I started to reload a batch of 357 magnums today and then I noticed that in my Hornady 9th edition manual lists Winchester small pistol magnum (WSPM) primers for all their loads they've listed & then I go in my Speer #14 and it only lists magnum primers for some powders and not others.

I found two similar loads in both manuals using the same powder yet the Hornady manual states small pistol magnum and speer for the same load just uses standard primers. Again, in the Speer manual, some loads get the magnum primer and others don't meanwhile the Hornady book, all loads get the magnum primer...

I have a whole case of Winchester WSP primers, I'm just gonna use them... here's the load data I'm using today.

158 gr. LSWC HP

3.8 gr. TiteGroup

OAL 1.590"

I think in this case, I'm fine using standard primers.

Going by that reload data you posted, that isn't a magnum charge, so the small pistol primers would be what you should be using. When you start to get into the high charges of H-110 /win 296 than you need a small pistol magnum primer.

Magnum primers are used for slower, hard to ignite powders, aka "Magnum powders". The data in the manuals are just reports of what the lab techs used and the results, not hard and fast formula. Also components vary from lot to lot and one of the reasons reloading manuals differ in their data. Your load sounds fine.

I have used mostly standard primers in my Magnums with the exception of when I'm using H110/W296. I've also read some use magnum primers with 4277, but I haven't tried that powder...

Double base ball powders have more deterrent coatings than single base powders to help control the burn rate and lower peak flame temperature.

The deterrent coatings make the double base powders harder to light off and all the older manuals show the use of magnum primers.

Food for thought, Remington ran Lake City Army Ammunition Plant from 1941 until 1982. And they used the Remington 7 1/2 primer for all the 5.56 ammunition produced. They also loaded the 5.56 ammunition with Winchester ball powders.

Now look at the photos below of different type primers and pay attentiohttp://www.6mmbr.com/primerpix.htmln to the Remington 7 1/2 primer they used to light off Winchester double base ball powders.

Primer Flash Test Photos

I have posted this note before. SPEER RELOADING MANUAL #14, Caliber: 357 Magnum, page 892, Do not use magnum primers with 2400 or VihtaVuori N110 loads shown here or high pressure will result.

Your load using Titegroup is fine with regular primers.You'd be surprised at the number of guys who walk up to me and say they use magnum primers just because the word is stamped on the brass.
I usually take a few minutes to explain them that it is the type of powder and not what is stamped on the brass that is the gauge by which the use of mag primer is mandatory and for my part,I use Mag primers with such slow burners as H110/W296 and IMR 4227.There might be a few others but I don't use them.
Qc

I was going by the load data in my Hornady 9th edition reloading manual & comparing it to my Speer #14 book. The Hornady called for Magnum primers in all the loads whereas the Speer only listed magnum primers for certain powders. I thought that was interesting.

Although most loads I went by off the Hornady manual were very good, their loads seem to be more "conservative" when compared to the same loads listed in Speer's book.

I only use Mag primers when the load calls for a "Ball Powder"...........

Flake or extruded powders do well with a standard primer.

Since Winchester is a ball powder company, both their std and mag primers will work for all powders.

I use Small Rifle primers for about any load in any handgun cases having a small primer pocket. Works fine. Any regular SP primers will be OK for .357.

Handloader (the magazine) had an article awhile ago that magnum primers cause an increase in some powders (as noted above). It was an extensive article with a lot of data. Generally only a concern if loading towards the maximum.

I always use the non magnum primers in my 357 calibers. Never had a problem.

Well standard primers for that load is just fine. I load 3.4 in 38 special with that powder and a 158 grain SWC. As for H110 I've used standard CCI primers and loads and groups were fine. H110 in a .22K hornet with standard pistol primers groups better than rifle primers or mag primers. I've also used standard primers before in the 44 Mag as well. Now I know some may say not so but it works. During the primer shortage I was using Tula primer but my go to primers are CCI. Which by the way I have several thousand stored. And with this said and shooting and reloading since 1979 a lot of shooting has taken place.

I use the correct primer that’s required for that powder. For large pistol primers I use Winchester primers it covers standard and magnum primers.

In rifles there is three different large rifle primers. A standard primer, a military thicker wall primer 1 1/2 Times hotter over standard. Them the magnum primer is 3 Times hotter over standard. This means a hotter chamber pressure too. You must read the fired primer in the case too for higher pressure.

Pray tell, exactly where did you find this information? And what does "Hotter" mean?

"In rifles there is three different large rifle primers. A standard primer, a military thicker wall primer 1 1/2 Times hotter over standard. Them the magnum primer is 3 Times hotter over standard. This means a hotter chamber pressure too. You must read the fired primer in the case too for higher pressure."

Speer used to list magnum primers only for the powders that were hard to ignite, slow ball powders. Nowadays most "Magnum cartridges" will list a magnum pistol primer in the data.

I wrote Hodgdon a few years ago and asked them why they used a magnum primer with HP-38 in their .357 Magnum load data and was told they use a magnum primer with all their magnum load data. The reason, there are reloaders who don't pay good attention to the primer used and could assume if it's a magnum cartridge it must use a magnum primer. If they use a standard primer and the loader substitutes a magnum primer it could cause an over pressure problem.

I'm not sure if that's true but it's what they told me. I just figured they were being lazy and it was easier to use just one primer when testing all the powder/bullet combination in that cartridge.

__________________
Freedom is never free!!
SWCA #3437

Magnum does not mean you need a mag primer. I only use them for H100/W296 loads in my magnums. Everything else gets std primers, regardless of the book.

__________________
NRA Cert. Inst. IDPA CSO

You do not need a mag primer to ignite small charges of ball powder. All my 9/40 minor loads run fine on std primers. Going to a mag primer opened groups a bit with no appreciable gain in vel thus pressures.

__________________
NRA Cert. Inst. IDPA CSO

Fred;
This post was about the .357.

I did not mention 9mm or 40 in my post.

Well I will be working up some bowling pin loads shortly.
.357 mag 180 gr over 2400 and HS6, maybe something else if I have any partial cans laying around. Think I have some 4756 left over from my 38 super open days.
Anyway will use magnum and standard and see what the chrono says.

I only use magnum primers with W296/H110, HS-6/W540 and HS-7/W571 when I finds some. Everything else gets a standard primer. I won't know about W572 until I do some tests with both primers. The ES, SD and MV will decide which primer I will use.

__________________
Freedom is never free!!
SWCA #3437

I read an article last night, but I didn't mark it, daggum it. But the jist of it was that the lightest primer charge to effectively light the powder will give the smallest standard deviation. Though I use standard and magnum primers, I've always felt that a slight reduction in powder could level it. This info says that if narrow standard deviation is important to you, you shouldn't use a larger primer than specified for a load.

Being a recreational target shooter and not a competitor, SD doesn't affect me much, but if you are a competing shooter, you may want to look into this.

__________________
"He was kinda funny lookin'"

well if you guys really want to know. Although the recipe in my Hornady manual states magnum primers, I used standard WSP primers.

All my loads went bang & hit paper.

I shoot a lot and Chrono is a great. For those who have the money some out there just may not. There are those who go just by the book and then there are those who look at several books a leave scratching their heads. Work your loads up and go from there don't push over max and you start down a dangerous path. In 1935 a .357 mag load was 16.0 grains of 2400 with a small rifle primer. We all know reloading has changed over the years load data isn't list the same as the late 70's or early 80's for that matter.

Using my chrono, I found that mag primers in my 38S target loads reduced the standard deviation by 2/3rds over using regular primers. It showed on the paper with tighter groups at 25 yards.

__________________
40 yrs Millwright Machinist

Being a recreational target shooter and not a competitor with pistols or revolvers..........

I found over the years that some loads with a high ES, shoot better
than a lot of loads with a small ES spread.
Also some bullets shoot better at the low or high end of the FPS range.
Some with do all speeds but there is generally a "Sweet Spot" in a bullet/powder loading, at least with my weapons.

The chrony is nice but some times the answers are not what I wanted to see.
In the end I still just pick a load, no matter what the numbers.

I agree that velocity and pressure are measure more a accurately today. But the old loads seemed to work just fine and the only way to kablooey your gun was making some mistake, unless the gun was poorly made or defective, or if you plugged the barrel or shot a squib.

__________________
"He was kinda funny lookin'"

I use TiteGroup, I bought it believing Hodgdon’s claim that Titegroup powder was not sensitive to it position in the cartridge.
With std primers I was surprised at the wide velocity spreads I got in my 38 Spl.
The big flash of a Magnum primer tightened up the SD. I suspect the bigger flash more easily found and lit up the few granuals of of powder scattered in the big case. Rocking the revolver to position the powder to one end of the case helped lower the SD with std primers. The improvement in SD with rocking was less dramatic with the mag primers.

I have 2 lbs of W571 and don't know what loads to use for 357. Mild or wild?

I used to use small rifle primers with H4227 in .38 special but went to small pistol primers when it was discontinued and replaced with Mulwex AS2205. No issues at all despite this supposedly being "the same stuff".

The last batch of Winchester large pistol primers I bought were marked as being for "standard or magnum loads". Do Winchester still differentiate between standard and magnum with their SPP?

According to the Hodgdon loading site that is actually a .38 special loading not a .357 Magnum (4.5 - 5 gn with a 158 gn LHBWC) so standard primers are more appropriate.

higher chamber pressure.

Standard prime has less igniting spark over a military primer and a magnum primer. One must be aware when using near max loads with hotter primers.

I checked all my reloading books and each one is a tad different with the same load. I go by one book only spec wise.

I just use magnum primers in all 357 magnum and work my loads accordingly. Most 357 mag maximum loads are a shadow of their former selves.

With rifles the large rifle #34 nato primers, magnum rifle primers are higher power wise over the standard primers. I think the nato primers are equal to 1.5 grains of powder, were the magnum primers are equal to 3 grains of powder. My question is the pistol primers the same way?

__________________
Plant garlic in the fall

The reason the manual says spm is the slow powder data like h110. Plus the wsp primer has always been a tweener, inbetween mag & std primers, suitable for either use.

__________________
NRA Cert. Inst. IDPA CSO

Imo using a single data ref point is not the best approach.

__________________
NRA Cert. Inst. IDPA CSO

Since the magnum primers are all I have, no problems with my 38/357 loads.

Years ago my main shooting buddy and I went big in to magnum revolvers, and for a few years we loaded uncounted rounds of .357 and .44 magnum rounds. We used both magnum and standard primers and kept records of our results. Not surprisingly, the loads with magnum primers showed higher velocity than identical loads with standard primers -- but just as significantly the standard primer loads almost always gave more consistent velocities and better accuracy.

As a result, I haven't even seen a magnum pistol primer on my bench in maybe 15 years, and have never missed them. Of course, I also haven't seen one of my Lee Auto-Primes in a few months, so maybe I just need to clean off my bench and neaten up a bit... ;-)

__________________
Pisgah

Primers,primers,primers!Tough to bring a definite conclusion on them.Are they all the same?mag vs std,is this a hype?
I thought that the difference was about size only.In their small configuration,they are of the same dimensions.When you go to the large size,the height is a little different which means that when you use a large pistol primer(lpp)in a rifle case,it might seat too deeply(or not)for the firing pin to reach and detonate it.It is a ''try and see'' thing.
I also looked into the burning rates of primers;almost all tests reported that the small pistol primer was milder than the small rifle primer and same for lpp vs lrp.
In all cases,magnum primers burned hotter than their regular counterpart.So,what does this all mean?
Yes,you can use a regular primer with a powder that books recommend using a mag primer.it.ll probably give you satisfactory results.But it might also give you a plug of unburnt powder that gave just enough shuv to the bullet to become stuck in the barrel.This won't happen often.To me,just once and no,I didn't ''shoot another one to dislodge the stuck bullet''.Once is enough to get me thinking about it.
I tend to use hot magnum primers to make sure an easy to spark powder will ignite perfectly when it is cold(around and below freezing point)or when books say that such or such powder needs a mag primer.

Here’s an interesting test someone did:

Primer Testing Reference

Anyway, for my first hand load I will be using cci LRM primers in loading 0.50cal 400gr Sierras with H110 (2.05” OAL / 1.18” case space). For starters I’ll just take the average of all the published starting loads I’ve seen for this and just up to about 175 ft/sec slower than the average of max loads I’ve seen, since I’ll be using a 3.5”, not the standard tested 8”
Y’all think this will be a good plan?

Due to Covid 19......use what ever primers you HAVE.

Randy

Haha Yes, but sparingly