WSP primers versus WSPM [9mm Luger, 38spl/357mag]

T

TheGuyOfSouthamerica

Moderator
Hi all,

Do I have to back off powder Charge when using Winchester Magnum primers in 9mm Luger or 38 spl/357 mag?

Anyone measured velocity differences with the same powder Charge but just WSPM instead of WSP primers?

I appreciate any data.
 
Everything I have ever read definitely advises to back off a bit on the powder and see how it reacts. IE look for pressure issues.
 
I wonder of which amount we speak when we say backing off the powder (when using magnum primers).

1 grain, 0.1 grain or what?

I do not get anyways magnum primers (WSPM) but for curiosity sake how much powder I would save if I would use Magnum primers instead of WSP.
 
Look in your reloading book and see what they used when making the data. Most of them are very specific on what they used.
 
I wonder of which amount we speak when we say backing off the powder (when using magnum primers).

1 grain, 0.1 grain or what?

I do not get anyways magnum primers (WSPM) but for curiosity sake how much powder I would save if I would use Magnum primers instead of WSP.
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Use a percentage rather than just a number. Some powders use very small weights and 1g would be a lot. Some use more weight and 1g would be small. Try 10% below what you're using now and see how it works. I thought recent Winchester primers were using the same primer for magnum loads as non-magnum loads.
 
Jim Watson:
I'll be running standard vs magnum primer comparison next week.
CCI though.
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I did that this past summer but used rifle. The rifle is an old Remington 700 series having a 1:12 barrel twist. Caliber .223 Remington. The load data was:
Powder: Hodgdon H335
Bullet: Sierra 53 grain Match King HPBT
Brass: 1X Fired LC-11
Primer 1:CCI 400
Primer 2: CCI 450
Primer 3: CCI BR4
Primer 4:CCI #41

The CCI 450 and CCI #41 are both classified as a magnum primer. I shot ten shot groups over my chronograph and more effort was placed on shooting over the chrony that my target but overall at 100 yards the groups weren't that bad. Here are the average velocities for the four primer types used:

Primer%20Test%201.png


223%20Primer%20Test.png


CCI 400 Primer: 3372
CCI 450 Primer: 3366
CCI BR4 Primer: 3384
CCI #41 Primer: 3418

Sort of interesting that the CCI 400 Standard Small Rifle primer yielded a slightly lower velocity than the CCI 450 Magnum Small Rifle primer.

While not a maximum charge weight (Sierra 50th Anniversary Manual) it is pushing it. None of the cases showed any pressure signs after firing All of this leads me to believe while it is prudent to reduce loads when changing components the difference between CCI Standard and Magnum primers with H335 (Ball Powder Propellant) was not that great. This was a typical early summer day with outside air temperature around 75 Degrees F. and the rifle and ammunition all stable to that temperature.

Would love to see more similar test results.

Ron
 
Keybear:
when using Winchester Magnum primers

OK When did Winchester START making Magnum Primers ?
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The Winchester primer lineup looks like this:
SYMBOL PRIMER TYPES
W209 #209 Shotgun Shells
WLP #7 - 111 Large Regular Pistol
WLR #8-1/2 - 120 Large Rifle
WLRM #8-1/2M - 120 Large Rifle Magnum
WSP #1-1/2 - 108 Small Regular Pistol
WSPM #1-1/2M - 108 Small Magnum Pistol
WSR #6-1/2 - 116 Small Rifle

There is a quirk with Winchester WLP (Large Pistol) in that WLP has on the packaging Large Pistol, for Standard or Magnum pistol loads. Meaning that Winchester does not make a separate primer for Magnum and Standard in their large pistol (WLP) line.

Asto Magnum primers in general? The harder to ignite ball or spirical powders (ball is a trademark of Olin and spirical is trademarked by Hodgdeon) during the early 1930s but with the onset of WW II did not gain in popularity until the early 50s. My guess and purely a guess is that magnum primers came into their light during the early to mid 1950s as the new powders became popular. Again, purely a guess and nothing more.

Ron
 
Most of the credible reports I've seen online seem to think that in pistol rounds like 9mm and 38 special that magnum primers generate 10 to 20 FPS more than regular primers. This difference basically is within the typical velocity spread and only noticeable if keeping detailed records and using a chronograph.

Dropping the charge down .1 to .2 grains might be prudent if at the max load.
 
For a new reloader (someone with limited experience and asking this question), primers are largely dependent on powder type. Slow pistol powders need a Magnum primer, like W296/H110. Most other, faster powders will perform well with a standard primer, regardless if the cartridge is named "Magnum" or not.

As any new load, start with the starting loads listed in your reloading manual. If you only have Magnum primers, you won't need to reduce the charge from listed starting loads and you will stick with all the same components during your "load work-up". Different combinations of components will result in differences in performance/accuracy, that's why some reloaders get better accuracy with Magnum primers and their other components. It is good reloading practice to drop powder charges with any change of components, just to make sure the change doesn't result in unexpected consequences.

Yep, pressure will prolly be a bit higher, but you will not be starting near max., so you'll be safe...
 
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