Remington Magnum Primers

[DrMLap]

What's wrong with this photo? Do you see it?
Cartridge_litestrike_crpd.jpg
This 357 Magnum cartridge is a reload using Remington 5-½ primers. The 5-½ is a small pistol primer, but so is the Remington 1-½. I have read that the 5-½ is a magnum primer while the 1-½ is not. So what's the difference? I have also read that Remington's 5-½ has a thicker metal case than the 1-½. That would explain why I couldn't get this cartridge to fire after at least five tries, even though my S&W model 327 TRR8 has an extra long firing pin from Cylinder & Slide.
To be fair, my S&W has also had a trigger job that brings my trigger pull down close to 1 lb. To do this, my gunsmith replaced the hammer spring. I suspect that spring is a lighter one, which means the hammer strikes the firing pin with a little less energy. Experts reading this can verify if that is true or not for trigger jobs.
So why am I using Remington 5-½ primers? Because at the time, that was all I could get. It was that or nothing, so I took it. Now I am paying for that with multiple light strikes from these loads. But that's OK because I'm just using these for target practice. My loads that I am saving for serious shooting—IYKWIM—are using Federal #100 primers (and Hornady FP/XTP bullets). And I have NEVER had a light strike from my Federal primers. I have stopped using CCI #500 for that very reason.
So, my question to all who are reading this, is: Do most magnum primers have thicker cases? Or is this just a Remington thing? What is the difference between a magnum primer and a non-magnum primer anyway? Why would I ever want to use a magnum primer?

[Unclenick]

That's a light strike on the marginal side. If the revolver had its spring lightened for easier double-action shooting, that will do it. I did the same thing with a Wolff spring kit for my Dan Wesson 357 long ago. Stopped it from shooting reliably. Federal primers solved that, as they do seem to be more sensitive.

[DrMLap]

Yeah, that's why I use Federal primers (when I can get them ).
But I still want to know why I would use magnum small pistol primers.

[Unclenick]

Magnum primers make a bit more gas than a standard primer does. The idea is a "magnum" case, as its name implies, is larger than standard, and therefore it will take more gas to pressurize it adequately to achieve consistent ignition and not get delayed ignition or squib out. The delayed ignition is the tricky one, as the delay is often shorter than we can sense (a few milliseconds or tens of milliseconds), but, its effect is like having your lock time vary with each shot. The added delay lets the muzzle move around more and tends to work against accuracy for that reason. You need really consistent follow-through to shoot a gun that's doing that.

That said, obviously, the "magnum" label isn't always indicative of the need for a magnum primer. I would not bother with one in a 32 H&R Magnum because the case is still very small, despite the title. That's a situation where the magnum might make things worse by starting the bullet out before the powder burn gets underway.

The simple way to check is to shoot some rounds over a chronograph and look at the velocity standard deviation. The primer that achieves the lower standard deviation is the one producing lower overall ignition variation.

[44 AMP]

Something very odd looking about the primer shown. It may just be a trick of the light, any way you can show us the primer from a different angle??

[Unclenick]

If you mean the dark patches, I assumed that was a reflection. But it wouldn't hurt to see it from a different angle.

[DrMLap]

Sorry, that cartridge has already been disassembled. I'm sure what you're seeing is "just...a trick of the light."
You know how a fired primer looks when you've loaded too hot? That's a little bit like what my Federal #100's look like after firing a medium load. That, I assume, is because Federal #100's have a thinner cup. These Remington 5-½'s never look that way—the one's that actually ignite, that is.

[Aguila Blanca]

Originally Posted by DrMLap

To be fair, my S&W has also had a trigger job that brings my trigger pull down close to 1 lb. To do this, my gunsmith replaced the hammer spring. I suspect that spring is a lighter one, which means the hammer strikes the firing pin with a little less energy. Experts reading this can verify if that is true or not for trigger jobs.

Whether or not a "trigger job" involves replacing the hammer spring depends on the gun, the gunsmith, and the desired end result. Often, a marginal or even a rather poor trigger can be cleaned up by stoning and polishing mating surfaces and without replacing springs. However, you said you now have a 1-pound trigger. My guess is that this almost certainly involved a lighter hammer spring, and probably not just "a little" lighter.

Are you a bullseye shooter? Do you need a 1-pound trigger? If not, you might consider replacing the hammer spring. I haven't checked for your specific model but for most guns Wolff sells tuning kits that typically include four to six different hammer springs of various weights, allowing you (or the gunsmith) to find the lightest spring that still provides consistent ignition.

[Unclenick]

In large primers, cups are pretty similar because a thickness adequate for a wide range of pressures indents more easily with the wider diameter, so they don't need to fuss with it much. With small primers, cups have a range of thicknesses. Federal actually added to that by making its GM205MAR primer meet military sensitivity specs through thickening the cup.

[44 AMP]

perhaps just a trick of the light but that primer SEEMS to be both a light strike and cratered.

Now, a high pressure load can sometimes push the firing pin strike back out, making it appear to be a light hit. Though when this happens it usually also noticeably flattens the primer and that doesn't appear to be the case here.

An overlong firing pin can also result in a cratered primer, even at normal pressures, as can the fit between the firing pin and the hole it passes through.
of course if I'm just seeing a trick of the light, then the above is moot...

model 327 TRR8 has an extra long firing pin from Cylinder & Slide.

SO, you've got a extra long firing pin and light springs and one brand of primers doesn't work reliably...hmmm

I would point out one thing about language, you don't get light strikes from the primer, you get light strikes from the gun.

I would shoot some of that ammo from a stock, unmodified gun and see if it fires reliably. If it does, and it should, then I'd say those primers are unsuitable for your customized, modified gun.

That doesn't mean the primers are bad, or that your gun is bad, it just means they aren't suited for each other.