M1 Carbine Primers

[usmc69]

What do you use for a primer in the M1 Carbine? I know Small Rifle Primers are preferred. But will Small Pistol Primers work in the carbine? Just want to make up some plinking loads.

[Larry Gibson]

Best to stick with SR primers given the floating firing pin.

[bimus]

I tried a few years ago with Federal small pistol primers with Winchester 296 powder my regular load with a cast bullet is just over 1825 FPS they would really flatten the primer . I started working down and when I got to about 1600 FPS the primer was much better at taking the pressure .

The 30 carbine is a high pressure round and Winchester 296 powder seams to be very sensitive to how deep the bullet is seated .
I have also used Unique powder to make loads for the kids it won't work the action and they really liked shooting .

[35 Whelen]

I use whatever fits the primer pocket that I happen to have the most of sitting on the bench. A few weeks ago I tested several different primers in my Quality Hardware .30 Carbine. I thought I posted the results in a thread here, but maybe not. So here's a copy and paste of the test-

Rifle- Garden variety post war rebuild Quality Hardware M1 Carbine 8/43 production with an 18" Rockola barrel.



Components-
Case- LC 71
Powder- 14.8 gr. Ramshot Enforcer (AA4100)
Bullet- Armscor 110 gr. FMJ

Cartridge o.a.l.- 1.660"

Fiocchi SPP- 1952 fps, 11 fps ES
CCI500 SPP- 1964 fps, 20 fps ES
CCI550 SPMP - 1993 fps, 12 fps ES
Rem 6 1/2 SRP- 1992 fps,18 fps ES
CCI400 SRP- 1984 fps, 56 fps ES
CCI450 SRMP- 1978 fps, 53 fps ES
Wolf SRMP- 1971 fps, 58 fps ES

As one can see, there's no appreciable difference in velocity between the primers. I think this would tell us that the pressure differences are also very small with no particular primer standing out as adding to or reducing pressure. (As a side note, the Fiocchi SP has been my go-to for .38 Special practice loads and it yielded lower velocities than other primers in that cartridge too)
If you're a math nerd, the average velocity of all the different primers was 1976 fps and the extreme spread between the slowest and fastest was only 41 fps. Going from memory, the extreme spread between the lowest and highest individual rounds was about 65 fps.

I know that many who reload the .30 Carbine use H110/W296, so tomorrow I plan to repeat the same test only I'll use 15.0 gr. of W296.

Components-
Case- LC 72
Powder- 15.0 gr. of W296 (H110)
Bullet- Armscor 110 gr. FMJ

Cartridge o.a.l.- 1.660"

Fiocchi SPP- 1934 fps, 69 fps ES
CCI500 SPP- 1960 fps, 69 fps ES
CCI550 SPMP - 1973 fps, 62 fps ES
Rem 6 1/2 SRP- 1976 fps, 39 fps ES
CCI400 SRP- 1993 fps, 23 fps ES
CCI450 SRMP- 1967 fps, 41 fps ES
Wolf SRMP- 2004 fps, 54 fps ES

Again, there's no appreciable difference in velocity between the primers. One thing that caught my attention was the CCI450's which are SRM primers. With both powders these primers gave lower velocities than their standard counterparts, the CCI400. My CCI450's were quite a bit older than the CCI400, I'd say probably '80's vintage, so I wonder if this is why the velocity with them was lower. For some reason the Wolf SRM's really kicked it in the butt and gave the highest velocities, averaging over 2000 fps. The Fiocchi SPP's again yielded the lowest velocity.

For you math nerds the average velocity of all the primers with W296 powder was 1972 fps with and extreme spread of 70 fps.

It's interesting that the extreme spreads were overall lower with Ramshot Enforcer powder. I really like this powder and will probably use it exclusively from now on. Also I failed to mention that none of these charges with either powder were weighed, they were all thrown directly from an RCBS Uniflow. I checked several charges during the process and every time, they were spot-on.

35W

[Larry Gibson]

"As one can see, there's no appreciable difference in velocity between the primers. I think this would tell us that the pressure differences are also very small with no particular primer standing out as adding to or reducing pressure."

That is an assumption I once believed also. However, actual testing proved using a chronograph to assume pressures are the same with a switch of primers proved to be a false assumption. The same can hold true when switching powders. Don't assume the pressure is "safe" because the velocities are relatively the same. Here's a test of different primers I ran with the 357 magnum:

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.

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.

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 disastrous.

In the 9mm P with its much smaller case capacity? I would not use any other primer than a standard SP primer with other than a "starting load".

[dale2242]

If you have a choice, use the SR primers.

[racepres]

Do Not use Rem 6-1/2 for high pressure loads... even Remington tells us ...Hornet type loads Only...
After I had more than my share of Blown primers... Years ago... before said warning.. they blow holes at corner... Not at firing pin!!!!

[barnetmill]

Do Not use Rem 6-1/2 for high pressure loads... even Remington tells us ...Hornet type loads Only...
After I had more than my share of Blown primers... Years ago... before said warning.. they blow holes at corner... Not at firing pin!!!!

Was this for 30 US M1 carbine. I know it should not be used in the 5.56/.223 that is a high pressure round. I had read that the 6 1/2 was a close duplicate for the original government loading and I seldom use the max load when reloading cartridges.

Here is an old thread on primers and 30 us carbine https://castboolits.gunloads.com/sho...arbine-primers

[usmc69]

Thanks for the information. My problem is that I have 16,000 small pistol primers and no small rifle primers on hand. Guess that I will have to get some small rifle primers.

[racepres]

Thanks for the information. My problem is that I have 16,000 small pistol primers and no small rifle primers on hand. Guess that I will have to get some small rifle primers.

If I were you... I go By the Specs... Far as I know or have Researched.. Magnum small pistol primers are the same cup, as small rifle Primers.. the charge??? IDK I know the cup is Very thin on rem 6-1/2's...and only use them for Hornet, cast 222 and Cast Pistol...if the Hammer strike will reliably set them off... which is Not the case with "gunsmithed" S&W's for one...

Edit: I found my primer Chart.
small Pistol primers are generally a .017 thickness Cup. wether for Standard or Magnum loads.
Small rifle standard are generally a .025 cup... except the WSR at .021 and the Rem 6-1/2 as well as CCI-400's!!! at .020..CCI claims the 400's best for Hornet and 30 M1, just like rem 6-1/2's..
On bottom of the page CCI says; CCI - 550's and CCI - 400's are the same primer..
add salt... Shake!!

[35 Whelen]

Do Not use Rem 6-1/2 for high pressure loads... even Remington tells us ...Hornet type loads Only...
After I had more than my share of Blown primers... Years ago... before said warning.. they blow holes at corner... Not at firing pin!!!!

Remington 6 1/2 primers, as I understand it, are for use in the .22 Hornet and .30 Carbine. I bought a couple thousand primers from Jeff Bartlett that came from pull-down Lake City .30 Carbine ammunition. Other than being a bit dull, they look very much like Remington 6 1/2 primers.

Mr. Gibson thank you for posting your test, I found it very interesting and greatly appreciate the efforts you put forth!

Unfortunately most of us don't have pressure testing equipment so we either guess, or rely on our chronographs. I'd rather not guess. Since the .30 Carbine is considered a rifle cartridge, and reloading manuals instruct us to use rifle primers when loading it, the true purpose of my test was to see if there was any real difference in rifle primers and pistol primers in said cartridge. I don't see enough difference to matter, at least for my use, as using pistol primers resulted in velocities within a few fps of rifle primers and in some cases the velocities attained with pistol primers exceeded those attained with rifle primers. Since small pistol primers are used in the .327 Federal Magnum and it is loaded to higher pressures (45,000 psi) than the .30 Carbine (40,000 psi) logic would dictate that the use of SPP's would be fine in the .30 Carbine.
I think the line between what constitutes a pistol cartridge and what constitutes a rifle cartridges are somewhat blurred. I don't think anyone would argue that the .30 Carbine is as much, if not more of a pistol cartridge than a rifle cartridge. So when one loads shells for their Blackhawk .30 Carbine, should they use pistol primers?

35W

[Larry Gibson]

If I were you... I go By the Specs... Far as I know or have Researched.. Magnum small pistol primers are the same cup, as small rifle Primers.. the charge??? IDK I know the cup is Very thin on rem 6-1/2's...and only use them for Hornet, cast 222 and Cast Pistol...if the Hammer strike will reliably set them off... which is Not the case with "gunsmithed" S&W's for one...

Edit: I found my primer Chart.
small Pistol primers are generally a .017 thickness Cup. wether for Standard or Magnum loads.
Small rifle standard are generally a .025 cup... except the WSR at .021 and the Rem 6-1/2 as well as CCI-400's!!! at .020..CCI claims the 400's best for Hornet and 30 M1, just like rem 6-1/2's..
On bottom of the page CCI says; CCI - 550's and CCI - 400's are the same primer..
add salt... Shake!!

The thickness of the cup is a major consideration in the M1 Carbine because of the floating firing pin as mentioned previously. However, it is the primer compound difference between SP, SPM and SR/SRM primers that makes the difference in the actual psi generated. The compounds used in standard SP and SR primers are not the same as the primer compounds used in magnum SP and SR primers. The CCI 400 and 550s being the exceptions.

[Larry Gibson]

35 Whelen

I also appreciated you well done test and the presentation of the complete data. However, my post (#5) was not in reference to the topic of this thread but was in deference to your statement; "I think this would tell us that the pressure differences are also very small". While substituting primers in small cases using very fast burning powders, the data I presented clearly shows the statement does not apply to slower burning powers. Some SP magnum, SR and SRM primers can, indeed raise pressures significantly while the chronographed data does not indicate that.

Note that the Remington 6 1/2 primer is a SR primer with a thicker cup than SP primers. The crux of my first post (#2) was to prevent potential slam fires in the M1 Carbine by the use of the thinner cupped SP primers.

[LabGuy]

Thanks for the information. My problem is that I have 16,000 small pistol primers and no small rifle primers on hand. Guess that I will have to get some small rifle primers.

USMC69, if your going to be around Tallahassee, I could swap you 1K to get you going.

[usmc69]

USMC69, if your going to be around Tallahassee, I could swap you 1K to get you going.

Thanks for the offer, but that is a one way 5 1/2 hour drive. Got some from a friend here.