Home Forums Reloading Big Game Rifles Why Magnum Primers in a .308 Winchester????

In looking at various sources of .308 Win. data, I'm finding that many use magnum primers for this medium-capacity round. Nosler uses them exclusively. Speer's data uses them for loads with ball powder. Hodgen uses them. Why? I don't think I've ever seen them called out for the '06 or the .270. My understanding is that magnum primers are only required with large charges of slow burning powder. 40-50 grains of a medium burn rate powder doesn't seem to warrent their use. Is there something I'm missing here? Thanks.

Lots of ball powders used most likely.

I think you're reading the Federal 210M in Nosler's data as magnum, but the 210M is the Match version of the regular large rifle 210. The Federal large rifle magnum is the 215 and the magnum match is the 215M.

Yep MM, I think you are right -- Federal 210M listed. I don't have the manual handy so I'll have to check tonight. But, I do seem to recall a statement to the effect of "we had best results using magnum primers," in the write up. And, I'm certain about Speer using magnum primers for ball powder loads (CCI), which makes some sense I guess. (I'm new to reloading rifle, so I've got LOTS of questions). I'm thinking of working up similar loads with both types of primers to see if I get any difference in standard deviation or accuracy. Also, because I live in Minnesota, loads need to work consistantly over about a 100 degree temperature range. Again, I'll have to see how they compare -- the magnum primers might help in the cold (as will, I presume, using Hodgdon Extreme powders). Thanks for your response.

Yes Speer does use magnums with ball powders. The standard CCI 200 is generally regarded as a mild primer, so that's probably why.

In contrast the WLR is a relatively hot standard primer and lights off ball powders no sweat.

You don't need magnum primers until you reach 70 grain of powder. Standard primers work ok in everything up to the 7mm and 338 mags.

AGW

Some labs have the groundrule of using mag primers with ALL spherical powders, no matter what.

In practice, they aren't really needed with ALL sphericals, and aren't needed even with the hard to light ones in cases of less than about 60 grains water capacity.

But they seldom hurt anything IF you have started using them from the lowest startup load. Changing later might be unwise, though.

Sometimes they will produce better accuracy even in smaller cases, especially with ball powders. I have seen this several times with Ramshot powders, for instance.

I use WLRM primer in my 25/06 and WLR in my 300WSM loads. Tried the reverse but got better results, chrony/accuracy, with the aforementioned.Rick.

I used to like CCI 250s when I used WW748 in my 308 a while back.

I use WLRM primers whenever I load W-760/H-414 in my 7-08. Accurate, excellent velocity, and burns surprisingly clean.

WW748 was the classic powder for teh .308 until VARGET came along.

48gn 748 with the 150 grain bullet and go deer hunting.

AGW

Do the use of magnum Primers in a smaller case have anything to do with the temp.???

The magnum primer is hotter so a reduction in powder charge is appropriate in smaller cases.

AGW

Yes, I double-checked and that is the case. Hodgdon also references the Fed210M. So, I carelessly misread the data -- not a good thing to do, for sure.

I've found some scary stuff on the net regarding primer substitions. But, it does seem like experienced reloaders WILL make substitions (backing off the charge and working up again anyway). It doesn't seem to me that in something like the .308, working with starting loads, it would be catastrophic. Am I just looking for trouble by not following the EXACT recipes in the books?

Thanks for your replies -- I appreciate the input of guys who've been doing this for some time.

In one sense a primer is a primer....in another its not. If a mag primer needed, then it is. If it's not needed but used, it wont hurt...either could affect accuracy.

I'm with 280 on a "primer is a primer" but I'll add that it is rifle to rifle types. Pistol to rifle and vice versa is a whole different matter (hopefully I'm stating the obvious). A primer is another piece of the accuracy puzzle. I've tried different makes, both magnum and regular in my all my 308 based rounds. You are safe as long as you work up new loads with any new component. For example, I was working up loads for my 338F and was using W748 with CCI 200s and WLR primers (both non magnum). With WLR primers, pressure signs showed way before I got to maximum book loads.

FWIW, I've found IMR4895 to be THE powder for 308 based rounds. It is what I used to use in my 308 when I had it. I also use it with my 7mm-08 and 338F. I use CCI200 primers - not magnums.

RH

Speer recommends magnum primers with ball powders. That is why I've used them. They do help with the "dirty" powder reputation that W-760 and H-414 have. This combo has left noticably less residue than extruded powders with non-mag primers in my two 7-08s.