6.5 PRC Primer Standard vs. Magnum

[Rprecision]

I have around 25 shots through my R700 in 6.5 PRC. I am going to get 100-150 before I do any load work.

My intended load is 143ELDX, H1000, Hornady Brass, Fed210M.

I loaded up some test loads to start break in and loaded from 56.0 to 58.5 to get a feel for pressure. At 58.5 (3 rounds) I noticed a pile of carbon, partially burned powder in the lower lug recess just outside the chamber. Think cat litter size. Nasty crap crushed in the action.

I never hit any pressure issues and had great accuracy, but this has had me seriously thinking about primer choice. All the literature I can find calls for a standard rifle primer.

I looked at the .300 RCM which the parent case to the 6.5 which calls for a magnum primer. I looked at all the flavors of short magnums WSM, SAUM and they all call for a magnum primer. I specifically looked at those cartridges in the 60ish grain territory and they all call for magnum primers. Perhaps the only outlier is the 6.5-284 and the 06' family of 6.5 Wildcats.

I tested some loads at 57.5 today and ran into the same unburned powder crud. Not as bad but

definitely there. As a aside this is fresh powder, primers are kept sealed up and 6 months old.

The only thing I can find on the topic is here:

https://www.snipershide.com/shooting/threads/6-5-prc-load-data.6902053/

And a discussion:

"Handloaders will get the best out of it using relatively slow-burning propellants like H1000, Reloder 26, and IMR 7828. However, unless charge weight exceeds 60 grains, handloaders are best served with standard Large Rifle primers rather than Magnum primers, unless the ammo is intended for a hunt in extreme cold, in which case Magnum primers offer a bit more consistent ignition."

Has anyone encountered this problem with the PRC ?

I attached some pictures to give a sense of what I'm talking about.

Thanks

 

[shoot4fun]

My buddy and I have rifles chambered at the same time with same reamer. He shoots H1000 with standard primers and 153 A-Tip and I shoot Retumbo with magnum primers and 153 A-Tip. Both rifles are very happy with their respective diets and neither of us have seen anything like the carbon issue you see.
Both of started with the 140 ELDM but the A-Tip is out performing it by a bit.

 

[Rprecision]

I have never tried standard vs magnum primers in a cartridge. Is dropping 10% ok or is that unnecessary?

 

[Steel head]

I use regular large rifle primers in my 7 saum.
I had great results even when it was high teens low 20’s temps.

I can’t see carbon from firing getting there without really low pressure or leaking primers and even then I can’t see that amount.

I think a carbon gremlin pooped in your lug recess when your weren’t looking.

 

[Steel head]

I have never tried standard vs magnum primers in a cartridge. Is dropping 10% ok or is that unnecessary?

If your load is on edge with regular primers you can absolutely find pressure issues with a magnum primer.

 

[Mconrad33]

I have 3 different custom 6.5 PRC's and have loaded extensively for all 3 of them in the 140 gr projectile range. I have compared standard primers vs. magnum primers in numerous handloads. The VAST majority of the time the standard primers offer more accuracy, lower ES and SD. The magnum primers are not necessary for a 6.5 PRC.

 

[acourvil]

I tried CCI BR2 and CCI 250 (magnum) primers in my 6.5 PRC. I had trouble getting the SDs down to 10 with the magnums, typically 15 was where they ended up. With the BR2s i was able to get the SDs to 10 or less. Average speed dropped 5-10fps, but the SDs were consistently better,

 

[Mconrad33]

I have had the same results. Thanks.

 

[Eeegadd]

My buddy and I have rifles chambered at the same time with same reamer. He shoots H1000 with standard primers and 153 A-Tip and I shoot Retumbo with magnum primers and 153 A-Tip. Both rifles are very happy with their respective diets and neither of us have seen anything like the carbon issue you see.
Both of started with the 140 ELDM but the A-Tip is out performing it by a bit.

What are the fps for the retumbo vs h1000? Thanks