32 ACP Factory Pressures

[Larry Gibson]

I recently, in collaboration with Outpost75 who supplied most of the factory loads, completed a rather extensive testing of twelve 32 ACP factory loads and selected reloads. Testing was delayed until the temperatures here in the desert got down to 65 t0 80 degrees. The test barrel was a Contender 10” barrel chambered in 32 H&R. The 32 ACPs fired fine in that chamber. The pressures were measured via a strain gauge located at the SAAMI specified location over the chamber. The Oehler M43 PBL was used. All except one test recorded 10 measurements as per SAAMI standards of testing.

319401

Given the longer 32 H&R chamber the recorded pressures measured we could assume the recorded pressures would be somewhat less than actual pressures. However, given the consistency of the internal data measurements and the measured pressures the longer chamber didn’t appear to give much less pressure readings. The SAAMI MAP for the 32 ACP is 20,500 psi with one of the tested factory loads exceeding that. The European [Nine of the tested loads were of European manufacture] CIP MAP is 1600 Bar (23,206 psi) with none of the tested lads exceeding that. Thus, the testing of the twelve factory loads was to establish a base line pressure range to use as “reference” when developing maximum loads.

This data of the twelve factory 32 ACP/7.65 Browning cartridges is presented for reference only. I list the factory load, weight of the factory powder charge, the pressure of that load and the velocity out of the 10” barrel.

319402

Federal 71 gr FMJ………2.7 gr………12,600 spi……..748 fps

Winchester 71 gr FMJ…..1.8 gr…...12,800 psi…….595 fps

Western 71 gr Lubaloy…..2.0 gr…...14,200 psi…….795 fps

PL M76/FN 71 gr FMJ…..1.8 gr…...14,200 psi……827 fps

Fiocchi 73 gr FMJ…..1.8 gr………..14,300 psi…….892 fps

Norma 77 gr FMJ……1.6 gr……..15,100 psi……..776 fps

Sellier & Bellot 73.5 gr FMJ…….2.5 gr…..15,300 psi……938 fps

GECO 71 gr FMJ……2.0 gr……15,800 psi…….841 fps

RWS 73.5 gr FMJ…….3.3 gr…….16,100 psi………973 fps

RWS 77 gr FMJ……..1.6 gr……..17,200 psi…….989 fps

Sellier & Bellot NP 3983 71 gr FMJ ……2.3 gr……18,500 psi……891 fps

Hertenberg 71 gr FMJ……3.0 gr …….21,600 psi…….989 fps

Note the two current US factory loads [Federal and Winchester] were much lower in performance than any of the European factory loads. The older Western Lubaloy load was at the bottom end of European performance.

Again, data is presented for information and reference only.

Many thanks to Outpost75.

[rintinglen]

Thank you both. Very useful info that goes a long way to explaining the generally poor performance of the 32 ACP in US ammo.

[alfadan]

Dang, if I'd known I could have donated some prvi partisan for testing. Thanks for the data.

[ohen cepel]

Thanks for that! Always thought/heard that the EU stuff was hotter but this proves it.

[billmc2]

Larry, I have no idea as to how any of that gear works. I thought I read another post you made, not long ago, which said that the actual pressures between SAAMI and CIP were the same, the difference between the two arose from the location of the pressure sensor. Did I get that right or am I misremembering?

As to the results, thank you. I find it a little curious that none of the pressures you measured were anywhere near the maximum. Because I don't know, I'll ask is that normal?

[Larry Gibson]

Larry, I have no idea as to how any of that gear works. I thought I read another post you made, not long ago, which said that the actual pressures between SAAMI and CIP were the same, the difference between the two arose from the location of the pressure sensor. Did I get that right or am I misremembering?

As to the results, thank you. I find it a little curious that none of the pressures you measured were anywhere near the maximum. Because I don't know, I'll ask is that normal?

The actual average pressure of a given cartridge will essentially be the same regardless of how it is pressure tested because the loaded cartridges are what they are. Some differences in test barrels can have a small effect, however, as test to test variation can also give some slight variation. It is the difference using piezo transducers between the method SAAMI uses and the method that CIP uses to measure that pressure which creates a different average pressure number [MAP for SAAMI, Pmax for CIP] that causes some confusion.

Let's look at the 308W for example; SAAMI and CIP both list the CUP pressure method of a SAAMI MAP of 52,000 and a CIP Pmax of 52,000, essentially the same because the measuring method is essentially the same. For Piezo transducer pressure measurement SAAMI gives a MAP of 62,000 psi while CIP gives a Pmax of 60,000 psi. The difference is simply that SAAMI places the transducer over the center of the case volume area and CIP places the transducer at the case mouth. In this instance the listed MAP is larger than the listed Pmax. That is not always the case. Some cartridges will have a higher SAMMI MAP than the CIP Pmax.

Other cartridges will have a higher CIP Pmax because European CIP allows a higher Pmax for those cartridges. The 6.5x55, 303 Brit and the 8x57 Mauser are examples. The 6.5x55 has a MAP of 51,000 psi and a Pmax of 55,000 psi. The 303 Brit has a MAP of 49,000 psi and a Pmax of 53,000 psi. The 8x57 Mauser has a MAP of 35,000 psi and a Pmax of 57,000 psi. Those three cartridges, plus numerous others, can be loaded to a higher MAP/Pmax under European CIP standards.

Actually, the Hertenberg 32 ACP factory ammunition with an average psi measured at 21,600 exceeded the SAAMI MAP for the 32 ACP of 20,500 psi. Yes, it is mostly normal for factory ammunition to be under the MAP or Pmax. This is especially the case with older cartridge for which there are older firearm designs that may be of questionable strength. Additionally, not have an actual reference load of known pressure to use as a measurement/"calibration" it is hard to guestimate the actual effect firing the cartridges in the slightly long 32 H&R chamber had on the data.

The data presented was not meant to be an absolute correct measurement of the pressures but simple a comparison of the difference between the various different makes.

[shooting on a shoestring]

Larry and Outpost, nicely done!
That’s some interesting data y’all generated. I especially appreciate that you included the factory charge weights.
Your pressure data comparisons and velocity comparisons are very much appreciated and enlightening!
Thanks for putting your equipment, ammo collection and effort into this project. That was certainly a bunch of data collection and record keeping work.
THANK YOU!

[pworley1]

Thank you for sharing this.

[Larry Gibson]

Dang, if I'd known I could have donated some prvi partisan for testing. Thanks for the data.

PM me if you want to send some factory 32 ACP to test. I can always run a test next time I set up for pistol cartridge testing and add the info to the data base for the 32 ACP.

Anyone else have any other factory 32 ACP loads you'd like to donate?

As to the specific reloads tested I sent the data to Outpost75 as the testing of those was at his request. He can post the results if he wishes along with the reasons for the loads. There were some useful loads. I'm also going to do a little more testing with 84 gr bullets [313249s] loaded over Bullseye, 700X, 231, Red Dot and TiteGroup with the goal of pushing the loads up into the 18,000 psi range. I'll post that data in the future.

I don't even have a 32 ACP pistol yet, so all my testing is just in the Contender test barrel.

[racepres]

Great stuff...and Greatly appreciated... Now, Rightly or Wrongly. I sure would be able to appreciate the FPS of a couple of these loadings in an Appropriate for Ctg Chambered Firearm.. just as a reference, as I believe that Knowing that (A) ammo is closer to the High Pressure end, produces (X) velocity. If My Reloaded (B) ammo produces that or Higher FPS.... My Pressure are approaching the High End..Probably...
Not very scientific...But, I have Never assumed that I might have a Firearm that, Magically, makes More FPS with Less Pressure... Just something on my mind...Certainly No shadow of Belittlement on that which is Provided..As I suspect plenty of Folks are running ACP, thru their H&RMag...whilst running ACP in an S&W Long is perhaps Bad Practice..
Thank You Gentleman

[FergusonTO35]

Thanks so much for posting this. My chronograph has always shown just how watered down USA .32 Auto is. Would be interesting to do the same test on .25 Auto, I bet many loads don't even make 10k.

[billmc2]

Larry, thanks for the explanation.

[Outpost75]

FYI .32 ACP velocity data for factory loads fired in my 1944 manufacture Beretta Model 1935 with 9cm barrel:

W-W 71 FMJ 847 fps, 33 Sd
R-P 71 FMJ 877 fps, 15 Sd
Fed 71 FMJ 866 fps, 15 Sd
Fiocchi 73 FMJ 892 fps, 21 Sd
Geco 73 FMJ 938 fps, 19 Sd
RWS 73 FMJ 973 fps, 31 Sd

Rem. 93 FMJ (.30 Luger bullet) 3 grs. AutoComp Starline case R6-1/2 pmr, OAL 0.97" - 933 fps, 22Sd, Larry measured 21,200 psi. Do Not Exceed.

[racepres]

FYI .32 ACP velocity data for factory loads fired in my 1944 manufacture Beretta Model 1935 with 9cm barrel:

W-W 71 FMJ 847 fps, 33 Sd
R-P 71 FMJ 877 fps, 15 Sd
Fed 71 FMJ 866 fps, 15 Sd
Fiocchi 73 FMJ 892 fps, 21 Sd
Geco 73 FMJ 938 fps, 19 Sd
RWS 73 FMJ 973 fps, 31 Sd

Rem. 93 FMJ (.30 Luger bullet) 3 grs. AutoComp Starline case R6-1/2 pmr, OAL 0.97" - 933 fps, 22Sd, Larry measured 21,200 psi. Do Not Exceed.

That helps me in my Curiosity..Thank you Very Much Indeed!!

[P Flados]

Thanks again to Larry & Outpost75. Real data trumps conjecture by a country mile.

[pettypace]

FYI .32 ACP velocity data for factory loads fired in my 1944 manufacture Beretta Model 1935 with 9cm barrel:

W-W 71 FMJ 847 fps, 33 Sd
R-P 71 FMJ 877 fps, 15 Sd
Fed 71 FMJ 866 fps, 15 Sd
Fiocchi 73 FMJ 892 fps, 21 Sd
Geco 73 FMJ 938 fps, 19 Sd
RWS 73 FMJ 973 fps, 31 Sd

Rem. 93 FMJ (.30 Luger bullet) 3 grs. AutoComp Starline case R6-1/2 pmr, OAL 0.97" - 933 fps, 22Sd, Larry measured 21,200 psi. Do Not Exceed.

Your reload that got my attention was the heavy XTP at something north of 900 f/s. IIRC that load expanded to about 0.40" in water and had a predicted wound mass (by MacPherson's calculation) equivalent to .45 hardball!

Was that load pressure tested? From the 93 grain FMJ data above, I'm guessing it would be a bit strong?

[uscra112]

Very informative. Thank you. I have only one .32 ACP pistol, an old Ortgies that has a slightly rough chamber. It often fails to cycle with Federal and Magtech ammo. Guess I need to try some European brands.

[Outpost75]

Larry did not test the 90-grain XTP, but I expect that results with that bullet and 3 grains Autocomp would be similar to the tested load with the Remington .30 Luger 93 FMJ bullet. FYI 3 grains of Unique with the 93 FMJ was also satisfactory and did not exceed the CIP Pmax, although it does slightly exceed the SAAMI MAP.

I would not use either the 3 grain AutoComp.or 3 grain Unique loads with the .312" diameter 100 XTP. They could be used with the 85 XTP only if barrel groove diameter exceeds .311". Otherwise stay with the .309" diameter 90-grain XTP.

[onelight]

Thanks for the testing and information guys .
Very informative .

[reddog81]

Thanks for the info. I figured there'd be some variation but that is quite the spread. Any ideas why the American ammo is so weak? When I think of old .32 ACP guns the first thing to come to mind is the Colt Pocket Hammerless and Savage 1907 which I believe are fairly robust guns (robust for .32 ACP at least...).

[Kosh75287]

I am not equipped to measure chamber pressures, but the findings of Larry Gibson and Outpost 75 are entirely consistent with my "suppositions" about U.S. made ammunition, vs. that available from the E.U. Based solely, and not very scientifically, on slide velocity/ejection distance plus a few stints behind chronographs, the European fodder always seems at least slightly hotter, and sometimes by a considerable margin.
The differences were most apparent to me in .32 & .380 ACP, and 9mm Parabellum, but I've detected a slight performance edge with .357 Magnum .45 Colt, and various U.S. rifle calibers made in Europe. The 8x57 Mauser is obviously a non-example, since U.S. manufacturers are constrained to use the attenuated SAAMI M.A.P. for the round, while European manufacturers may load it to half-again higher pressures.

[FergusonTO35]

The .32 and .380 Auto were used for decades in Europe as police and military rounds so it's not surprising that they would be more particular about keeping velocity up. I use a Makarov equivalent load in my Glock 42's and have no doubt it would be quite effective, at least within the possible envelope for that gun and cartridge.