Do we still need both large and small primers?

greyling22 said:

I know that many of the cartriges we load today were designed nearly 100 years ago, and times and technologies have changed since then. We are seeing 45 acp and even 45-70 loaded with small primers now. Is there any reason, other than tradition, that we still have large primers? it seems like a lot of extra work for everybody to have 2 sizes of primer if we don't. Taking it even further, I wonder if a small pistol magnum might work for nearly every application. (though I would be leery about guns with floating firing pins)

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Those are good questions, and shows just how little information is available to the shooting community on primers and primer characteristics. I believe it all comes down to the available energy in the primer, which could be broken down into flame temperature, duration of primer combustion, and mass of hot prime cake ejected into the case to ignite the gunpowder charge. And then, ignition would have to be reliable for all powders, for all cases, in all temperatures.

This is one of the few bits of information on primer design that are in the public domain:

Percussion Primers, Design Requirements

But, without data, don't know if what you propose is feasible.

Do we still need both large and small primers?

Only if you need them and the data calls for them.
A lot of "extra work" ?? Do we need more than one caliber, powder or bullet size?

Are you asking for 1 primer to light everything from 25 ACP to 50 BMG??

Nope sorry, ain't gonna happen.

https://www.starlinebrass.com/308-match/

It's happening

I don't think we'll see large primers go completely away anytime soon. I recently purchased some Starline .460 S&W brass and it is just a lengthened .454 case, but instead of following the lead of using the small primer the .454 uses, they are all large primer seats. I suspect it is to optimize the ignition of the large volume of slow burning powders that case holds. The mutli-size scenario predates the metallic cartridge into the age of the percussion cap and to this day we have several sizes of caps for pistols and rifles.

Blakenzy said:

https://www.starlinebrass.com/308-match/

It's happening

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As with all types of cases this large with small primer pockets, it will require care in powder and primer selection in cooler temperatures to prevent hang fires. Single-based propellents are generally easier to ignite and a quality primer such as the Remington 7 1/2 BR are recommended.

There was a study on the effect of flash hole size on accuracy,
example- Dasher cartridge with a drilled out flash hole suffered in accuracy as the hole was enlarged .

Addendum- I’m trying to stay away from conjectural posts therefore the above is as far as I’ll go.

We need large pistol primers until me, my kids and my grandkids run out of all this brass that requires them......

I think this falls under " If it ain't broke don't fix it."

308 SP isn’t anything new. Lots of small BR stuff has been based on them for decades.



I don’t know if you need them but I’d have more than a few 5 gallon buckets of brass that would be useless and some firearms I could no longer use if there were no large primers any longer.

I suppose I could come up with a new product and sell “primer bushings” for all the other guys and gals that would be in the same boat....

In my way of thinking if there was no need for all the variations of primers the manufacturers would stop making them as a cost savings measure. Kind of like the obsolete brass. Cup thickness is also a variable. I use SR primers for most of my small primer uses. I reserve SP primers for handguns with weak firing pin springs that will not reliably ignite the SRP and striker fired handguns. As long as LPP brass is made and used then I will stock them as LRP are a different depth and will not work. In my 500 S&W MAG some casings use LPP and some use LRP (marked LR). All the new brass is marked LR.
Sometimes something old is something new again like those 308 brass.

If they just had Phasers then there would be no need to have calibers or reload anything! But then it would be like Glocks and have "generational" models!

I recently made the switch from .308 Win LR primers to .308 Palma SR primers. Primary reason was to get better brass life when running competition loads for F Class. I've read that ES and SD is better with SRP vs LRP when comparing .308 although I've yet to test it myself.

I think a more relevant question would be , do we really need pistol magnum primers?

If Winchester can make LPP primers for all uses why the heck not?

Then of course there are those "Match" primers which are supposed to be better and then there are the Black Rifle primers (41) which none of the load data call for and for decades no one used them as they were not "marketed"

if 454 Casull can get away with small rifle primers I'd guess anything smaller could make due with them. FWIW for .460 S&W they went to large rifle primers rather than large pistol. For .308 Win or smaller I'd think small primer would be adequate. For some of the Magnum rifle rounds I'd guess the larger primers will work much better.

Rule3 said:

I think a more relevant question would be , do we really need pistol magnum primers?

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Yes, if for no other reason than cup hardness. Some people need federal-soft primers for their soft-springed DA revolvers. Some people need CCI magnum-hard primers to keep hot loads from cratering in a gun with a loose firing pin hole in the breech.

ATLDave said:

Yes, if for no other reason than cup hardness. Some people need federal-soft primers for their soft-springed DA revolvers. Some people need CCI magnum-hard primers to keep hot loads from cratering in a gun with a loose firing pin hole in the breech.

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Amazing that Winchester can do it.

Rule3 said:

Amazing that Winchester can do it.

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Winchester can do it, but not all guns can do Winchester! For precisely the reason I gave above.

I've had Winchester LP primers fail where std CCI did not. Never had a failure when they were Ni plated. Also LRM is a different size.

This difference in primer cups is thickness not "hardness" Although thicker is construed to be "harder"