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Build your own: The .32 NAA Browning guns

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By James Frostick, American Handgunner

As trends go toward smaller pistols, and plastic/polymer guns have seemingly taken over the new gun market, I still like the old pocket pistols. They are small, and as their name indicates they fit in your pocket, are usually very thin — and made of steel. These durable little guns have a real-gun feel to them.

I’m no expert here, just a big fan of 1911’s and small semi-auto pistols. Recently I converted two semi-autos into something even better than I imagined. Maybe even better than John Moses Browning could of imagined?

Back in the summer of 2004, while shooting s Kimber 1911 with a Cor-bon 400 replacement barrel (a .40 cal. bullet in a bottle-necked .45 cal. brass case at around 1,300 f.p.s.) something dawned on me. Maybe a .32 bullet in a bottle-necked .380 case would improve ballistics for the small caliber. If I’m going to try and do this, there must be one rule I must follow. Only a simple barrel change is what I’d like to see make it happen. No parts can be changed, or modified, with exception to the barrel and a change of magazine. So easy a novice can do it — maybe?

Deciding on what type of semi-auto to use was easy. I needed a gun made in .32 ACP and .380 ACP. One that was not much problem finding parts for, and because I like 1911‘s, a John Browning designed gun.

Manson supplied a reamer for the .32 NAA and it ended up being an easy conversion,
with just the addition of re-chambered barrels needed


Barrels first?

The first step was to buy .32 ACP Browning barrels, new old stock barrels rather than used. Found four on the web. Then I had what I called a “what came first, the chicken or the egg” moment. I needed a chamber reamer to cut the barrel, and the dies to load the round. But I needed a round to take to the reamer maker to spec the reamer. Uncertain, I put the project on the back burner. Five years later, while talking to a sales person in a Cabela’s ammo department about the conversion idea, he informed me the NAA Guardian shoots similar ammo, made by Cor-bon and it is called the .32 NAA — eureka!

That NAA Guardian web site describes this round as a cartridge/firearm “system” designed and developed by the partnership of North American Arms and Cor-Bon Ammunition. The cartridge is based on a .380 case, which is necked-down to hold a smaller .32 bullet. The result is a remarkable gain in ballistic performance and a new round. It delivers in excess of 1,222 fps in a 60-grain proprietary bullet. When tested in a 4″ barrel it generates 1,453 fps!

The .32 NAA produces more velocity and perhaps more “stopping power” (for a tiny gun) than any conventional jacketed lead hollow point (JHP) .32 ACP, .380 ACP or .380 ACP (+P), and all done with about 15 percent less recoil than the (+P). According to testing, it penetrates 8.3″ of gelatin after passing through four layers of denim, expanding to a .55″ mushroom with a retained weight of 100 percent. I thought this ammo was perfect, it’s not +P ammo and the old guns should cycle the rounds, as-designed, by Browning.

Targeting with the converted guns showed them able to deliver groups in
the 1 ¼” to 1 ½” range in .32 NAA, at ten yards.


The final guns

The Browning M1910 and M1922 have barrels 3.375″ and 4.375 respectfully. Playing with the calculator, using the NAA Guardian’s specifications, ball park numbers would likely be around 1,350 fps from the M1910 and around 1,510 fps in the M1911, both with a 60 grain JHP.

Inspired, I bought a 1910 “shooter” looking like someone threw it down a flight of concrete stairs, but it worked just fine. No more abuse for you little guy, you have a good home now if you survive the operation. I also stumbled onto a nice deal, an elderly five-digit serial number 1922 in .32 ACP that some one took good care of. Browning modified the original pistol to suit requirements of the Yugoslavian military. Browning lengthened the barrel, improved the sites and enlarged the grip and magazine capacity by two rounds. The slide was lengthened, by adding a removable front portion to the model 1910 slide. Both the model 1910 and 1922 were manufactured in large quantities in Europe until 1983.

I ordered the .32 NAA special wildcat reamer, from Dave Manson Precision Reamers. That’s when it sunk in and I realized soon I would get to shoot my idea. I couldn’t wait to feed .32 NAA ammo to my pair of Browning autos! I got the work done — took longer than I had anticipated — and once everything was finished, looked forward to that first day at the range.

James built a custom rest just for these little autos and found it very useful
during testing. Original barrels are on the rest, along with the Manson reamer.
Cor-Bon .32 NAA ammo was used for all the testing.


Did it work?

On a beautiful day at the range with my “new” .32 NAA Browning guns, I was doing the “one round in a magazine” test. I pointed the barrel down-range, pulled the slide back, let it snap forward and the round slid right in. I pulled the slide back again and the round jumped right out. I tried this on both guns with no problems. Ready to fire the gun, I loaded one round into magazine. This time I was feeling a lot of emotions, I was apprehensive and excited and it was a little nerve racking. I pulled the slide back chambering a round, took a breath, let it out and squeezed the trigger. “Ding” — I hit the 6″ plate 25 yards away. I picked up the other gun, loaded one in and dinged the plate again. I shot ten rounds then, saying “Yes!” out-loud after each ding of that plate.

Next, shooting the rebuilds

Later, after shooting a few more rounds, being very relaxed and very encouraged, I bench-rested both guns at 10 yards. The M1910, shooting Winchester .380 ACP 95 gr. FMJ ammo, had a 2″ group. Changing the barrel, the Cor-bon FMJ .32 NAA 71 gr. FMJ, shot a little better at 1 1/2″.

The M1922 was similar, delivering 1 1/2″ group using .32 ACP Winchester 71 gr. FMJ, and after the presto-chango routine, the Cor-bon .32 NAA 71 gr. FMJ grouped around 1 1/4″. I repeated testing both models three times, having similar results each time. Bench resting these small guns is challenging, but I built a small size rest, which proved essential.

The M1910 Browning has little bit of recoil, and the grip shape does not help much. Switching out the magazine to a factory Browning M1971 type, the one with the extended finger hold, is a big improvement. As far as the sights go, the M1910 sights will never snag in your pocket, and it’s a true point and shoot gun. It would be nice if XS Sight Systems would come out with a sight package!

The M1922 is very balanced, and shot tighter groups, with less recoil. The only bug in the gun is the slide-lock, notorious for failing to hold the slide back. I repaired my M1922 with a new Wolf spring and a slide stop made for a 1955 to 1968 M1910.

Presently, I’m working on other .32 NAA conversions, the first being a rare Remington model 51. It’s the gun history left behind. I will try and help give it a little notoriety and the lightning fast round it deserves. And there are a few more pistols I’m going to try a .32 NAA conversion on. A Mauser HSc, Colt Model N/M, Browning 1971 target model and the M1903/07 Browning are all waiting patiently for their turns.

James found that powering-up these old pocket-autos was easy and fun.
He now plans on converting a Remington Model 51 among others. He says,
“Give it a try!”


Should you do it?

The .32 NAA is a very fast, accurate round, turning these guns into Browning Pocket Rocket Pistols. The M1910 or M1922, in either .32 or .380 ACP can be converted. This happens only if both models use the same extractor, ejector and breech face. I used the .32 cal. magazine that came with the M1922 for all testing. I did have it jam twice using the .32 NAA ammo. As a rule, all .380 Browning or F&N factory magazines will feed flawlessly.

Here’s a few costs. A .32 ACP Browning barrel will cost under $75. A reamer is $179, ammo is about $25 for 50 rounds of 71 gr. FMJ, and 60 gr. JHP are about $1.00 each. I spent a total for the test guns of around $550. You will have to work out a price for reaming the barrels, unless you have the talent to do it.

If you are thinking about a small semi-auto — and I can’t stop doing just that — you just might consider finding an original pocket pistol and handing it some big .32 NAA attitude!

Thanks to our friends at – get American Handgunner delivered to your home for $9.95 a year, click here.

(Special thanks to: Dave of Dave Manson Precision Reamers, 8200 Embury Rd. Grand Blanc, MI. 48439, (810) 953 0732, Thomas Sobeck of TWS antiques S. 55th Ave. Oak Lawn, IL. 60453, Chicago Heights Loyal Order of the Moose Lodge 828 Gun Club)

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