View Full Version : Magnum Primers needed???
05-07-2005, 10:09 PM
I'm finally getting around to reloading for my new 300 Win. I was just wondering if it is best to use the magnum primers or are standard ok? Does anyone know how much difference the mag primers make?
05-08-2005, 09:39 AM
This is yet another of those perennial Ford/Chevy questions to which there is no set answer.
In most cartridges, under most circumstances, with most powders and in most climate conditions, standard primers are perfectly adequate. But not all.
In most circumstances, with most loads, standard primers give smoother ignition and deliver cleaner burning, smaller pressure/velocity variations and better accuracy. But not all.
My general and entirely personal rules call for standard primers in all loads. But I shoot smallish cartridges in warm weather.
If your powder charge is larger than 65 grains, and especially if you use spherical powder, OR if you usually hunt/shoot when it's below zero temperature, then you MIGHT have better results with magnum primers. But it isn't guaranteed.
Some folks use magnum primers all the time; or always with spherical powders, no matter what case size or charge weight. That's OK, too.
The only firm rule is this: if you switch primers (or any other component) after working up a load to near maximum, you MUST back down the powder charge and re-test.
Bottom line? Your results may vary.
05-08-2005, 11:30 PM
i thought you were gona say mileage may vary.:cool:
05-15-2005, 08:12 PM
Rocky gave you alot of info, most of which wasn`t need for your question, :D , what I trying to say is that I would recomand useing mag. primers in the .300 unless you are wnating to work-up some varmint loads for use only in the summer time.
05-15-2005, 08:40 PM
From CCI's web page:
Q: What's the difference between a "standard" primer and a "magnum" primer?
A: A magnum primer provides a longer flame duration, a higher flame temperature, or both. In some primers (the CCI small pistol primers, for example) the magnum primer may have a thicker cup to better handle higher pressures. Use magnum primers only where recommended in published load data. Substituting a magnum primer for a standard one without a charge adjustment will nearly always increase pressures. We use Magnum primers in data development with many ball propellants, and with very large-capacity cases. They are also a plus when you are shooting in temperatures below 20 degrees F.
None of the loads I have tested with CCI 200 and CCI 250 primers have shown any statistically detectable peak pressure difference. That does not mean there isn't one, just that there isn't always one, and my small sample hasn't found those cases yet.
05-15-2005, 08:44 PM
Not much real information from me in this one, but I use Magnum primers in my .300 Win and regular in the rest of my rifles. I started to work the loads for the .300 with magnums because that was what my loading manuals had used, and although lots of components have been tried, I haven't got around to experimenting with primers to compare them.
I also have not noticed any problem with either standard primers or magnums and cold, although all my really cold shooting has been done at game so my statistical sample isn't really that big. I just can't get motivated to go to the range when it's -25 or -30, but I will call coyotes or hunt deer at those temperatures.
Even when cartridges with standard primers are very cold, the gun has always gone "bang", and lots of animals have ended up shot (and some seemed just severely frightened. Hmmm.... should I blame my shooting or my primers?).
One day I will have so much time on my hands that I'll try some actual chronographing in extreme cold. Maybe.
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