Primers ?
- Thread starter rebs
- Start date
BR-4 is not a magnum. Test whatever you have. Federal Gold Metal Match would be my first choice for replacement. Might want to work up the load as well.
As Donovan (@dmoran ) points out in a previous post, cup thickness is what primarily differentiates small primer models. All 'magnums' have 25-thou' thick cups whilst some 'standard' models are 20-thou, or 21-thou' in the case of the WSR. All so-called 'match' models are like magnums 25-thou', bar the Fed 205M (0.0225" thickness). SRMs do not necessarily have greater brisance than standards (unlike some LRM models).
You can find the performance a range of MVs 15 SR primers gave me in 308 Win Lapua 'Palma' with N150 here, and it is a small overall performance (MV) spread:
http://www.targetshooter.co.uk/?p=2662
The old PMC SR Magnum (Russian made Murom KVB 5,56M) is one of the mildest SR primers you'll find and contained the self-same explosive pellet as the standard KVB-223 model, but with a much thicker / tougher cup for use in 5.56 cartridges and other high-pressure loads.
What I have found over the years is that small cased SR primed cartridges - Grendel, 222/223, 6BR and so on, are very primer sensitive and often show a marked preference for one make/model over others. Most of these cartridges require a degree of 'retuning' the load combination on changing the primer. I wondered if it was just me and my prejudices, but Bill Alexander, creator of the 6.5 Grendel says the same thing of this cartridge and recommends trying every primer model available once a reasonably performing bullet/powder combination is found.
Unfortunately, primer manufacturers aren't always as consistent in their QC as we'd want, and it is not at all unusual to find significant performance differences between production lots of the same primer. So, in an ideal world, once you've found your great performer in a precision cartridge, you buy 5 or 10K of them all from the same lot. Not very practical or affordable in today's situation unfortunately.
You can find the performance a range of MVs 15 SR primers gave me in 308 Win Lapua 'Palma' with N150 here, and it is a small overall performance (MV) spread:
http://www.targetshooter.co.uk/?p=2662
The old PMC SR Magnum (Russian made Murom KVB 5,56M) is one of the mildest SR primers you'll find and contained the self-same explosive pellet as the standard KVB-223 model, but with a much thicker / tougher cup for use in 5.56 cartridges and other high-pressure loads.
What I have found over the years is that small cased SR primed cartridges - Grendel, 222/223, 6BR and so on, are very primer sensitive and often show a marked preference for one make/model over others. Most of these cartridges require a degree of 'retuning' the load combination on changing the primer. I wondered if it was just me and my prejudices, but Bill Alexander, creator of the 6.5 Grendel says the same thing of this cartridge and recommends trying every primer model available once a reasonably performing bullet/powder combination is found.
Unfortunately, primer manufacturers aren't always as consistent in their QC as we'd want, and it is not at all unusual to find significant performance differences between production lots of the same primer. So, in an ideal world, once you've found your great performer in a precision cartridge, you buy 5 or 10K of them all from the same lot. Not very practical or affordable in today's situation unfortunately.
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