9mm Winchester Magnum

By Ellis

      A few years ago, I had the opportunity to do some hand loading for an AMT Automag III chambered in 9mm Winchester Magnum (9x29). It was a really fun project that took me to a very experimental place for a hand loader. At the time, no factory ammo was made for this caliber and there was an incredibly small amount of data for reloading.

     There have been a ton of 9mm cartridges designed for auto loaders over the years. 9x18 Makarov and 9x19 Luger, come to mind as the most popular. There are some others that are historic or primarily used in competition like 9x23 and 9x21. Recently, 9mm Major has gained popularity in competition shooting but it’s essentially a 9mm Luger operating at the limits of its design to reach ‘major power factor’ for USPSA/IPSC. 9mm Magnum is an entirely different beast. It was developed in the 70s to get .357 Magnum performance out of an autoloading pistol. You can see a standard 9mm round in the first picture for scale.

     For this project I used my Lee press, RCBS dies, Starline brass, Accurate No. 9 powder, and Hornady projectiles. The brass is still made mostly for 9mm blanks because the increased length allows it to be easily crimped. Due to the high speed of 9mm Magnum, Berry’s plated bullets will not hold together, that is why a true FMJ from Hornady was used. I loaded to approximately 1.51 OAL and I crimped to .378 to pass the plunk test.

      As one should always do, I started on the low end of my powder load. Using some data I found that used similar components, I tested a few loads as well as some other questionable handloads the owner had that were made previously. I worked the load up in speed and finally settled on 13.7gr of powder, which chronoed in the mid-1500s FPS.

      Shooting the Automag III was a lot of fun. Due to the large size of the pistol, recoil wasn’t bad, even when projecting some 147gr bullets. The fastest load I shot was 1696 FPS. That is some serious energy! If two people are ever debating the efficacy of 9mm Luger over .45ACP, just bring up 9mm Magnum to stir the pot, watch out though, they may trump you with .45 Win Mag.


9mm Magnum (9x29)

Load Data


Hornady 115gr FMJ-RN (.355)


Accurate No. 9 (13.7 gr)


Federal Small Magnum Pistol Match (GM200M)


Starline Brass




1564 fps at 80°




Component Cost Estimate (2021 prices)



Cost with tax












$208.50 est

Total Cost for Components




Per Round Cost

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