Tuesday, September 6, 2011

A Look at the .32 ACP and .32 NAA

Back in the early 1990's, when someone mentioned a mouse gun, my immediate thought went to the Walther TPH, Seecamp LWS32, or Taurus PT-22.  These tiny vest pocket sized guns were usually offered in .22, .25, and .32 calibers.  I always wanted a Seecamp, but this was pre-internet boom and I had no idea how to track down a local dealer so I could get on the 1 year plus waiting list for one.  I did have a Taurus PT-22 for a few months, but it was very unreliable in feeding and firing.  By the end of the 90's I had one small gun left in my collection.  A stainless and alloy framed Colt Mustang Pocket-lite .380.  I didn't pay much attention to mouse guns at all from 1998 to about 2007.

Here's a quick picture comparing the rounds discussed in this blog entry.  From left to right we have:

 .22 Long Rifle
.32 ACP HP
.32 NAA HP
.380 ACP

I'm really not 100% clear on how I stumbled on the Seecamp website, but one day I found myself there and clicked through to their Seecamp owners forum.  I started catching up on all the old posts and found myself getting sucked back into the quest for a Seecamp of my very own.  I also started reading up on all the new mouse guns that had come out over the previous 12 years and all the new makers and models available.  A few old models like the Colt Mustang and Walther TPH were now gone, but for every model that was discontinued, there were many more to take it's place.

Prior to getting my Seecamp LWS32, I had never seen a .32 ACP cartridge.  In my small world, pistol ammo came in .22 LR with the next step up being .380 ACP.  While I was shooting my Seecamp, I came to understand and appreciate the .32 ACP for what it had been in the past and where it fit in our current times.  According to what I've read the .32 ACP cartridge was designed by John Moses Browning and commercially released in 1899.  Through the last century the cartridge has been used by police forces and civilians.  The concealed carry trend gave the .32 ACP a lift in popularity in recent years with several new lightweight pocket sized pistols coming on the market.

I recently had an opportunity to do some data gathering on the .32 ACP.  Along the way, what started as a simple exercise to chronograph some different rounds from a Kel-Tec P-32, grew into something much bigger so this blog entry is really the culmination of several months of activity.  It may seem scattered, but the common thread is the .32 ACP cartridge.

Initially the plan was to do a .32 ACP ammo study similar to the .380 ACP study from July.  While I was running my initial tests with a Kel-Tec P-32, I got word that Bersa was putting out a limited number of their Thunder models in .32 ACP.  Having recently rediscovered Bersas, I decided I should get my hands on one and include it with the Kel-Tec testing.  It's really a fantastic little firearm.  Aside from the obvious good looks, it come with windage adjustable sights and a factory 10 round magazine that brings the capacity to 11 rounds of .32 ACP in a convenient sized carry package.  It's been a reliable feeder of anything it's been fed, delivers reasonable accuracy, and it's a joy to shoot with very little recoil. 

The Kel-Tec P-32, I've had for some time now.  It's the lightest pistol I have ever had my hands on.  It holds 7 rounds in the flush fitting magazine for a total capacity of 8 rounds and weighs in at 10.3 ounces fully loaded. It lacks target type sights, but the rudimentary sights milled into the slide are satisfactory for it's intended purpose.

Rapid fire at 7 yards on 5" pie plates, really demonstrates the value of the .32 ACP cartridge.  With some practice and attention to trigger technique, it's quite possible to put rounds on target quickly since you have less muzzle flip and recoil to counteract after each shot.  A Bersa grouping is shown on the left and a Kel-Tec grouping is shown on the right.  

I've mentioned the Seecamp LWS32 earlier in the blog.  I did not include the Seecamp in my testing for two reasons.  The first is that it comes with NO sights.  "Aiming" is accomplished by practicing a technique called point shooting.  Since I was running rounds over my chronograph, I didn't want to risk an errant shot putting my sky screens out of business.  The second reason is that the Seecamp was designed around one specific cartridge, the Winchester Silver Tip.  I will get into that a bit more later in the blog.

Have you ever read about the new .32 cartridge that was developed by North American Arms and Cor Bon?  Dubbed the .32 NAA, the cartridge is made by necking down a .380 ACP case to accept the .32 bullet.  Very recently, the folks at Diamondback Firearms released their DB 320.  The DB 320 uses all the same parts as the DB 380 except for a barrel that is bored and chambered for the .32 NAA cartridge.  If you own a DB 380, you can purchase a .32 NAA barrel and instantly convert your pistol to use the new round.  Switching back is as simple as removing the .32 NAA barrel and reinstalling your .380 ACP barrel.  It's like having two guns in one.  Since I was testing and reporting on .32 ACP, I thought I would also test out the .32 NAA while I was at it.  The photo below shows the .32 NAA barrel installed in a DB 380.  The .380 ACP barrel is shown resting on the frame of the pistol for illustrative purposes.

The spreadsheet below has all the chronograph results from my testing.  Click on the picture to bring up a larger version of the sheet that is actually legible.  As expected, the Bersa's longer barrel gave every round the chance to build up greater velocity and energy.  Three varieties of ammo were not tested in the Bersa because I used up all the rounds breaking in the Bersa a few weeks ago.  I did have several varieties on hand for comparative testing.

If spreadsheets aren't your thing, I plotted the data on the charts below.  The charts show the comparative energy of each round and are listed from highest to lowest.  The big surprise for me was the Corbon loading.  Corbon's claim to fame is high velocity rounds that are loaded within industry specifications for pressure.  Their tested round was defiantly the highest velocity and highest energy round in the test.  Sellier and Bellot's 73 grain FMJ offering was the fastest and highest energy loading of that type.

I also found it interesting that Fiocchi loads their Extrema round with Hornady's XTP bullet to a much higher velocity than Hornady does in their own Custom line of ammunition.    

My results with the two .32 NAA rounds through the Diamondback conversion barrel left me a bit mystified.  To my knowledge, only Corbon offers .32 NAA ammunition so that's all I could get my hands on.  When comparing the fastest .32 ACP FMJ load through the Kel-Tec P-32 against the Corbon .32 NAA FMJ load, there is an obvious velocity increase and energy gain even though the .32 NAA bullet is a couple grains lighter.  Corbon advertises 1000fps velocity from their FMJ load, which was realized today on my chronograph.  The confusing part for me was their 60 grain HP load falling well short of their 1200fps advertised velocity.  The velocity improvement over their .32 ACP load in the Kel-Tec P-32 is so slight that I will say it's just down right disappointing and not worth the cost of proprietary ammo.

I will add that the Corbon .32 NAA HP load was incredibly soft shooting.  It felt much more like shooting a rim fire pistol than a center fire pistol.  Perhaps they had a batch go out with light charges and that's the lot I received.  

My DB 380 is the discontinued MS (milled sights) version.  The sights are milled directly into the slide so my accuracy isn't as good as it would be with a pistol that has target sights.  I would say the sights are very similar to those on the Kel-Tec P-32.  The target below shows two groups of 7 rounds each of the .32 NAA FMJ loading.  The target on the right is 7 rounds of the .32 NAA HP load.  The reduced recoil of the HP load is demonstrated by the reduced vertical stringing of my shots.  I'd like to say there are 7 holes on the right target, but I can only count 6.  I must have shanked one shot.

There is one more advantage of the .32 NAA over the .32 ACP.  The .32 ACP is a semi-rimmed cartridge.  Semi rimmed cartridges work best in revolvers where the rim helps prevent the cartridge from slipping into the revolver cylinder.  When semi-rimmed cartridges are held in a pistol magazine, they can shift forward and backward during the firing, recoil, and loading processes in such a way where the cartridge rims will get locked together and render the pistol incapable of feeding another round into the chamber.  This condition is called Rim Lock.  Since the .380 ACP is a rimless case, and that's the basis for the .32 NAA cartridge, rim lock is not an issue.

Up above in my initial spreadsheet you may have noticed a column called OAL.  OAL is an abbreviation for the cartridge Over All Length.  You can measure it with a dial or veneer caliper, which I have done for the rounds I had on hand.  In the chart below you can see that current production ammo falls roughly into two size groups.  The first is rounds measuring .910" or less.  The rounds have bullets with flat or hollow point noses.  Earlier I mentioned that the Seecamp was designed around the Winchester Silver Tip round.  Seecamp gets around the rim lock issue by installing a filler in the back of their magazines that keeps rounds longer than .910" from fitting in their magazines.  With less front to back room for rounds in the magazine to slide, the opportunity for cartridge rims to "lock" together is minimized.  I'd like to say eliminated in place of minimized, but one never knows for sure.  Kel-Tec offers a similar rim lock prevention device for their magazines.  Rounds longer than .960" are less prone to rim lock in standard .32 ACP magazines because they fill the front to back space within the magazine and therefore do not slide during firing.  Rim lock is again minimized.  There are a couple of rounds that fall in the no man's land between .910" and .960", while I did not experience rim lock with either round, it would be wise to test these rounds extensively in your specific pistol and magazines before putting them into service.  I've only experienced rim lock on one occasion and that was at the practice range before I installed the rim lock prevention kit in my Kel-Tec magazine.  If you ever experience rim lock, you will never want to experience it again.

Ideally, I would also include some terminal ballistics data with this entry.  Unfortunately, I'm still working on my bullet trap.  It's been a long design and development process, but I'm getting closer to the end goal every week.  I did manage to catch a couple .32 ACP bullets over the last month.  I wanted to test them all, but I keep destroying my prototype traps.

My first "catch" was a Speer Gold Dot .32 ACP that was fired through 2 layers of denim and it penetrated through my entire catch box before coming to rest in a water jug I had backing my catch box.  No noticeable expansion versus the unfired round on the left.

My second catch was a Corbon 60 grain .32 ACP.  This round penetrated through 2 layers of denim and 16.5" inches of media in my catch box before coming to rest.  Expansion was excellent.

If you've stuck with me to the end here, I hope you enjoyed the post and possibly even got an idea or two from it.  The .32 ACP may be 112 years old now, and while other cartridges of similar age may be gone into obscurity, this little guy keeps right on rolling along.  There are some very small and light pistols available for the cartridge and it's lighter recoil may appeal to those that find larger cartridges to be too punishing.

As far as the .32 NAA goes, it's a new guy on the block that was supposed to deliver performance greater than the .380 ACP (according to Wikipedia).  From my limited testing, I don't find that to be the case, but I'm keeping an open mind for the moment.  Perhaps I just got some bad boxes of Cor Bon HP ammo.  Regardless, anytime I can get a conversion barrel for a pistol I currently own, I'm a happy man.  Maybe I'll do a blog about conversions one day.