At some point I’m gonna load .357. I use HP38 for everything, including .38 special. Primers are hard to find right now. If I can’t find small pistol magnum primers, can regular ones do in a pinch?

For lighting HP38 in a 357 magnum, small pistol primers will work fine.

Primers go with the powder used not the caliber.


Hodgdon used mag primers for anything labeled magnum for constancy only (per them many years ago)

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Still Running Against the Wind

So no using them if I can’t get magnum ones? I’ll be on the hunt for the magnum just wanna know.

Use what you already have.....

Randy

No. Whether to use magnum pistol primers or regular pistol primers depends on the powder you're using, not on the round you're loading for.

For example, HS-6 in .357 Mag should use magnum primers. Unique in .357 Mag will work just fine with regular primers. Will regular primers ignite the HS-6? Yes. Will magnum primers ignite Unique? Yes. But the magnum primers don't give you any benefit with Unique. With the HS-6 the powder burns more consistently and more completely with the hotter primer, so you get more consistent accuracy.

I've never used HP-38, but if I recall correctly it isn't a "hard to light" powder, so you probably don't need magnum primers for it.

For plinking, use whatever you have.

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I’m your Boogie Man, uh huh.

Use what you have you do not need Mag primers for that powder

Regular primers are fine with HP 38 and lots of other powders. It's all I use. I use regular primers for 2400 powder, Longshot and several other "slower" powders you do not need Mag primers for most of the faster or medium powders,

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Still Running Against the Wind

Thanks, Oh Wise One! 7 years later and still helping me out!

You can use regular or magnum or even rifle primers. Just make sure to build up your load again (especially if it’s near max) because you are changing components.

For HP-38 you will find that regular small pistol primers work just fine. In a pinch, you can also substitute small rifle primers for small magnum pistol primers.

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Only a cold warrior

You pnly need a magnum primer for 1 or 2 powders, the rest can be loaded quite fine with std primers.

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NRA Cert. Inst. IDPA CSO

Generally speaking, high density loads of slower burning powders may benefit from the additional output of magnum primers, but those uses are a pretty narrow slice of the usual uses. Standard primers are more than adequate for the majority of needs. As others have pointed out, when changing the primers in a load you need to start over again to work the load up for the primers to be used. DO NOT ASSUME THAT ANY PART OF THE LOADING RECIPE CAN BE CHANGED WITHOUT CAREFULLY WORKING UP THE NEW LOAD FROM SCRATCH.

I have come to the conclusion that all the small primers are interchangeable as long as your not pushing for max loads. Large rifle primers are not interchangeable.

When I was shooting 38 super major loads in USPSA years ago I used 540/HS6 and small pistol primers. I never had an issue or accuracy problem. Running high pressure loads I had some pretty flat primers but never blew one.

More recently, this year, I started loading 357 again and tested HS6 for moderate Rifle loads Using standard primers and had no problems. Matter of fact accuracy was excellent.

The only time I use magnum primers is for hot loads with H110.

Thanks for the replies. I’d prefer to stick with only one type of primers to avoid mixing them up anyway. Reason why I only use .45 ACP brass with small primers pockets. One type to buy and store and no chance of popping a large primer as I try to seat it in a small primer case that got by me. When I do load some up I’ll load a few with the small pistol primers and fire them off. If all is well, and I’m sure it will be, I won’t even bother with the magnum primers. By the way, I do not intend to load maximum charges anyway. I think Hodgson says 3.7 HP38 is a max charge for 158 grain LSWC. I intend to stay middle of the road as always and load 3.4-3.5 grains. Weigh every charge as always.

As always, this forum comes through for me. Thank you.

The size powder charge and burning rate dictates if a standard or magnum primer is used .
Large charges of slow powders, especially ball powders , will usually benefit from a magnum primer but just because the name says 357 Magnum ...it doesn't mean you must use magnum primers .
HP38 is a easy to ignite powder and will not require the use of a magnum primer . Check your load data ...it will specify the primer standard or magnum , best to go with the load data's primer .

Gary

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Certified Cajun
NRA Member

The 357 Magnum is one versatile cartridge and is an easy cartridge when it comes to reloading. You can use magnum or standard small pistol primers with the fast or medium burning rate powders and even 2400, which is a slow burning powder. The one time you really need to use magnum primers is with slow burning ball powders, these would be HS-6 and H-110/W-296. Using standard primers with these powders will result in erratic and often incomplete powder ignition.


For powder selection, I have used Bullseye and HP-38/W-231 in the 357 Magnum, but I will say that you have to be very careful as safe charges of these powders are small and take up little of the case's available capacity. It is very easy to double charge a case, which takes a perfectly safe load to a load that can damage or destroy a firearm and injure the shooter or anyone standing nearby.


With the exception of 148 grain target wadcutter loads, I prefer medium burning rate powders like AA#5 and Unique. They take up a lot more of the case capacity and a double charge is easy to see before the bullet is placed into the case mouth.

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VCDL, GOA, NRA

Most welcome. If you look at data from other sources than Hodgon you will find just regular old standard primers for other than a few slow powders.
In addition other sources (Speer, Hornady etc will have different powder charge min and max. There is some leeway between all of them. Different tests, equipment, date and time. They are all published to be within SAMMI specs

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Still Running Against the Wind

I'm using 2400 also and I've never used a mag primer with that powder. I consider 2400 to have a medium burn rate. HP-38 is a lot faster powder so the mag primer would be even less of a consideration as you say. I don't think HP-38 is an ideal powder for 357 velocities but the truth is there are many powders that will work in a 357 case. I've even loaded American Select in a 357 case with 38 spl velocities. Works fine. 357 is a very versatile revolver cartridge.

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That's just somebody talkin.

Use what you have. I no longer load any magnum handgun cartridges, but some years ago experimented with a load using the H&G #51 cast SWC (160 grs., the original .357 Magnum bullet) and #2400 powder. I got slight but measurably better accuracy using a magnum primer instead of a standard one. That's the results obtained in one 6" Python. That means absolutely nothing, like so many other loading tales often quoted.

Hope everyone can find enough primers of any kind to perform uninterrupted load development, a process that tells so much about your gun and what does best in it.

The right answer is the right answer, yesterday, today, and tomorrow.......
LOL

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dd884
JMHO-YMMV

YES! That is all I have ever used, with no problems since about 1970.

I load my .357 with 2400 and a Fed 100 (small pistol) primer. No problems and great accuracy.

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Common sense isn't so common.

Everybody overthinks primers. Fact is that any small primer (pistol, Magnum, rifle) will work fine for handgun loads. Only issue is whether if the handgun firing pin impact energy produces reliable ignition performance. SPM and SR primers are better for very high chamber pressures. Performance of all is essentially equal with any powder.

I read an article years ago by a gun writer who was privileged to see Elmer Keith's reloading bench after he passed on. The writer was somewhat surprised that he found NO magnum primers of any kind. Surprising from a gentleman who made his reputation loading everything to cylinder bursting pressures.

I know recommendations are to the contrary, but I haven't found a real need for magnum primers even when using 296/H110 or HS-6. Perhaps in extreme cold, like below zero, they might prove beneficial.

Except for 2400. Non-magnum primers preferred.

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Gun Control: POA=POI

A little off topic, but I once did some extensive testing of LRM vs. LR primers (CCI) using a slow propellant (I think it was Norma 205) in .270 Win with 130 gr bullets. Results were that both loads worked equally well, with near-identical average MVs. But grouping appeared slightly better using regular LR primers which may or may not be significant. Usual advice is that the .270 loaded with slow powders requires LRM primers. I did not find that to be the case, except maybe it might be true under some special circumstances, such as in very cold temperature environments.

Hodgdon doesn't make or test 2400. But yes, 2400 doesn't need a mag primer

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Still Running Against the Wind

Another off topic. The 357 mag originally had a LARGE primer.

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Still Running Against the Wind

My Winchester SPP's say: For Standard or Magnum. I don't know if this is the current wording or not.

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Fools despise wisdom.

Better double check, It is the Large primers that are both.

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Still Running Against the Wind

Thanks,
I may have been looking in the wrong drawer.
FWIW: I use standard and magnum SPP's interchangeably for all my .38 spec and .357 loads and have never noticed a difference.

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Fools despise wisdom.

I have used standard primers for 357 using 2400 without issue for years.

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Randy

You've had a multitude of responses telling you that it's OK to use SP-Mag primers in your 357 loads with H38, and I'm not going to disagree. My experience was with trying magnum primers vs SPP in 9mm mid-range loads using a different powder (AA#5, same load in all cases) and different bullets (124 gr plated HBFP). Here's some chrono results; 10 rds each from a Springfield 1911-A1:

Winchester SPP: Average 940 FPS, ES 44 FPS, SD @ 14 FPS
Federal Premium SPP: Average 930 FPS, ES 65 FPS, SD @ 22 FPS
Sellier & Bellot SPP: Average 920 FPS, ES 52 FPS, SD @ 18 FPS
CCI SP Magnum: Average 930 FPS, ES 49 FPS, SD @ 14 FPS

No appreciable difference with a fairly fast burning powder. -S2

...because I don't HAVE to use magnum primers.

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"He was kinda funny lookin'"

I agree with everything said here. You can load 38 or 357 without magnum primers by using faster powders. Only powder I use with magnum primers is H110 or W296. Never "load down" either of those powders either. Always stay between starting and maximum loads with those slow powders.

Read the primer manufactures discription for the use of the primers. Some are just for 357 mags. REM 5 1/2 is one.

Mag primers may have thicker cups. Less chance of a pierced primer. (In my M28-2)