Excerpt from the CBA forum.


Most likely your load of 3.4 gr O W231 is generating all the pressure it will in the 38 SPL case regardless of the primer used.  That small charge of a fast burning easily ignited powder contains only so much energy....period.  Modern magnum primers do not have a "hotter" or higher level of pressure.  They are formulated to give a longer burn time.  This may increase pressures with many of the slower burning powders.  Perhaps the following test results of various primers in the 9mm and 357 Magnum will provide some realistic insight.  I would not expect results from substitution of primers to be much different in the 38 SPL cartridge.

 

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 HERE.  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 chronograph 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 [Bullseye, VV 3N37 and HS-6] 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.

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! 

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; [COLOR="#FF0000"]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. [/COLOR]

 

Comparison of various SP and SR primers in the 357 Magnum

Give the panic buying, hoarding and shortage of firearms, ammunition and reloading equipment and components several recent threads have asked if it is "safe” to use, in lieu of standard SP primers, magnum strength SP primers or even SR primers.  This question pops up every now and then but the recent numerous queries on this topic seem to be driven by the dire shortage of primers.  Some reloaders have no standard SP primers with no prospect of obtaining any in the foreseeable future at anything resembling a reasonable price.  They do, on the other hand have SP magnum or SR primers both of which fit the primer pockets of handgun cartridges using a SP primer.

 A recent video by a small ammunition manufacturer indicated switching from a standard SP primer to a SP magnum primer of the same manufacture posed no problem in the 9mm P cartridge with the given load tested.  They tested on the video two 3 shot test of that load to get three shot tests of pressure and of velocity.  While there appeared to a mild increase in psi and velocity when the SP magnum primer was use with that load the difference did not seem to be too much.  I had reservations about that as the test sample was too small and the load (powder and charge) was not given. 

While I had not specifically tested a direct comparison between different types of primers I had, from previous chronographing and pressure measurements, formed an opinion that, while some switching of different makes and types of primers seemingly made little difference, switching primers can sometimes give sufficient differences, particularly in pressure.  I, of course, referring to small handgun cartridges using the faster burning powders.  The results of this test should in no way be construed as a blanket statement or rule of thumb.  There are just too many variables concerning the volume of cartridge cases and, probably most importantly, the ignition and burning characteristics of slower burning powders.  The results of this test apply to the use of the easily ignitable fast burning powders used in small handgun cartridges. 

Thus, to find an answer to the question [Can SP magnum or SR primers be substituted for SP primers in the smaller cartridge cases with a given load?]  I rummaged through my supply of SP and SR primers and came up with five different SP primer make/types to test;

CCI 500

Federal 100

Winchester WSP

CCI 550

Federal 200 Magnum

I also came up with five SR primer make/types to test;

 Remington 7 ½

CCI 400

Winchester WSR

Federal 205 Magnum

 

CCI 500

While there are other such primers I feel a sample of 10 different primers should give us an idea of the potential pressure increases and some aspect of whether or not substituting primers might be "safe”. 

Thus with that selection of primers I prepped 100 Winchester 357 magnum cases [ten shot test with each primer] .  I selected a load to use with all the primers that was a mid-range 357 magnum load [based on previous chronographing] which should give a bit of "fudge” room if the psi’s did get too high with any primer.  The load I selected to use was 6 gr of Alliant Unique under a 358156 cast of COWWs + 2% tin, sized .358, Hornady GCs crimped on and lubed with BAC.  The bullets were seated, and roll crimped in the front crimp groove giving the loaded OAL at 1.597”. 

The SAAMI MAP for both the 357 magnum and the 9mm P are 35,000 psi.

The test firearm was my Contender 7.94” barrel with the strain gauge located over the chamber as per SAAMI specification.  The strain gauge was connected to the Oehler m43 PBL.  Test conditions were a reasonable 60 degrees with 30% humidity and little to no wind.  The velocity listed is muzzle velocity as the M43 corrects the screened velocity to the muzzle.  The Oehler Sky-screen start screen was 10’ from the muzzle. 

All results are based on the 10 shot test string for each primer. All the time/pressure curves (traces) appeared normal for the test firearm. The results are listed by primer.  Since the thrust of answering the question has to do with pressure that is the focus of this test.  I shall make comments after the data for each primer is listed and also in conclusion. 

Test results;

CCI 500 SPP primer

Average velocity; 1178 fps, SD 11 fps, ES 38 fps.  PSI average; 25,700

 SD 2,100, ES 5,700, high psi was 29,200 and the low psi was 23,500.

 This is a particularly good load.  The internals are excellent as shown by the low SD/ES of both velocity and psi.

 Federal 100 SP primer

 Average velocity; 1189 fps, SD 10 fps, ES 36 fps.  PSI average; 27,900, SD 1,700, ES 5,500, high psi was 30,300 and the low psi was 24,800.

Another excellent load but we see a slight increase in velocity and psi.  The 11 fps increase in velocity equated to an increase of 2,200 psi.

Winchester WSP primer

 Average velocity was 1175 fps, SD 18 fps, ES 60 fps.  PSI average; 26,300, SD 3,400, ES 9,900,

high psi was 31,700 and the low psi was 21,800. 

This primer is supposed to be of stronger brisance as it is intended to ignite ball powders.  We see a velocity and psi comparable to the previous two primers, but we also see a much larger SD and ES of both velocity and psi.  Two of the tested rounds gave a psi above 30,000.

 CCI 550 SP Magnum primer

Average velocity was 1179 fps, SD 17 fps, ES 60 FPS.  PSI average: 27,500, SD 3,900, ES 13,500, high psi was 35,300 and the low psi was 21,800. 

This SP magnum primer showed no increase in velocity or in psi averages.  However, obviously the internal psi created with what was supposed to be a "mild” 357 magnum load of Unique demonstrates something is amiss here given the somewhat erratic internal ballistics.  Two the tested psi’s were above 30,000 with one exceeding the SAAMI MAP for the 357 magnum.  

Federal 200 Magnum SP primer

Average velocity was: 1176 fps, SD 14 fps, ES 43 fps.  PSI average: 27,100, SD 2,700, ES 8,800, high psi was 32,000 and the low psi was 23,200.

Again, this magnum SP primer gave no increase in average velocity or psi.  Yet the wide SD/ES of the psi measurements indicate somewhat erratic performance.  The 32,000 psi shot gives cause for concern.

 Remington 7 ½ SR primer

 Average velocity was; 1184 fps, SD 20 FPS, ES 78 FPS.  PSI average: 28,100, SD 2,800, ES 9,100, high psi was 32,000 and the low psi was 22,900.

 Except for the much larger SD/ES of the psi this SR primer gave similar performance to the Federal 100 primer.  We must note that two of the tested shots exceeded 30, psi with this primer but not with the Federal SP primer.  A noticeable difference.

CCI 400 SR primer

Average velocity was: 1188 fps, SD 15 fps, ES 52 fps.  PSI average was 29,200, SD 3,700, ES 12,200, high psi was 35,100 and the low psi was 22,900.

Quite erratic yet the chronographed velocity does not indicate that.  No appreciable gain in average velocity yet a 2-3,000 psi gain is apparent in the average psi.  Five of the tested ten shots gave psi above 30,000 with one exceeding the SAAMI MAP. 

Winchester WSR primers

Average velocity was: 1173 fps, SD 17 fps, ES 50 fps.  PSI average was:  27,600, SD 3,800, ES 9,100, high psi was 32,600 and the low psi was 23,500 psi.

Again, erratic internal psi yet not apparent based on the "normal "chronograph measurements.  No appreciable increase in velocity or psi as shown by the "average” of each yet 4 of the tested shots exceeded 30,000 psi. 

While there are other such primers I feel a sample of 10 different primers should give us an idea of the potential pressure increases and some aspect of whether or not substituting primers might be "safe”. 

 Federal 205 SR Magnum primer

 Average velocity was: 1185 fps, SD 16 fps, ES 63 fps.  PSI average was: 29,700, SD 2,400, ES 8,200, high psi was 34,000 and the low psi was 25,800.

Again, erratic psi performance not belied by the chronographed velocity measurement.  Three of the tested shots exceed 30,000 psi with one approaching the SAAMI MAP.

CCI 450 SR primer

Average velocity was: 1171 fps, SD 15 fps, ES 47 fps.  PSI average was: 28,000, SD 2,400, ES 6,900, high psi was 31,000 and the low psi was 24,100.

No gain in velocity, small gain in psi with three of the tested shots above 30,000 psi.  Appears to be the mildest of the "magnum” strength SR primers tested. 

 

So there’s the data which brings us back to the question:  is substituting a SP magnum primer or a SR primer for a standard SP primer "safe” in a small handgun cartridge?  The answer is somewhat of a conundrum. If the load with the standard SP primer is a low or mid-level load then the substitution may be deemed "safe” depending on the actual case capacity of the load in question.  How do you know? 

Unless you can measure the pressure, you won’t know.  Dropping back and working back up to the same chronographed velocity is often recommended.  I have even recommended that myself in the past.  But is that safe?  Looking at the velocities of all ten tested primers with the same load we find the average velocities ran from 1171 fps to 1188 fps, a spread of only 17 fps.  Interestingly the lowest and highest velocities of any of the rounds shot were with SR primers.  The average velocity variation falls easily within the average to average variation we can get chronographing the same load several times. 

Thus chronographing really isn’t going to give an indication of the difference in psi.  The three standard SP primers averaged 25,700 psi to 27,900 psi with the highest psi of any individual shot being 31,700 psi.  With the SP magnum primers and the SR primers the psi was always higher with several of the tested shots exceeding the SAAMI MAP of 35,000 psi.  If we ponder what the highest tested shot psi’s would be (not the average of the test) if we had used a max load developed with standard primers in the 34-35,000 psi and then had substituted the standard primer with a SP magnum or SR primer?  The highest shot psi’s would probably have exceeded 40,000 psi.  That would not be what I consider to be "safe”.  Might get away with in in some larger framed revolvers but still not something to be recommended.  In a semi auto you might get away with it but it would beat the gun up at best and if a case head burst at the web.......possibly disasterous.

 LMG