Magnum Primers?

[nvshooter]

What's your opinion regarding using Large Rifle Magnum primers to ignite the powder in the 6.5mm Creedmoor case? I have no standard-power LR primers and I'd bet the farm that Scheels doesn't have any, either...

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[Whisky Tahoe]

What's your opinion regarding using Large Rifle Magnum primers to ignite the powder in the 6.5mm Creedmoor case? I have no standard-power LR primers and I'd bet the farm that Scheels doesn't have any, either...

LRMs can certainly have an effect on a load compared to normal Large Rifle primers.
On other forums, folks have posted their results from testing 6.5CM with magnum primers. A few use magnum primers by choice.
1) The extreme spread of the velocity seems larger with magnum primers.
2) Ball powders displayed more sensitivity. H4350 is extruded.

If the load is worked up from a safe margin, it can work. Might not be recommended (because it hasn't been tested) but that is what you will be doing.
Note that the difference in velocity isn't always obvious. With 6.5CM small primer brass, I tested normal small rifle primers compared to magnum small rifle primers I noticed a 25 fps speed increase using the normal BR4 primer versus the 450 magnum primer. I guessed it was the BR4 allowed the pressure to build a smidge (technical term) slower and resulted in more speed compared to a faster pressure wave and a little slower velocity. Like I said it was a guess.
I measured 50 rounds with 25 of each and that was the average speed delta.

On a side note, Temperature can have a larger impact on velocity/pressure depending on the powder.
With older N160 before it was formulated to be more temp stable, I measured 75 fps increase over a 40 degree temperature rise (50 degrees vs 90 degrees)
6SLR (243 clone) with 105gr Hybrid, Fed 210M and Lapua brass sized, turned

 

[nvshooter]

LRMs can certainly have an effect on a load compared to normal Large Rifle primers. If the load is worked-up from a safe margin, it can work.

I'm guessing the LRM primer throws a larger flash through the powder column. I doubt the temperature of the flash is a lot higher than the flash from a standard-power primer-- just that the flash is larger. A "bigger bomb," if you will. Part of my case prep is to chamfer the inside of the primer hole. I'm telling myself the chamfered hole will allow for the flash to spread itself into a wider funnel. The chamfering tool also enlarges the primer hole a bit, making it identical from case to case. All my cases are trimmed to the length the Lee Precision case trimmer provides. All the mouths of all the cases are chamfered inside and outside. Just waiting on what our members have to say about the possible use of Magnum versus Standard primers before we take the next step...

 

[dangerranger]

Mag primers don't have a larger flash or more power. They work on magnum loads of slow burning powders by providing a longer burn. instead of a quick flash they provide a longer extended burn. compressed loads of slow burning powders are the hardest to ignite. And the longer burn does a good job of that.
Other than the higher cost I would not avoid using them in standard loads. DR

 

[nvshooter]

Mag primers don't have a larger flash or more power. They work on magnum loads of slow-burning powders by providing a longer burn. ... Other than the higher cost, I would not avoid using them in standard loads.

Alrighty, then! I'll use the Large Rifle Magnum primers I have. I'm not concerned about their high cost: I guessing I paid fifteen to twenty dollars for the 1000-count box I've had since January of 2007.

 

[Whisky Tahoe]

More background on primers...

Mysteries And Misconceptions Of The All-Important Primer - Shooting Times

By Allan Jones Most component primers have a little disk of paper between the

www.shootingtimes.com

CCI spokesman comments on Magnum Primers:
Magnum Primers
There are two ways to make a Magnum primer — either use more of the standard chemical mix to provide a longer-burning flame or change the mix to one with more aggressive burn characteristics. Prior to 1989, CCI used the first option in Magnum Rifle primers. After that, we switched to a mix optimized for spherical propellants that produced a 24% increase in flame temperature and a 16% boost in gas volume.

As Forest might say...
That is all I have to say about that...