Question regarding mag pistol primers

[juggernault98]

So! I bought the wrong box of primers.. Thought I grabbed cci #500 pistol (or whatever) but I grabbed cci MAGNUM pistol primers. Needless to say I have to use them. I've never used magnums. So here is what I have currently:

Hitek coated (lead) 125 grn 9mm
4.8-5.0 grn unique
OAL: 1.080

Using the magnum primers how much powder should I cut? Should I start at 3.8 grns? I'm shooting for cost efficiency cheaper the better not really reloading for pin point accuracy (if it matters)

Thanks in advance.

[Fine Figure of a Man]

You could take them back and ask to swap for standard primers.
If you use them it would be wise to start at the minimum powder charge and work up.
They will have a harder cup which won't show pressure signs as soon. It's possible, but unlikely, that the harder cups will result in lite strikes.

[muleman11]

Does any pistol load really need a magnum primer? If not, why do they make them?

[Reloadron]

Using credible load data I would just start low and work up.

Ron

[Nick_C_S]

Does any pistol load really need a magnum primer?

Yes. They are essential for consistent ignition in some circumstances.

why do they make them?

Because some propellants - especially in large cases - are more difficult to achieve consistent ignition. HS-6 and W296 being excellent examples. BTW, magnum primers and magnum ammo cartridges are two different terms - one has nothing to do with the other.

Getting back to our OP: Yes, you can use your CCI 550's (and most places won't allow primers to be returned). But it would be wise to back down your charge by 10%, and work back up. 10% being 0.5 grains, in your case. This would be the cautious approach.

9mm is a small case and as such, small changes can translate into big differences in pressure. If you were talking 38 Special (a large case) and a target loading, I'd recommend just loading them with the 550's and moving on to the next dilemma. But you have 9mm; hence, the advice of caution.

A few years back, I did a bunch of workups for defense level 9mm ammo, using 550's. Most of the workups allowed me to get to published max - even with the more potent primers. But that is just anecdotal from your perspective. Do your due diligence.

[Reloadron]

Does any pistol load really need a magnum primer? If not, why do they make them?

The theory behind it is that ball and flake powders like Unique require more primer brisance. The priming compound in a magnum primer is formulated to produce a longer hotter flame to reliably ignite the powder charge. Magnum pistol primers are useful when loading large charges of slower burning powder (propellant) like Win 296 or H110. Loading 9mm with small light charges really doesn't warrant the use of a magnum primer but it likely won't hurt.

I see Nick already covered it.

Ron

[juggernault98]

Backing out 10% would be roughly 4.2-4.5. So I should be fine at 3.8 I'm not one to push the limits. So at 3.8 what would I be losing? Accuracy? Again I'm looking to shoot for fun not blow my hand off.


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[Nick_C_S]

So at 3.8 what would I be losing?

Velocity.

But to be more serious, if you wanna back down to 3.8, you probably should. That's where you're comfortable.

Accuracy at normal pistol distances would likely change little.

[jamaica]

Magnum primers are used in the 44 Magnum for certain powders. H 110, 296, and H-4227, powders call for magnum primers in my Lyman Manual.

In any case start light and work up a load. You can take a load from the 44 special specs to make some fun loads to play with. The old favorite of 6 gr of Unique would do it. Have fun!

[T. O'Heir]

"...any pistol load really need..." Depends entirely on the powder used.
Using a magnum primer might increase your pressures, but it will not cause any damage to anything.
4.8 - 5.8 grains of Unique is a jacketed bullet load, not for cast, coated or plated bullets. 4.8 isn't the right start load either. Alliant shows the Max load is 5.8 for a 124 grain bullet(one grain doesn't matter). 10% reduction is 5.2. That OAL is too short too. 1.169" works with any bullet weight. Been using that for eons with a cast 121 grain TC.
H110 usually does not require magnum primers.
"...will have a harder cup..." No they don't.

[juggernault98]

Originally Posted by T. O'Heir

"...any pistol load really need..." Depends entirely on the powder used.

Using a magnum primer might increase your pressures, but it will not cause any damage to anything.

4.8 - 5.8 grains of Unique is a jacketed bullet load, not for cast, coated or plated bullets. 4.8 isn't the right start load either. Alliant shows the Max load is 5.8 for a 124 grain bullet(one grain doesn't matter). 10% reduction is 5.2. That OAL is too short too. 1.169" works with any bullet weight. Been using that for eons with a cast 121 grain TC.

H110 usually does not require magnum primers.

"...will have a harder cup..." No they don't.

Okay good tips. I never worked with a 125 grn let alone cast. I reached out to the local manufacturer he recommended my oal to be reduced to around 1.080. It was around the time I first started out and I believe I was using a federal 115 grn round as a rough template. Obviously I have since learned the OAL differs from the weight and type of bullet used. Now do I have to worry about the burn off of the lead? Or whatever they call it where I get lead build up in my barrel?

[Chainsaw.]

I've heard.....take that for what it is, that mag pistol primers add about .01 to .02 grains of powder charge. So, if the starting load if 4.5 Id go say, 4.2. Mag primers are not dynamite, you'll survive. And keep in mind backing off to much can be bad news bears, usually its safe with pistol powders, notvso much with slow rifle powders, just fyi.

[reddog81]

Back off .1 or .2 grains. There's usually around a 10 to 20 FPS difference between the 2 primers. You will not notice any difference when shooting. Going down to 3.8 grains very likely could lead to the pistol not cycling.

[buck460XVR]

Originally Posted by muleman11

Does any pistol load really need a magnum primer? If not, why do they make them?

Some hard to ignite powders really do need them in cold weather in order to perform well. Some powders in in powder chargers perform better with magnum primers than standard primers and vice versa. Winchester only makes on large pistol primer for use in all loads. The real question would be, are standard primers needed if one can download powder charges when using magnum primers safely and easily? The answer is because folks have a preference, just like some powders and some guns.

[Stats Shooter]

Primers are not all made to the exact same specs by each company. CCI and federal for example have standard and magnum primers. Magnum Primers have a bigger flame/spark than standard for those two makers. Winchester doesn't make a magnum primer and it is well known that their standard primers are among the hottest of standard primers.

Magnum Primers were created to ignite certain ball powders that are difficult to ignite , or large volumes of powder consistently.

You can use magnum in lieu of standard, but you'll need to rework the load

[cw308]

I used the magnum primers in my 45ACP in a pinch , when ordering was a problem an backorders were the norm. I could see no difference , to be safe back off .1 of a grain . For that matter look at some flash holes , some are larger some smaller would also effect burn , also very little . If they don't take them back , get the standard primers an load 30 reg. 20 mag. Not a problem.