather soft too.

Sweet thanks I will switch N565

 

[Tugboater]

It could also be that you have a carbon ring built up in there.

I developed a pretty good carbon ring in my 6.5 PRC shooting suppressed.

 

[straightshooter1]

Thanks, I am in South Africa and shooting supplies are rather expensive, I know a direct conversion to USD is not comoletely accurate but 100 Lapua cases are about $280, I payed about $120 for a 100 Norma cases

Just be aware, should you change cases, Norma case tend to have more case volume than others; like there 2-3 grs move volume than Lapua. So, if you use the same charge in Lapua, you'd be getting substantially more pressure.

Sweet thanks I will switch N565

My favorite powder for my 6.5 PRC is the N565. I think you'll like it!

 

[Holliday]

Just be aware, should you change cases, Norma case tend to have more case volume than others; like there 2-3 grs move volume than Lapua. So, if you use the same charge in Lapua, you'd be getting substantially more pressure.


My favorite powder for my 6.5 PRC is the N565. I think you'll like it!

Yep same with ADG.

Do you get the same velocities with N565 as with N560?

One thing that chaps my ass with N560 is that they advertise it as “temperature stable” which is an outright lie. A cursory google search shows this to be a fallacy. My controlled testing corroborates it.

30 fps in a 37°f temp change is hardly “temperature stable”. That’s a “Vihtavuori LIE” is what that is.

 

[Schalla]

Yep same with ADG.

Do you get the same velocities with N565 as with N560?

One thing that chaps my ass with N560 is that they advertise it as “temperature stable” which is an outright lie. A cursory google search shows this to be a fallacy. My controlled testing corroborates it.

30 fps in a 37°f temp change is hardly “temperature stable”. That’s a “Vihtavuori LIE” is what that is.


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I have only used N560, I am planning on switching to N565 and CCI Large rifle primers, based on the advice that I have gotten in this thread.

 

[straightshooter1]

Yep same with ADG.

Do you get the same velocities with N565 as with N560?

One thing that chaps my ass with N560 is that they advertise it as “temperature stable” which is an outright lie. A cursory google search shows this to be a fallacy. My controlled testing corroborates it.

30 fps in a 37°f temp change is hardly “temperature stable”. That’s a “Vihtavuori LIE” is what that is.


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I've not used N560 myself, so I not sure how it compares to N565 other than what I see published where N560 had a significant higher burn rate. I'd expect higher pressure and velocity with N560 than N565???

I use N565 to push 142 SMK's and Berger 153.5's. For both of them, I get good results out of my 26" barrel with an MV of ~2,980 fps.