L/R Primer vs L/R Mag Primer

[Deton8tor]

I have always heard that a magnum primer would create too much pressure in some cases as opposed to a standard L/R primer. Can someone advise if this will reach too much pressure in a standard caliber max or close to max load , 308, 260 ,7-08 etc?

 

[coyoteklr]

that is pretty much a loaded question..... kinda of apples and oranges
most of the loads even at max that are published have a cya factor....however it is a good idea that you load at lower than max and work up even if you use mag primers..... it is still the persons responsibility to do the work of experimenting to find the best load..... someone can give you a load, but it may be too hot for your gun... different barrel lengths...etc,etc,.....imho
i use mag primers on ball powders for better ignition which is my opinion..... and i don't use mag primers with ball powders in small cases....ie. .223... don't think it is needed, and that is my opinion.....
i have seen on other forums that the thing to do is lower your load by 2 grains and use mag primers ..... that sounds like a shotgun approach to me and not necessarily very safe approach.....imo

 

[357Mag]

EOD -

Howdy !

Federal's introduction of LR Magnum Match primers ( some years ago ), was the greatest thing since sliced bread ( IMHO ).

In my larger-capacity .224" cal wildcat, I was able to shoot the same throw weight of powder and not ( excessivey ) spike load pressure; while shrinking groups.
I was shooting WW760 under Hornady 55SX.

Same case shooting 40.5gr AA3100 in a 28" 1-8 SS barrel, I did not see pressure spike with change of primer between LR Magnun Match; and regular LR.
*** I DID see load vel drop 80fps when I subbed-in use of straight LR Match
primer VS the Magnum Match. ***
At the same time, groups shrank very nicely just from the change in primers.

In my more recent 6mm wildcat, shooting RL-22 under various 95 -105gr 6mm VLDs; I have been able to tweak load via primer switch. Again... I myself did not see an obvious pressure spike resulting from introdution of LR Mag primers to the load.

Having said that....... those results were in MY guns; shooting MY loads.
Fast burn rate powders might be a whole differ'nt critter... all-together ?!

The safe thing to do, would be to back-off the powder charge a bit when switching primers ( esp to use of Magnum primers ), and work your way back up to the sweet spot. That would not take all that many rounds to accomplish; and you'd have no unpleasant suprises.

Best of luck in your endeavors !

Regards,
357Mag

 

[Larryh128]

I use both & normally will initially drop 1/2 gr on a mag primer. I use mag primers on all ball powder, even the little stuff. I am sure that they will slightly increase pressure but not anything that I've seen that would take a safe load to excessive, unless you were already there. I interchange both in hunting loads when I'm in sub-zero conditions & don't see a difference in pressure & I really don't think you will unless you have a strain guage attached. Drop a little & work back up.