magnum vrs. large rifle primers

jimmybirdwell · Rookie Member Joined: Jan 29, 2010 Posts: 4

Hello folks. very nicesite. thanks.
Can some one tell me the pro or cons of using magnum primers in place of large rile primers.
Jim

Bushmaster

In most cases magnum primers are not necessary unless the load data manual says so for a particular hard to start powder.

If you are going to use magnum primers in place of standard large rifle primers, reduce your powder charge by 10% (Do not go below minimum charge). Work up slowly watching for over pressure signs...

And...Welcome to this fine site. Grab one of Vince's beers, pull up a stump close to the fire and join right in...

Grumulkin

I frequently try magnum primers in cartridges where they're alleged not to be needed. Sometimes this substitution results in better accuracy.

It's alleged that magnum primers are needed with ball powders; this frequently isn't true and at times magnum primers give better accuracy with stick powders.

In medium sized (like the 308 Winchester) and larger cases, I've never had pressure problems in substituting large rifle magnum for large rifle primers.

gelandangan

I might be wrong, but I thought that magnum primers gives out larger flame and burns hotter,
therefore ensuring more powder grains burns in the initial ignition.
Hence higher pressure on the chamber due to more powder burns at the same time.l

Magnum primers also have thicker metal cup thus can withstand higher pressure.

gelandangan

Um, and aah.. Welcome to the site.

slimjim

gelandangan wrote:

Magnum primers also have thicker metal cup thus can withstand higher pressure.

I know very little about primers other than my standard CCI and Federal primers work good in the .243, .308, and .270 loads. I have heard other shooters say the above is the only real difference between a standard and magnum primer. Then I also hear they burn hotter. CCI says they burn 23% hotter with longer flame duration. Is it possible that the features of magnum primers vary from manufacture to manufacture or size of primer?

Pitt55

I don't know how much difference there is between std. and mag. I just go by the manual. I have done some testing between CCI and Win. and found I got higher velocities using Win. Not much but on average about 50 ft/sec. Maybe a guy should do some testing on the std. versus Mag. as well. Have to wait for spring for that tho.
Don

Grumulkin

Believe it or not, NO ONE goes by the manual even if they're deluded and think they do.

Handloading manuals have data from pressure barrels for some data and for individual firearms for other data. Even if you use the same components listed, you gun will be different, your powder will have a different lot number as will your primers, etc. This means that in every case, you must either go with a conservative load from the manual or work up prudently evaluating for pressure signs. If you're one who works up prudently and know how to evaluate pressure signs, you can switch things like primers, cases and bulletes safely.

Now, if you're going to start a bonfire, will it make it much bigger if you start it with a hotter flame? Not really. Likewise, a primer is used to start a fire and doesn't have a lot of explosive material to add to the fire it starts. In medium to large sized rifle cases where the load isn't on the ragged edge of overpressure, you can interchange various primer types without a problem. I've done it many times.

In all times I've interchanged primers, in only two cartridge/primer combos was any adjustment in powder needed. One was when I tried CCI 250 large rifle magnum primers in 44 Remington Magnum loads with H110/Win. 296; in that instance I had to reduce the load by 1 to 1.5 grains. Another was in a rifle (257 Weatherby Magnum if my memory serves me well) in which Remington primers required about 1.5 grains more powder to equal performance obtained with other primers.

In some cases accuracy will improve with a magnum primer even in cartridges not called magnum. My 357 Herrett does significantly better with CCI 250 primers than with other primers I've tried. A bit over a year ago, there was an article in Handload Magazine in which the author did testing in a 308 Winchester using various components and testing for accuracy with Varget. Guess what? CCI 250 primers gave him the best accuracy. Of course, magnum primers probably degrade accuracy at least as often as they improve it.

slimjim

I use standard rifle primers. While shooting minimum loads in my 45-70 using H4895 and Varget, I notice that not all the Varget burns and there are powder granuals left in the barrel when I push a the cleaning rod through it. The Varget does not kick as much as the 4895 so I'd like to keep shooting the Varget. I was thinking a magnum primer might allow all the Varget to burn.

Grumulkin

The reason not all the powder is burning and your gun doesn't kick as much with Varget is because the pressure is low. I don't know what kind of gun you're shooting. If it's a strong action like the Ruger #1 or Encore, you could increase the load a bit and solve your problem irrespective of which primers you use. If it's a weaker action, depending on which one, it might be best to leave the load where it is.

jimmybirdwell · Rookie Member Joined: Jan 29, 2010 Posts: 4

Thanks folks, very informative. I have a N.E.F. 243 bull barrel that I resently just got to shoot 1" at 100yards and that is with 65 grain v max. bullets. I really like 100 grain bullets but the rifle just don't like them. I have had this rifle abou 4 years and have giving up on it twice. I may try a 10% reduced load and mag. primers and see what it does. I will also work on my 65 grain load to tighten up the group. Thanks again for the help and comments. Again this is a very good site and I hope to veiw it often and maybe help someone else with their questions.
Jim

jimmybirdwell · Rookie Member Joined: Jan 29, 2010 Posts: 4

Thanks folks, very informative. I have a N.E.F. 243 bull barrel that I resently just got to shoot 1" at 100yards and that is with 65 grain v max. bullets. I really like 100 grain bullets but the rifle just don't like them. I have had this rifle abou 4 years and have giving up on it twice. I may try a 10% reduced load and mag. primers and see what it does. I will also work on my 65 grain load to tighten up the group. Thanks again for the help and comments. Again this is a very good site and I hope to veiw it often and maybe help someone else with their questions.
Jim

wiersy111

I have used magnum primers in all my large rifle load and can't sat that there is any noticeable change in accuracy. Any changes could be chalked up to the shooter having a bad day.

slimjim

jimmybirdwell wrote:

I have a N.E.F. 243 bull barrel that I resently just got to shoot 1" at 100yards and that is with 65 grain v max. bullets. I really like 100 grain bullets but the rifle just don't like them.

Jim, I tried to look up the barrel twist on your NEF but there is no data on their website. Call them direct at (866) 776-9292 and ask them what the twist rate is on your specific rifle. Then PM me or post it and I'll check to see if your twist rate might favor a particular bullet length (which relates to weight).

Vince

Welcome aboard Jim...I see Bushy has organised a beer for you mate.

I have always been led to believe that the difference between a standard primer and a magnum primer can add up to roughly 1 extra grain of powder in the load.

I first saw the difference between the two primers when a mate used to play with the plastic indoor pistol cartridges that used a primer to propel the "bullet". Standard primers resulted in an inconsistent "group" and magnum primers put homes in his refrigerator door. Embarassed

Cheers, Vince