Due to availability I have been using small pistol, small pistol magnum and small rifle primers interchangeably in my .357 686 for my down loaded target/plinking loads. I have never seen any real difference either in accuracy or pressure signs.

The go to load for me is 5.2 grains True Blue with a 158g SWC in full length 357 brass which should produce in the 950 fps range.

By mistake I bought a small quantity small rifle magnum primers, CCI 450. From what I've been able to read, the only difference between SR and SRM is the thickness of the cup. Does anyone have thoughts on using the small rifle magnums for plinking loads.

To be clear, when loading full power 357's I use ONLY small pistol magnum primers.

IN A 686 NO PROBLEM.

As long as your revolver will reliably ignite them, I personally don't see a problem. Many competitive action pistol shooters have been using SRPs of various types in handguns for decades.

I’ve used Remington 7 1/2 small rifle magnum primers in my .357 loads with no problems.

Now a days, with the primer shortage.......
what ever "floats your boat" is how it is getting done, in these times.

If it fits in the hole..............
and goes "Bang", you are doing well, in the game of reloading.

Brand "Y" is a good thing, today if it can be found on a shelf !!

Thanks all, I appreciate the input.

Go for it. I have been loading LP Magnums in all My large pistol brass for decades. Including 45 ACP.

Actually, if you're using Winchester LPP they only have one flavor rated for both standard or magnum use. If it was unsafe they would never do that.

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Freedom is never free!!
SWCA #3437

I researched this a bunch. Most info says the only difference between SR and SP primers is SR are slightly harder to ignite.
My experiments are limited, but I loaded 50 ea .380 and 9mm using some very old Remington SR primers. I no difference noticed at all. They all went bang. The .380s went through my Ruger LCP. The 9mm's through my wife's M&P.

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Chris
SWCA #2243 SWHF #292

I've been using BR4s behind H110 for about a year and the light the prettiest fireball I've ever seen, with no signs of over pressure...

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This is the way....

Other than maybe a harder primer cup, SR and SRM primers should be just fine for reloading 357 Magnum cases. If you want to be really cautious, as I am, and if you are at or near a maximum safe load, back off the powder charge a few tenths of a grain and work up.

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VCDL, GOA, NRA

You don't really need SRM primers as normal SR primers will provide all the pressure safety you need. I have always used ordinary SR primers in all sorts of handgun loads, even 9x23 Win loads which generate chamber pressures in the 50Kpsi range, without any failures. Of course if you feel safer using SRM primers, there is no reason not to use them if they fire with 100% reliably in whatever guns you are using them in.

Humm I was taught from our engineering people that Mag primers not specific to that ctg causes different pressure curves dependent on Powder as in Over pressure...then again what do they know they are just the Chem Engineer Folks at NOS Indian Head when I worked in the Metrology lab... some of our folks came from major powder manufactures. Im thinking the advice above is Reckless. BTW the difference in SR and Mag SR or LR and Mag LR etc has little to do with Primer Anvil or "Hard or soft" Its the Primer Base Chemicals which can and will change the Weapons barrel pressure. WA Y WAY to much bad info. I would add a Disclaimer on ANY reloading info given here to keep the site from Suite when someone hurts themself with bad advice.

That's why I said I was cautious, especially if the current load is at or near maximum safe. Back off the charge a little and work up. I'd say the same advice goes for just switching primer brands.

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VCDL, GOA, NRA

Hmmmm? With all these dire warnings about getting hurt by switching primers in handloads???. Getting hurt, really?? I wonder why primer mfgs state that the only difference in SR and SPMPs is cup hardness. I would like to see REAL evidence where switching primers in any handload sent pressure spiraling to catastrophic levels causing injury from a blowup.

We most likely won't.

Any 'blowups' we hear about are most likely be due to OTHER reloading mistakes or negligence and not due to something as simple as substituting primers.

This is an old, and often repeated thread on most gun related forums and will probably never be 'put to rest'.

Well to the post above from the gent in Indy I would ask... Sir Can you tell me the Compound mixture ( In stoichiometry Terms ) for SP and SPM or any other Sir....you are quite wrong in your advice.... Hard or Soft Primers has to do with Anvil thickness and primer material. Expelling gas with false info gets people dead. Oh BTW I have seen first hand reloaders that over charge, or use the wrong powders and primers several times and Applied a Tourniquet to the left hand that had 3 fingers blown off from a gent and his M1a in 2004 ...Im a RN and Combat medic, a Engineer in Aerospace and Materials.BTW spent 3 years Indian Head MD NOS and 2 years Beretta 1985-7 setting up the M9 Line. USE POWDER AND PRIMER MANUFACTURE INFO ONLY TO RE-LOAD.

I've been using SR and SP primers as being virtually interchangeable for years, long before the current shortage. As a former sponsored competitive shooter for Hornady, I had a ton of insider info available. Of course it varies by brand, but for the most part standard small pistol, and small pistol magnum, and small rifle standard and magnum are pretty much the same thing. I've used whatever of whichever one was available with absolutely no perceptible differences for years. Only caveat is that CCI small pistol seem to have pretty hard cups, and I've had some misfires in my 5 screw K38, with it's light hammer spring, and amazing trigger pull.

No I am not knowledgeable as to the specific chemistry of primers. But we are talking about primers not blasting caps that are going to detonate a powder charge and blow up a gun. I want to see real evidence of a blown up gun loaded with any full charge load in the .357 magnum at even top pressure of 35,000 psi that blew up from the ONE variable of ANY primer that could fit in the case other than the specified being used. With this kind of nonsense being bandied about today it’s no wonder that their are so many handloaders that are scared to load anything but squibs. Most quality guns today have a 100% minimum safety factor as to excessive pressure. So let’s see ONE REAL case of lost fingers caused by primer substitution. Just ONE !

Ive got 2000 Remington 6 1/2 primers Ive been using in lieu of small pistol magnum primers. Ive seen no change in accuracy of loads, or any pressure signs. Actually, seems like the loads are bit cleaner and the brass just falls out of the chamber.

Well over 20 years ago, I did some very extensive testing of SP vs. SR primers (CCI) in numerous .38 Special loads through a Model 14. To boil down a lot of data into one sentence, it seemed to make no significant difference in MV or grouping regarding which primer type was used. That may not be the case for all calibers and loadings, but, as above, I treat SR and SP primers as being identical in ballistic performance. The main consideration is if the gun's firing pin impact energy is adequate to produce reliable primer ignition. But I do not use SP primers in rifle calibers, as the likelihood of a high-pressure blowout would be increased.

Does it not seem logical that if it was hazardous in any way to use SR primers in pistol calibers that the primer manufacturers would, at the very least, post a warning notice to that effect on the primer box? I have never seen any such notices.

In order to stretch out my lpp supply I cut out some 26 gauge shims on my mini mill to allow me to use the spp pocket thin rim .455 Webley brass that I’ve got. Use these in .45colt Ruger Vaqueros. I’ve swapped my last 2 bricks of spp for lpp so now I’m using srp for all my small primer needs. I did have to replace my weak hammer springs. I had lightened them years ago as I shoot duelist but the heavier ones are no problem. I also bought a 45acp Blackhawk cylinder and fit it to my birdshead vaquero to use .45acp small primer brass.

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Bought 500# fully reprocessed 45acp small primer brass WITH PRIMERS back in 2018...

$35.00! SHIPPED!

Those were my 1st experience with small primers in that caliber. No difference I could discern from other cases usingLPs.

Bought 500# small primer 45acp brass in 2020: these were not primed, but they were 98% Speer +P in nickel and appeared (to me) to be once fired. About the same price.

I'm good re: brass in that caliber, but I wish more SP primers were readily available...

Loaded up a couple hundred using SRPs (from cci) and no problems.

Cheers!

Over the years I rarely loaded .357's. I'm generally a .38 Special guy.

In the last couple of years I decided that I need to take advantage of the previously unused performance. Since I never had much call for SPM primers I've not thought to keep many on hand.

I've been using mostly Remington 6 1/2 SR primers in combination with H110 and other ball type fueled .357 mag for a while now. In my limited experiences I've found little if any difference in performance, none in reliability between SR and the older CCI 550 SPM I have on hand.

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GOA
USA Shooting Supporter

Correct me if I'm wrong but I thought the OP's question pertained to " Small Rifle MAGNUM " primers . Not just std SR primers . Regards Paul

As I said, there is no particular need to use SRM primers, but there will be no difference in their performance vs ordinary SP or SR primers if they are used in handgun calibers.

As said above there really is no difference in SR and SRM primers when used in handgun loads. In my chronograph tests of different primers with loads using 2400 powder in the .357 magnum I compared Federal 200 SR, CCI 400 SR and Rem 7 1/2 SRM primers to Win SPM primers. With the same charge of 2400 the Win SPM primers gave higher velocity than any of the three rifle primers.

PLEASE SEE INFO FOR PRIMER USAGE FROM POWDER MANUFACTURE.




HANDGUN LOAD SAFETY
Handloading Precautions

Most pistols and revolvers function best when loaded with a quick-burning powder such as Bullseye. Since peak pressure is reached very quickly, the SEATING DEPTH of the bullet is very important; the deeper the bullet, the higher the pressure. If the bullet is seated too deeply, dangerous pressures will be generated, which could burst the gun and cause severe personal injury (including death).

Equally critical is the powder charge. Guard AGAINST multiple charges when reloading. Certain cartridges (notably .38 Special) have been reloaded accidentally with double and even triple charges, with catastrophic results when fired in the gun.

A. Prevent deeply seated bullets.

Your assembled cartridges must be as long as, or longer than, the minimum length listed for the combination you are reloading.
Set your bullet station accordingly and lock tool securely.
Keep bullet station clean of accumulating lead and grease.
Inspect all loaded rounds for overall length.
Be sure every bullet is held tightly by shell mouth, especially pistol loads (recoil drives magazine against bullet noses of contained cartridges).
B. Prevent multiple charges.

Handloading: Keep track of every powder charge, then look inside all shells and compare powder levels.
Progressive reloading: Be sure every shell is truly empty; don't back up the turret; don't jiggle the handle; don't use a shell to clean out the powder train (use a paper cup or equivalent).
C. Inspection.

Discard cases with split mouths.
Discard cases with enlarged primer pockets.
Do not use cases that are designed for primer-propelled practice cartridges;
such cases may not be designed for full power loads.
Physical Effect of Gun Recoil (Kick)

The rearward motion of every gun, its recoil, increases when heavier shot or heavier bullets are fired, and when higher velocity loads are fired. This motion must be opposed by the shoulder, or the pistol hand, of the shooter. Whenever the recoil is perceptibly annoying to the shooter, accuracy on succeeding firings, undoubtedly diminishes.

When the shooting condition demands heavy loads and high velocity, recoil kick can be reduced by using a heavier gun, and by spreading the force over a larger area of the anatomy, such as by using a wider stock, larger grip, plus shoulder pad or softer grip.

Excellent publications available to the reloader, plus his or her own grown sophistication, have generated a wholesome trend away from maximum loads and toward accuracy of loads no more powerful than needed to accomplish the particular shot. Reducing recoil increases accuracy.

Contributing to increased accuracy as well as the pleasantness of shooting is in two main areas:

This Reloaders' Guide includes many reduced loads.
Our research indicates that the burning rate of powders has a modest effect on recoil.
For example, whenever two or more powders are listed for the same load, the slower one usually is chosen by the expert shooter as giving milder felt recoil. An intriguing aspect of reloading at home is the freedom to assemble, for example, trap loads with Red Dot or Green Dot powder, then to shoot them alternately to decide which seems more comfortable.

Additional Handloading Precautions

Understand what you are doing and why. Read handbooks and manuals on reloading. Talk to experienced reloaders. Write or call suppliers of components if you have questions or are in doubt.
Stay alert when reloading. Do not reload when distracted.
Establish a loading procedure and follow it. Do not vary your sequence of operations.
Examine empty cases (shotshell or metallic) be sure they are in good condition before reloading. Never force live cartridges into or out of the chamber of a gun.
Do not use cases that are designed for primer-propelled practice cartridges; such cases may not be designed for full power loads.
Do not ream out or enlarge flash holes of metallic cartridge cases. This may change the ignition rate and result in dangerous pressures.
Do not punch out live primers. Fire the empty primed shells in a gun.
Do not mix primers. Primers differ in brisance of ignition, which affects pressure and velocity. Use only the primer listed.
The shotshell loading data in the Reloaders' Guide are for LEAD SHOT only. Do Not use steel shot.
One-piece plastic wads for shotshells vary compressibility and gas-sealing effectiveness. Use only the wad listed.
If you "throw," or measure powder charges by volume, check-weigh the charge frequently. Do not mix powders.
Do not use powders near a flame, spark-producing machinery, or heating device. Do not expose powders to temperatures above 100ºF.
Keep out of reach of children.
Do not smoke while reloading.
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OH NO. The “astute” Mrnurse is bacccck ack.

And don't forget to wear your mask at all times...?

Especially when in front of the cameras!

Cheers!