Magnum primers - any disadvantage ?

[BobC]

I am contemplating using only magnum primers for my 38/357 loads. The small price premium seems insignificant compared to the hassle of labeling empty, but primed, brass.

Assuming one does not substitute a hotter primer in an already maximum load, are there any problems with using mag primers for loads which were developed with standard primers?

As a related question:
Why does Winchester market a combined std/mag primer for large pistol but carries the two types for small pistol?

 

[stans]

Magnum primers usually cost more than standard primers and may provide a hotter flame. The increased ignition pressure may present problems with getting low velocities with wadcutter loads. I have found that the only pistol powders that might benefit from magnum primers are W-296, H-110 and maybe AA#9. All other pistol powders seem to do just fine with standard primers. So I ask you, why would you want to buy just magnum primers?

 

[KP95DAO]

I have switched to WSPM primers for all my "standard" 9mm, 40S&W, and 357 Sig rounds. I can get the mag primers for the same price as WSP primers so they don't cost more and I find they give a more consistant and higher velocity load. This also allows a slightly lighter powder load for the same velocity.

I use CCI 400 primers in all my "hot" loads.

 

[BobC]

Stans:

Since my sources for primers charge essentially the same for standard and magnum primers, I was wondering if I could select just one type and use it exclusively. (I like to size, bell, and prime cases in advance of loading. Since I don't know how to look at a primed case and determine what type of primer is seated, I could either standardize with one primer type or mark all prepared cases as to which type primer is used.)

Several reloading books, e.g., Lyman, specify use of magnum primers for their entire selection of 357 loads (regardless of powder).

My situation amounted to:
1. Do I use standard primers and violate the Lyman loads for 357, or
2. Do I use magnum primers and "overdrive" the 38 special loads?

It now sounds like I could use standard primers for all 38 & 357 loads, and, as an exception, use mag primers only for those specific powders called out in the Speer reloading book as needing a mag primer.

 

[Quantrill]

Bob,
The NRA did a accuracy test a few years ago for .38 sp. and it was written up in the NRA Cast Bullet book. In it they found that a switch to Magnum primers DOUBLED the group size for target loads.Since I need all the help I can get, I now only use Magnum Primers in those loads that specifically specify them. Quantrill

 

[popbang]

I have been comparing standard and magnum primers this past winter. The magnum primers are giving more consistant velocities across the temperatures. The standard primers are getting lower velocities and larger deviations.

I am going to collect more numbers.

 

[stans]

I have heard stories of magnum primers causing accuracy problems and I have heard stories of standard primers causing accuracy problems. Perhaps it is more of a function of what a particular gun likes best? This could lead to a lot of test loads and range time, which is not necessarily a bad thing!

 

[Phil in Seattle]

I have found that the only pistol powders that might benefit from magnum primers are W-296, H-110 and maybe AA#9.

AA#9 in 357 definitely needs a magnum primer. I know because I made loads that went piff instead of bang.