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Magnum Primers for 5.56/.223

9K views 19 replies 11 participants last post by  68c15 
#1 ·
Doing inventory tonight and I have a about 3k-what powders require magnum primers for this caliber?
 
#2 ·
A quick look in the Hornady manual doesn't show any powder needing magnum primers, at least as far as I can see.

As an aside, the 300 blackout, which uses a cut off .223 case needs magnum primer with all powders. Go figure!!

I have 10,000 SR magnum primers!!
 
#4 ·
I just spent a few minutes looking at the load data in the Lyman #49 manual. It doesn't have any data calling for magnum primers either. We have a member who I haven't seen in a while (JLA) who said that he always used magnum primers in his .223 loads and his posts convinced me to do the same. That is why I ordered two cases of them. When my regular SR primers run out, I am going to start using nothing but Magnums.
 
#6 ·
The CCI 41 is a magnum primer with a thicker cup. The mags give about 50fps more velocity than standards when clocked. In my AR-15 Varget & BLC-2 work fine with standard primers although Hornady 9th manual just says "Winchester" for the primer under 556. For the CCI 41 I drop the charge down a few tenths or else the SD goes up.
 
#9 ·
I prefer to use magnum primers for any spherical powder. Some manuals call for em and some don't.
From my experience, I know that the ball powders are harder to ignite than extruded/stick powders in every caliber I've loaded...especially in the cold winter weather that I get. I try to use magnum primers with those powders whenever possible.


As for velocity difference between standard and magnum...I've never chrony'd any of my .223 loads with both primers to see if there is a difference. There may be.
In the .204Ruger, there is neglible difference. I get more velocity deviation from powder charge weight deviation than I do by switching mag vs std primers.

Long story short, use starting loads and work up with whatever primer you choose.
 
#10 ·
As a rule ball powders use magnum primers, like H335, BL C2, Win748 and probably a couple others as well. Ball powders had a reputation of being difficult to ignite when the temps are cold, and could produce a hang fire or a squib. The other side of that coin is max loads developed and used in cold weather can produce dangerous pressures when used in hot weather. For whatever it may be worth, I use Remington 7 1/2 primers for most all of my .223 loads. Some data lists them as a benchrest primer, some call it a magnum primer.
 
#13 ·
You know, I've never had a hang-fire or squib load with ball powders all the way down to -30°F. I do see a rather large velocity drop off at those cold temps with most loads though. Some only 100fps, but some are up to 250fps different. No, it isn't fun trying to chrony loads below zero, I was just running loads out of curiosity. My load dev is done during much warmer temps...at least 0. :)
 
#16 ·
I think Bindernut is on the right path here. Handloader just had an article covering primers and they stated ball powders (having more surface area) generally require magnum primers.

In my 6.8 loads I am using #41 primers. I've tested for accuracy deviation with #41's, BR4's, 400's and 450's and have not seen a difference out to 200 yards. This is all with ball powder (2200 and H322)

In my 223 loads I use IMR3031 and either 400's or Wolfe primers
 
#17 ·
I've tested standard and magnum primers using CFE223 with bullet weights from 40gr to 69gr. There might be a slight improvement in accuracy with the 69gr bullets using magnum primers, but it is very small. With bullets of 40gr to 64gr I could not see any difference.
 
#18 ·
Magnum primers for Ball/Spherical has been the general rule for a lot of us. I've been loading since the '70s but along with time comes development in powder the mag primer rule doesn't apply to some newer powders. In this Wiki article some info is pointing to that. Also it's not ball powder surface area but the coatings that make it difficult to ignite.

http://en.wikipedia.org/wiki/Ball_propellant
 
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