6.5 PRC over pressure signs

[Rocketeer77]

Have a budget build with a Howa action & barrel, laminated glass bedded stock along with a decent Bushnell scope. With 130gr ELD-M projectiles and 57gr of H1000 powder new Norma brass it groups very well at around 0.5 MOA and that's after only thirty off rounds from new, average velocity seen is 2,900 FPS with only 16 FPS velocity spread. But seeing quite heavy bolt lift, rear of cases marked and flattened primers (not too bad). I have some unused Hornady factory rounds 143gr ELD-X. So it looks like excess pressure signs along with slower velocities than I expected.

Would like to hear your thoughts on possible issues, again it's only had thirty rounds through a new OEM barrel

 

[257 STW]

Pics of the case heads, and primers would help us, help you. Heavy bolt lift, along with ejector marks or swipes is usually a red flag for pressure. Velocity falling off is a pressure sign as well.
Hornady shows 59.0 with a 143 ELD as a max load with H1000, so I would think you should be fine with a 130. But! That`s with Hornady brass. Your Norma brass could have a smaller case volume due to being thicker brass. Back it down a couple grains and see what velocity does, and if your pressure signs go away. Just a thought.

 

[257 STW]

Another thought was how far off the lands are you? If your jammed you could create pressure as well.

 

[Rocketeer77]

Another thought was how far off the lands are you? If your jammed you could create pressure as well.

Will check actual distance to lands, was running slightly under max COL, will get photos of case Bases.

 

[257 STW]

Will check actual distance to lands, was running slightly under max COL, will get photos of case Bases.

I run Ramshot Magnum in my 6.5 PRC with a Berger 156 EOL at 3003 AVG. I have heard H1000 will sometimes pressures out sooner than expected as well, but that is second hand info as I have never tried H1000 in my PRC so don`t quote me. Is there a reason you want to run the lighter 130s? Either way you have a pressure issue, and you are aware of it so lets get some others to jump in and see if we can help you figure it out. Couldn`t really find any load data on the HDY 130 ELDM, But Nosler says 60.0 MAX H1000 with their 130s FYI. I also know that VV N565 works well with the heavies in 6.5 PRC. You may have to try some different powders if your set on 130 class bullets. And as I said before your case volume could be very different between Hdy and Norma brass.

 

[Kmccord]

See Hodgdon load data with H1k and a 130gr., it is not the ELD-M, but they list 58.9 and it was compressed. Like others have said, what is your distance to lands, if jammed that will create pressure.

Reloading Data Center

www.hodgdonreloading.com

 

[cjl2010]

Did you clean it and leave solvent in chamber?

 

[BEEMAN]

What's your barrel length? I don't have a 6.5 PRC, but that does seem slow. I have two 6.5x47's. One shoots the 130 Berger at 3000 FPS. Other one shoots a 124 HH at 2938 FPS. Barrels are 26" and 25". I'm no expert but is it a brass issue like trim length or a headspace problem? Tight necks etc?

 

[Rocketeer77]

I run Ramshot Magnum in my 6.5 PRC with a Berger 156 EOL at 3003 AVG. I have heard H1000 will sometimes pressures out sooner than expected as well, but that is second hand info as I have never tried H1000 in my PRC so don`t quote me. Is there a reason you want to run the lighter 130s? Either way you have a pressure issue, and you are aware of it so lets get some others to jump in and see if we can help you figure it out. Couldn`t really find any load data on the HDY 130 ELDM, But Nosler says 60.0 MAX H1000 with their 130s FYI. I also know that VV N565 works well with the heavies in 6.5 PRC. You may have to try some different powders if your set on 130 class bullets. And as I said before your case volume could be very different between Hdy and Norma brass.

I have four powders that will work in this cartridge, just did something conservative here to 'run it in' will weigh the Norma brass to compare with Hornady. The low velocity doesn't gel with high pressure (to me anyhow?) but I don't pretend to be an expert. The 130's were from my 6.5 x 55 SE but like the USA we're using what we can Get nowadays. Have some Hornady 140gr match BTHP also with 57gr of H1000 but not used as yet.

 

[Rocketeer77]

What's your barrel length? I don't have a 6.5 PRC, but that does seem slow. I have two 6.5x47's. One shoots the 130 Berger at 3000 FPS. Other one shoots a 124 HH at 2938 FPS. Barrels are 26" and 25". I'm no expert but is it a brass issue like trim length or a headspace problem? Tight necks etc?

24" sporter type, but groups very well regardless? Brass is slightly short from new around 0.010" one thing I noticed was the fired brass neck ID was .264" exact size of projectiles maybe a tight neck? Will do some more measurements

 

[257 STW]

Velocity might not fall off much, but I have seen when going up in charge weight when above max the velocity will actually go down instead of progressing up. If this happens you are past your max charge weight and into the danger zone. I have had it happen a few times over the years, and have read of others experiencing it as well. Just my .02

 

[kiwikid]

The ID of .264 on a fired case may well be the cause of the pressure signs you are seeing.
If it were me I would measure the OD of a loaded Norma case and compare that to one of you unused Hornady factory loads. This will give you an indication as to whether the Norma neck thickness is the issue or if you have a tight chamber neck.

 

[MagnumManiac]

Norma brass is guaranteed to have MORE capacity than any other brand…your reduced velocity tells you this.
As you have had only 30 rounds down the bore, there still might be burrs in the chamber causing your issue.
Whenever I see ejector swipes on new rifles and new unfired brass, I check the headspace, if it's tight, it can cause your symptoms too.

Cheers.

 

[Rocketeer77]

Measured the new Hornady rounds at the neck with 143 ELD-X and diameter is 0.292" the Norma is slightly larger by only 0.001" this is the brass OD. The projectile (130gr) is perfect at 0.264" the specifications for this neck diameter are 0.297"
Powder to hand is H1000, H4831SC, N565 and AR2217 that suits this cartridge. I lightly oil the bore after cleaning using a bit on a small patch, in theory this could run down the barrel into the chamber while being stored?
Fired cases measure 0.523" at the projectile end and before firing are 0.513" Norma & 0.515" OD with Hornady (specification = 0.5166") so a ten thou increase while the bases go up by only four thou post firing.