DONT EVER TRY THIS AT HOME....or anywhere else for that matter !
Read the first line. If any questions, read the first line again.
Hopefully thats enough disclaimer.

We all know that large magnum rifle primers are “hotter” than a small pistol primer. Particularly a WLRM compared to a Rem 5 1/2.
Todays test used a 308 I have built for myself. Rem 700 action, Lilja barrel.
First string: Starline brass, Rem 5 1/2 primer, 34 grains H4198, 168 MK. Average speed for four five shot groups was 2403 fps. This load is in the Hodgdon book.
Second string: Hornady brass, WLRM, 34 grains H4198, 168 MK. Average speed for four five shot groups was 2394 fps.
Slower with a magnum rifle primer than a small standard pistol primer.
Both loads shot well, neither being better. If I had shot both strings at the same target, group would have been less that 1.25 inch.

Running the same test with H4895 in a few minutes.

Silly question, doesn't the rifle's firing pin puncture the small pistol primer?

Interesting data. Do you have a way to measure pressure? I remember part of an Rick Jamison article on primers differences. He measured large differences in peak pressure between primer types and brands that otherwise showed small velocity differences. I think he attributed it to the varying brisance properties of the primers.

Aren't the 5 1/2's small pistol magnum primers?

The Remington 5 1/2 Small Mag Pistol Primers are made with a very closely controlled, specifically formulated chemical mixture to ensure that no matter the powder, ignition is always fast and consistent. The primers are made with a three legged design that gives the largest area for the flash and a bigger striking area for the firing pin. The 5 1/2 Small Mag Pistol Primers are designed and tested to function in extreme temperature ranges from -20°F to +150°F. Each 5 1/2 Small Mag Pistol Primer is produced to exacting tolerances with a deviation no larger than .0003 ounces. All 2 5 1/2 Small Mag Pistol Primers are visually inspected and undergo critical ballistic tests.

Summary

The Remington 5 1/2 Small Mag Pistol Primer is a premier tripod designed flash cup with a larger than standard striking area that ensures positive fast ignition of most all available powders with a weight consistency of .0003 ounces. All 5 1/2 Small Pistol Primers are tested in controlled scientific environments for ballistics performance and quality. The 5 1/2 Small Pistol Primer will perform from -20°F to +150°F to ensure no matter where you use them, they will perform at the top level.

Specifications and Features:

Designed To Perform From -20°F To +150°F
Weight Checked To .0003 Oz
100% Visually Inspected
Tripod Anvil Design Gives Large Flash And Larger Striking Area

Charlie,
Did you see a significant difference in ES between the two primers/loads?

Here is the new data:
Again, dont do this at home !
Starline brass Rem 5 1/2 primer, 42 grains H4895, 168 MK...four five shot groups. Average speed 2592 fps
Hornady brass, WLRM, 42 grains H4895, 168 MK....four five shot groups. Average speed 2597 fps.

Phasmid
I can measure pressure but I didnt want to spend the time or the money today .
Charlie

Aalf
The primers I have make no mention of being magnum. Nowhere. Neither on the case box or the individual boxes. I would speculate that if they were considered “magnum” then Remington would have noted that somewhere on the package. But who knows......we are talking about Remington..
Charlie

Alpinecrick
On the H4198, one was 12 SD and the other 11 SD but I dont remember which.
Charlie

Thanks for the information, Charlie. What was the ballpark ambient temperature where you were doing the shooting?

Its about 36 degrees F here today .

Elkhunterm
Not a one.

Funny, in my googling around, I found pictures showing boxes that don't show them as magnum, but the descriptions say they are.

Then I found this post on another site from 6/2020:

Figured I would make a post about these Remington 5 1/2 small pistol primers. I bought some a while back. I was loading some 9mm early last week and used some of the 5 1/2s I bought to test out. I didn't get to load them that day so they went in with other primed cases I had ready....pretty much all CCI SP. I usually keep around 600-700 9mm cases size and primed and ready for loading at any given time. So after I loaded up 200 rounds, I came across some Remington small pistol 1 1/2 primers in a store. So I wondered what the difference was. The general consensus online was the 5 1/2 primers are magnum. Well, they don't say magnum on the box. I do use SP magnum, and have plenty in CCI and Win...but use them in 357 Mag. So now I get aggravated as I'm thinking I'll gonna have to pull all those rounds apart to find those "magnum" primers somehow. I did go through all my primed cases, very time consuming. I'm pretty sure I found over half of them from what I could see through the flash hole, comlared to the color and appearance of the anvil of new primers in the box. Did some more online research, searched Remington's site, no additional info on the differences. Just says not to use the 1 1/2 primers in higher pressure rounds like 357 Mag, 357 Sig, 40 S&W. I found where others stated the 5 1/2 primers were not magnum, but just a thicker cup. So I ended up just calling Remington today myself. They told me they are NOT magnum primers, but just a thicker cup for higher pressures. Just standard small pistol, same amount and mix of priming compound used in the 1 1/2. A lot of people believe they are magnum, just wanted to put it out there that they are NOT per Remington.


Now if you want more confusion, JB says otherwise:

http://www.sksboards.com/smf/index.php?topic=56422.0

Thanks Charlie.

Thanks for reporting the test, Charlie--partly because it fits into my experience that primer differences tend to matter most in either very small or very large cartridges, and especially not with extruded powders. Just one question: Did you weigh the two brands of brass?

Don't know if there's a more "medium" cartridge than the .308 with 165-168 grain bullets.

Any difference in case capacity between Starline and Hornady?

Thanks,

John

John
In the case of the large cartridges, was that with faster burning powders? If so, would that suggest faster burning powders are more sensitive to primer types and brands?

aalf,

Don't see where Remington 5-1/2 primers were mentioned that link. Also, please not that "article" was put together from SOME of my info and a variety of other sources.

I didnt weigh any of that brass. I’ll try to remember next time.
Charlie

There is a lot information on primers out on the internet. I found these links below in one search. I don't know how rigorous the testing was. I just try to use what matches the reloading data I am following. I think it was "Scenar Shooter" that wrote that SR primers can have trouble with consistent ignition/accuracy in medium capacity cases in the extreme cold weather he hunts coyotes in. I also remember he was using the Russian primer brand with great success.

http://www.accuratereloading.com/primer.html

https://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

http://castingstuff.com/primer_testing_reference.htm

http://bulletin.accurateshooter.com/2017/04/ultimate-large-rifle-primer-shoot-out-16-types-tested/

tag

In the handloads.com chart on primers, the 5 1/2 primers are listed as small pistol magnum primers. In a box of 5 1/2 primers I see no mention of "magnum". I am getting long in the tooth and can easily be befuddled. I had to print out that chart to cross reference etc. I took a picture of this chart and it is below



I might add that Remington 6 1/2 primers are not designed to be used at some of the high pressures some cartridges are loaded to. They are good for 222 pressures though.

I think we used to do something called a "T-Test" in an attempt to determine is a difference was real or simply "lost in the noise". I don't recall the math right now. One thing I think we needed was sample size.

I see you reference "Average speed for four five shot groups." Is that the average of 4 averages or the average of all 20 shots?

A rough rule I've used is ES about SD x 3. It doesn't always hold true but is usually pretty close. If that holds true here, you had ES of about 36 on one test and 33 on the other.

I've shot two tests of the same load in the same rifle and seen similar differences between the averages. Seeing 9 fps in the 2400 fps range and 5 fps in the 2600 fps range, gut reaction is "There is no difference".

Great data, Charlie. Thanks for sharing.

If someone wants to supply the data, I would be happy to do the T Test and report back. That is the correct test for distinguishing real change from random noise.

Small Handgun Magnum .017" cup thickness

CCI 550 See Note 1 at the bottom of page
Federal 200
Federal 200M - Match version of above
Magtech PR-SPM
Remington 5 ½
RWS 4047
Winchester WSPM
Wolf/Tula Small Pistol Magnum SPM #KVB-9M - brass cup - "For Magnum Pistol loads"

aalf,

I don't GAS about the notes at the bottom of the page.

My point was that NONE of the information in the post that was lifted (illegally, according to U.S. copyright law) from my article on primers mentions Remington 5-1/2 primers. In fact I don't recall ever using any 5-1/2s, and don't have any on hand..

The so-called article was a mish-mash of various Internet stuff. So no, your following statement is NOT true:

"Now if you want more confusion, JB says otherwise: http://www.sksboards.com/smf/index.php?topic=56422.0"

Well excuse me all to hell, wasn't my intention to get you all butt hurt......

Wasn't butt-hurt much, partly because you obviously didn't understand the situation. Which is why I pointed out what was going on. But was also not butt-hurt much because anybody who writes for a living will always get some flak.

But as a professional writer, I also do NOT like somebody attributing some statement to me that I never made. Which is exactly what you did.

Also did not like the website mixing my stuff up with that of other's--and as I pointed out, illegally. But this happens so frequently on the Internet that unless an author is willing spend money on a lawyer and court case, it's not worth it. Partly because websites that do that sort of stuff aren't making enough money to bother with anyway. And if somebody does go after them, they tend to fold up the tent and start another site.