Large Pistol vs Magnum primers chrono results

[mattri]

With components being scarce was wondering about the real world differences in loads using LP vs mag primers.

Load is 44spl level in 44 mag brass and SAA replica.

Virgin WW 44 mag brass trimmed to length, 7.5gr of TB and 180gr FTX seated to 1.61 with a nice Lee crimp.

30 rounds with Win LP netted an average vel of 850fps with a SD of 13fps, accuracy was on par with anything I can do @ 25.

30 rounds with Fed LP magnums netted an average vel of 850fps with a SD of 13fps, accuracy was on par with anything I can do @ 25.

No doubt others will have different results, especially at higher pressure/vel but this is what I found.

[Mal Paso]

Since there is little hard data on primers here are the best rumors.

Win LP are supposed to be hotter as they don't have magnum primers. One size fits all.

Federal Mag Primers are not hotter the brass cup is thicker to take higher pressure.

Testing like you did is the only way to know for sure.

[mattri]

Interesting hadnt heard that before, thanks.
I will primarily be using 44spl load data, just wanted to make sure I wouldn't see any big swings or spikes with the mags.

[downzero]

Are you saying you have an 1873 that is chambered in 44 Magnum? Who makes it?

[mattri]

https://castboolits.gunloads.com/showthread.php?428160-Just-picked-up-a-Uberti-Cattleman

[dale2242]

I think that to do your test right you need to use the same brand of standard and magnum primers.
I did my test with 45ACP reloads.
I used the same brand of brass, same bullet of the same alloy, same powder charge of the same powder.
The only difference was the primers. Primers were both CCI.
I fired 10 rounds of each from a 1911 and a Sig P220.
I got a 20 FPS increase in velocity with the magnum primers.
Accuracy was the same.

[Larry Gibson]

From a previous thread on this topic;

9mm; SP and SR primers
The last few months there have been several threads regards the use of SP magnum and/or SR primers in the 9mm cartridge. I had conducted a test of SP and SR primers in the 357 Magnum and posted the results [https://castboolits.gunloads.com/showthread.php?417830-Comparison-of-various-SP-and-SR-primers-in-the-357-Magnum]. In that cartridge with Unique powder there was enough evidence demonstrating the SP Magnum and SR primers could raise the psi enough to warrant caution in doing so.
However, does that correspond to the 9mm cartridge which was the subject of the question. Some definitely thought the substitution should not be made. Others were adamant that using a SP Magnum or SR primer in the 9mm with a given load posed no problem. A video showing a limited test by a commercial reloader demonstrated no different in pressure or velocity. Others stated they found little variance in chronographed velocity as proof there was no difference in psi. I proposed caution be used should it be necessary to substitute SP Magnum or SR primers in the 9mm with a given load.

I have just completed 3 additional more fairly comprehensive pressure/velocity tests of 3 different powders in the 9mm cartridge.
A commercial loader request I test the 9mm cartridge with CCI’s 500, 550 SP primers using 6.1 gr VV 3N37 under a 115 gr FMJ bullet. He supplied the powder and the bullets.
To provide a comparative reference I also loaded test rounds with the same primers using 4.9 gr Alliant Bullseye and the 115 FMJ bullets [listed as a maximum] and also included the CCI 400 SR primer and the CCI 450 SR magnum primers. Testing was done in a 10” Contender barrel with a strain gauge affixed and connected to the Oehler M43 PBL. The SAAMI MAP for the 9mm cartridge is 35,000 psi.

[B]The test of the comparative reference load [4.9 gr Bullseye] proved quite interesting. The test results briefly;

Primer, velocity average, psi average:

CCI 500 SP primers; 1331 fps, 35,000

CCI 550 SP Magnum primers; 1341 fps, 35,000 psi

CCI 400 SR primers; 1338 fps, 35,000 psi

CCI 450 SR Magnum primers; 1330 fps, 35,000 psi

Note the test to test variation in velocity is well within the test to test expected variation of the same load. What was really surprising was the pressure for each and every shot, regardless of the primer, was exactly the same…..right at the SAAMI MAP for the 9mm cartridge. Looking at the internals [time/pressure curves, area under the curve and rise to pressure] a slight difference could be noted. The CCI 550 SP Magnum and the CCI 450 SR Magnum primers gave slightly more uniform internals than either the standard SP or SR primers!

So why was there no increase or variation in psi with this load? In discussing this with a ballistic technician the answer is actually quite simple; the 4 gr powder charge of Bullseye will only produce so much psi regardless of the primer used to ignite it. All other factors be ing equal other than the primer used the 4 gr charge of Bullseye was giving all the psi it was capable of. With other powders the results can be very different as seen in the 357 Magnum test and the following 9mm test.

I then conducted the second test using the provide VV 3N37 powder. The test results;

CCI 500 SP primers; 1236 fps, 32,300 psi

CCI 550 SP Magnum primers; 1253, 34,500 psi

Note, with the use of VV 3N37 powder, we have a distinct difference in results with this test than with the previous test with Bullseye. The internal ballistic measurements again indicated the CCI 550 primer gave slightly more uniform ballistics. The CCI 550 Magnum primer also gave a noted increase in velocity [20 fps increase vs the 10 fps difference with Bullseye] and an increase in pressure of 2,200 psi.

In a previous thread it was Lloyd Smale (If memory serves me correct as I couldn’t find the thread with “search”] that was adamant with is 9mm load of HS-6 in didn’t matter with his mid-level HS-6 load what primer was used as all were “safe”. He also rather adamantly suggested I test HS-6 and find out. So I did.

Lyman lists 6.2 gr HS-6 as their max load under a 120 gr 356402 bullet. I didn’t have the Lyman bullet but have the Lee 120 gr TC bullet [123 gr cast of COWW + 2% tin], so I chose to use that load. Even though Lyman lists that load as “max” the CUP measurement of 29,300 indicates it is not a “max” load as the CUP SAAMI MAP is 33,000. I have on hand 13 different SP and SR primers [7 SP primers and 6 SR primers] so I loaded up a test with each of them.

Again, the test load was 6.2 gr of Hodgdon HS-6 under the 123 gr Lee TC cast bullets.

The test results by primer used;

Small Pistol primers;

Federal 100 SP primer; 1255 fps, 34,800 psi

CCI 500 SP primer; 1227 fps, 34,700 psi

Magtech 1 ½ SP primer; 1243 fps, 35,000 psi

Winchester WSP SP primer; 1247 fps, 35,000 psi

CCI 550 SP Magnum primer; 1210 fps, 34,400 psi

Federal 200 SP Magnum primer; 1214 fps, 34,700 psi

Winchester WSPM SP Magnum primer; 1253 fps, 35,000 psi

Small Rifle primers;

Remington 7 ½ SR Primer; 1229 fps, 34,700 psi

Winchester WSR SR primer; 1220 fps, 34,800 psi

CCI 400 SR primer; 1237 fps, 34,800

Federal 200 SR primer; 1253 fps, 34,800 psi

CCI 450 SR Magnum primer; 1228 fps, 34,700 psi

Federal 205 SR Magnum primer; 1222 fps, 34,500 psi

Appears Lloyd was certainly correct, there really isn’t much difference regardless of the primer used. Also. interesting to note that 3 of the SP primers pushed the psi right to the SAAMI MAP whereas none of the SR primers did. That is one of the things I really like about this game and that is I’m always learning. In this case I’ve not only learned from actual testing but also through research to find the facts about primers. Turns out, once again, I and most others were misled over the years into thinking SP magnum primers and SR primers would increase the psi with a given load because they were “hotter” or had more explosive power. Turns out that isn’t true. The primers only hold so much compound and the energy produced by that amount of compound is finite. Thus, SP and SR primers essentially hold the same amount pf priming compound which essentially increases the same amount. SPM and SR/SRM primers apparently do not increase the psi per se by themselves. The difference is in the priming compounds and how they “burn”. The SPM and SR/SRM primers compound gives a longer flame burn is all.

So, if that is the case then why did two of the tests [the 357 magnum with Unique and the 9mm with VV 3N37 powders] show a marked increase in psi with the SPM and/or the SR/SRM primers? The answer to that appears, at least so far, to lie in the nature of the powder used. My guess at this time is any real potential increase in pressure with the use of a SPM or SR/SRM primer will be dependent on what kind of powder is used [single or double based], the kind of deterrent [controls the burn rate] that is used and probably any flash retardant used. Thus, as it turns out, all who participated in the past thread were essentially correct some of the time and potentially wrong at other times. This is evidenced as I’ve not found any conclusive evidence one way or the other to definitively say substituting a SPM or SR/SRM primer in a 9mm load is safe because, like many things we’ve found in reloading, it depends.

I will still, as of this writing, stand by my original suggestion; if one has to substitute a SPM or SR/SRM primer in the 9mm cartridge for a load proven safe with a SP primer developed load then use caution.

[MUSTANG]

:goodpost:

[Cosmic_Charlie]

My rather unscientific take at least with pistol loads is that as long as you are not loading near maximum data you should have no problems. A bit more caution perhaps with fast powders like Titegroup, Bullseye or VV N310.

[mattri]

I think that to do your test right you need to use the same brand of standard and magnum primers.
I did my test with 45ACP reloads.
I used the same brand of brass, same bullet of the same alloy, same powder charge of the same powder.
The only difference was the primers. Primers were both CCI.
I fired 10 rounds of each from a 1911 and a Sig P220.
I got a 20 FPS increase in velocity with the magnum primers.
Accuracy was the same.

Lol are you saying that my singular test wasn't 100% scientific and definitive:o

[onelight]

Thanks again Larry for testing and posting your results ��

[dale2242]

mattri, No but neither was mine.
Just a fun little test.
I will always go with Larrys results as more scientific and definitive.

[QuackAttack24]

Larry,

Thanks for posting these results. With component shortages, we all find ourselves scrambling for substitutes to use in place of what we're lacking. For me lately, it's been SPP. I've been using SRP as many have posted about on different forums. It's nice to see the data confirming what I've noticed, which is that there seems to be no difference in velocity or accuracy.

[MUSTANG]

I loaded up a lot of .38spcl/.357, 9mm , 40S&W, and .45 ACP for friends (including several living across the country from us) who could not buy ammunition or even worse, "Discovered" they needed to buy a firearm and learn to shoot because of the rising violence in the cities/suburbs over the last 24 months. When I began to run out of small pistol primers in the loading bench storage area; I went to my "Reloading Shed Storage" and discovered my stock of Small Pistol Primers was almost zero and limited Large Pistol primers on hand.

This induced me to start loading .38 Spcl and 9mm with Small Rifle Primers. I found the CCI 400 rifle primers worked well and had no issues in either 9mm or 38/357 handguns I used. Unfortunately; I got 2% to 5% failure to fire if I used CCI- #41 (MilSpec .223 primers) Small Rifle Primers in 38 Specials (variety of S&W Handguns); but have not had failure to fire in same for 9mm (Beretta, Luger, and others). I continue to look for Small Pistol Primers; but will use the CCI 400's if I have to since I still have a good store of those (but will avoid the CCI- #41 for this alternate application of small rifle primers for small small pistol in handguns).

As we continue to see if the primer issue will change; I am looking at what to do in the Large Pistol area as I am short supply on those too. Unfortunately there is a dimensional difference between the Large Rifle and the Large Pistol Primers.

286722

That difference between the Large Rifle Primer Max Height of 0.1320 and the Large Pistol Primer Max Height of 0.1250 looks small; but will result in high primers in a Large Pistol Pocket. If we do not see availability of Pistol Primers in the next few months; I may have to select out several hundred .45 ACP cases and ream the pockets to the same depth as a Large Rifle Primer pocket. Just as with the previous description on my use of Small Rifle primers in place of Small Pistol primers; I foresee that I may need to use the CCI-200, and avoid the use of CCI - #34 (intended for 7.62x51).

[Hanzy4200]

This proves what a lot of us have been saying for a long time. Many people have the misguided idea magnums drastically increase pressure and velocity.

[Taterhead]

Great post Larry. Thank you for the great work and great write up!

[Wisest.fool]

Wow. Very useful information. Excellent post. I had been wondering this myself. I'm down to the last 500 small pistol primers and was considering trying this but decided to err on the cautious side since I have had a catastrophic malfunction.

[William Yanda]

Since there is little hard data on primers here are the best rumors.

Win LP are supposed to be hotter as they don't have magnum primers. One size fits all.

Federal Mag Primers are not hotter the brass cup is thicker to take higher pressure.

Testing like you did is the only way to know for sure.

Thanks for that info. My question involved substituting SPM in rifle loads. My current thinking is caution necessary, but very possibly ok.

[Cosmic_Charlie]

I tried small pistol magnum primers once in .223 and got pierced primers and gas cutting on the bolt face.

[mattri]

Interesting. 223 is rated to 55k psi, wonder if that is too much for the pistol primers? Even 327 is only 45k.
It seems that running reduced loads (like 44spl in 44 mag) keeps the variance to a minimum.

[Larry Gibson]

I tried small pistol magnum primers once in .223 and got pierced primers and gas cutting on the bolt face.

Apples and oranges.....good lesson learned w/o too much damage.

This thread is in regard to pistol cartridges that generate much less psi than cartridges, particularly rifle cartridges, that develop a lot more pressure. Even some of the newest handgun cartridges that develop high psi's should be used with the recommended rifle primers with top end loads.

[centershot]

Very interesting data presented here, a "Thank You" to Larry for his work with the Oehler ballistic lab!

I, like most here, use a combination of flake, stick and ball powders. Some require a magnum primer for best ignition. I found myself having to stock mag primers for those powders and "regular" primers for others, just as most of you guys do. It seemed like I was "spending money twice", if you know what I mean. So, I stopped buying regular primers. I reasoned that the mag primer will work with any powder if it will work with powders that are harder to ignite properly. OK. Now, I don't shoot bullseye pistol, or any other game where a small increase in group size will cost me the match. I have found that mag primers work perfectly in my loads, light or heavy, and I don't need to buy two types of rifle and pistol primers. Even in my gallery loads for indoor range use, 5 grains of Bullseye and a 180 gr. cast boolit sparked by a mag primer works great. I've never been left wanting better accuracy that I couldn't get with a little load development. YMMV.

[MessybearII]

Great info Larry!
If you guys are interested in the large pistol side of things, and want to know more about large pistol primers in lab testing, contact the head ballistitian at Western Powders.
He can provide pressure results from ball Powders and different primers in the lab.
Pressures were VERY impacted by primer changes! Again this is lab testing.

[David2011]

Mattri, a best guess would be that with TB (assuming you mean Trail Boss) you can't pack enough powder into a case to get high pressures. As with Larry Gibson's data and Bullseye, a case full of TB will only develop so much pressure regardless of the primer used. As others stated, I would expect different results with different powders.

[MT Gianni]

Do not expect primers bought in the last 5 years to have the same formula make up as those from 25 years ago. As with all things we reduce when changing components and retest.

[MUSTANG]

Do not expect primers bought in the last 5 years to have the same formula make up as those from 25 years ago. As with all things we reduce when changing components and retest.


Good point. Also; reliability can change over time. I can remember a single incident of a primer that "Failed to Fire" for me between the 1970's up to 4 years ago. I can look at my reloading/test firing notes and see at least 2 dozen "Failure to Fire's" since January 2019 using "Current Production" primers (These are NOT part of my testing using primers for rifles in pistols; not my "Reloading" primer efforts). Small sample of one person; but my observation is that today's production of primers has less quality control based on "Failure to Fires".


Taking that observation in a different direction; I collected maybe 5 or 6 rounds on ranges during the 1970's to 2019 period of commercial ammunition that had primer strikes but did not fire; but I have almost three coffee cans full of various caliber/manufacturers commercial rounds with primer strikes but "Failed to Fire".

[fredj338]

What I have found in several caliber is it is all about the powder burn rate. Faster powders dont seem affected as much with the mag primers. Slower powders show a greater affect. In my 357sig load running std vs mag primers using AA#9, mag primers are 100fps faster.

[charlie b]

Interesting about failures. I shoot more now than I ever did, but still only a few thousand in a year. The past three years I have not had one primer failure.

[fredj338]

Do not expect primers bought in the last 5 years to have the same formula make up as those from 25 years ago. As with all things we reduce when changing components and retest.

You of course have something that substantiates that? Unless you are running max loads, any modest primer compound change isnt affecting pressures.

[fredj338]

Interesting about failures. I shoot more now than I ever did, but still only a few thousand in a year. The past three years I have not had one primer failure.

Only primers I have ever had issues with were Wolf SP. I would never rely on them for anything serious.

[Thin Man]

I work at a commercial shop that has an indoor range. For the past 10 years I have seen a small but regular amount of FTF rounds turned in to us. With the vast majority I find the fire pin indent in the primer is very shallow from a light hammer/strike impact. The second most common FTF rounds are the primers where the fire pin struck well off-center of the primer. It was common that I would re-test these rounds (loading a single cartridge only) in a known reliable firearm to re-test and the vast majority of these did fire. The third lot of tests involved grand-dad's old handgun with the aged ammo he had bought when he got the firearm. These rounds usually did not fire. Just more to ponder.