Primers/ Mag or Standard?

[pantannojack]

I get that slow ball types like 296/H110 need magnum primers and I had a Blue Dot load fail to ignite in a 44 mag lead load, the bullet lodged in the forcing cone. Load manuals can either specify one or the other or not at all. Beyond these examples, how can one determine what is best, or what is not good, for the loads we are making. I like to down load my magnum cases for everyday lead shooting in 357, 41, 44mg. I use 231, Red Dot, Unique, 4756, 800x, 2400, Hs7, H110.

 

[rockquarry]

I tried magnum and standard primers with 296 and #2400 in .357 and .44 Magnum and found a slight accuracy advantage using #296 and a magnum primer in a .357 load, fired from a 6" Python. One gun, one load, one standard and one magnum primer means nothing except more experimentation is needed. Try all the combinations you can and shoot enough bencrested groups to have truly meaningful information. I always go with what's most accurate.

One instance where a magnum primer might prove advantageous might be in very cold weather, but that's a guess on my part at this point. I've never done such testing and likely won't.

 

[alwslate]

I use magnum primers for all loads in the tall for diameter .357 case regardless of powder as do most reloading manuals. There is just no drawbacks to using magnum primers for all handgun loads period. Standard primers with reduced loads of 296 just for testing resulted in extremely poor loads in the .357 in my chronograph testing. 14 grs of 296 with a std priner chronographer at around 1050 fps with an extreme spread of well over 100 fps out of a 4" N frame with a 158 gr cast SWC. The same velocity can be obtained with less than 6 grs of Bullseye, 231 or Titegroup with way better consistancy. After comparing loads with 2400 with Std or Mag primers I will never use Std primers with it again. I just do not understand the fear some handloaders have of magnum primers. Cost is the same, availability might be better. What's the drawback?

 

[smithra_66]

I get that slow ball types like 296/H110 need magnum primers and I had a Blue Dot load fail to ignite in a 44 mag lead load, the bullet lodged in the forcing cone. Load manuals can either specify one or the other or not at all. Beyond these examples, how can one determine what is best, or what is not good, for the loads we are making. I like to down load my magnum cases for everyday lead shooting in 357, 41, 44mg. I use 231, Red Dot, Unique, 4756, 800x, 2400, Hs7, H110.

How can we determine? Get to the range and see what the gun shoots best, turn on the chronograph and see what gives the best standard deviations, etc.

Testing, testing, testing.

In my experience, the differences between magnum and standard primers in terms of shooting performance are almost imperceptible. MAYBE 10 fps more on the chronograph for mags?

I think a lot of the differences are in strength of the cup. I had a 6.5 Creedmoor load that caused standard small rifle primers to start to flow into the firing pin channel. When I switched to either "bench rest" or Magnum small rifle, that stopped. On the target and on the chronograph, there was no difference.

In 45-70 loads with 67 grains of black powder, standard works just fine...but so does magnum. Everyone says "you need magnum if you have more than 50 grains of powder, etc."

Not in my experience.

 

[stansdds]

Magnum primers are, in my opinion, absolutely necessary for the slow burning pistol powders. Powders like 2400, H-110/W-296, HS-6, and AA#9. With fast and medium burning powders, they are not necessary, but plenty of reloaders report slightly better powder combustion when using magnum primers with medium and fast burning rate powders. If given a choice of only one type of primer, I'd take magnum primers as they are a do-it-all deal, but I do not have any precision target revolvers or pistols that might not be able to ignite these primers.

 

[ArchAngelCD]

I have to agree about slow ball powders but with 2400 IMO a magnum primer is detrimental. 2400 just performs better with a standard pistol primer. Slow ball powders like W296/H110 and HS-6 show lower ES and SD numbers with a magnum primer.

As for AA#9, I'm not sure but if I were to use a lot of it I would test with both types of primers.

 

[chief38]

When it comes to reloading I usually "follow the rules" set by the manufacturers & reloading manuals. That said, once when I ran out of Magnum primers a few years back, I did use standard SPP's for .357 Magnum loads. They all worked just fine however there was a slightly lower average velocity (about 35-50 fps drop) as measured by my chronograph. There were only Range rounds and not loaded up to maximum pressure & velocities anyway so I did not really care.

I did restock my magnum primer inventory and now use the proper ones again. I have read about using other than suggested primers for a specific loading and the reports and posts I've read do state that they mostly work fine. That said, there obviously has to be some differences and so I usually try and stick with the recommended primers.

 

[twodog max]

I have burned a lot of Blue Dot over the years and never used a magnum primer and never had any ignition issues. Alliant does not use magnum primers with Blue Dot or 2400. I tend to follow their lead. I have used both powders in 357, 44 magnum and 45 Colt. No issues of any kind. If you had a problem with the blue dot I think there was another factor at play other than the standard magnum primer debate.
If you want to use magnums for everything well just go for it. It is extra expense, or at least used to be, just don't expect me to buy into it as a necessity.

 

[243winxb]

WLP or SPM. covers it for me.

 

[richrd]

Ken Waters did an in depth test of this issue in an old Handloader issue in which he test for velocity, pressure, and accuracy. He found few cases where mag primers were better.

He tested in .357, .41, and .44