Magnum primers for .308

1/2 MOA

1/2 MOA

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How many of you are running mag primers in your .308's? What results are you getting, if any?


I have been using Lapua brass, Federal gold medal match large rifle primers, Varget powder and Lapua 155 gr Scenar's. I have a compressed load right now, if I switch to mag primers and have to back my load down a half a grain or so it might help. Thought the mag primers might help in the cold weather this winter.

Thanks in advance. :D
 
Thanks Slapshot,

I just started using magnum primers when I use ball powder. I use Win 760 and mag primers in my .243 now. I also recently bough a .223 and was talking to Jerry and he suggested I use CCI mag primers in it to help out in the cold weather. I just always have ran large rifle primers in my 308.
 
I personally have used both and to tell the truth ... seen no difference.
I load 47 Gr. IMR 4831 with 165 gr. Nosler Partition Spitzer.

Love the groups I used to get when I was shooting more.

CT
 
A couple of years ago I tested various primers, looking for the most uniform velocities I could get. It was a .308W, using Lapua brass, a Lapua 155 Scenar at about 2.840", and about 45 grains Varget.

Federal GM215M were not much better or worse than the others I tested (F210M, KVB-7, WLR-M, R9.5, RWS5341, etc). What surprised me was how little extra velocity they produced compared to the other primers I tested (about 20-ish fps). You might find that you don't need to reduce your charge by 0.5 grains, if you even have to reduce it at all (but starting off 1/2 a grain off is probably the right thing to do).
 
The rule of thumb I have followed is to use a magnum primer with ball powder (except in small capacity cases like the .222) when the powder charge exceeds 50 grs, and in cold (sub-zero F) temperatures. Since I've lived in the north, it's been just simplier to load everything except match ammo with the magnum primers.
 
I wouldn't even dream of reducing a load of 4831 in a 308 with 165 grain bullets, because I changed to a magnum primer. Any load of 4831 in a 308 is not going to be a high pressure load.
 
When I was doing load development I could not fit enough Varget powder in the case to give me pressure sighs. So from what you guy's are saying there will be no real advantage to using mag primers. Except for cold weather and that I will probably end up with around the same powder load

Boomer, why do you not use mag primers in you match loads?
 
1/2 MOA said:
Boomer, why do you not use mag primers in you match loads?
Click to expand...

I suppose because I am gullible enough to believe the advertising around bench rest primers.

Primers are the one element that we don't have much control over. We can measure bullets in all sorts of ways, we can carefully weight our powder, and we can lovingly prep our brass until each piece of brass for each group is a clone of the others loaded for that group. Visually it is difficult to tell a good primer from a dud. Weighing them doesn't tell you much as variations in weight could be differences in the cups, anvils, the priming mixture of each primer, or a combination of variances amongst all these elements.

When I load match ammo, I want a primer that will reliably ignite the powder column with the minimum amount of violence, and I want each primer to be a clone of the primers in that lot number. The manufacturers tell me match/bench rest primers are more consistent than standard primers and because I am at their mercy, I believe them.
 
I tried using mag primers in my 308 Win for a while at the insistance of a buddy of mine that my ammo would not go 'bang' in cold weather if I did not. I did two 12 shot targets -- one with mag primers, one with standard primers -- same bullet/brass/powder in both (Varget). The mag primers produced a significantly (and consistently) larger grouping than the non-mag primers did;enough so that I considered it well outside the variable of my shooting skills. I have since reverted to non-magnum primers (CCI 200's) in my 308 Winchester, and have had zero 'bang' failures, even in cold weather (-25 is about as cold as I've ever tested though).
 
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