Many of us have heard of the detachable magazine conversion kit sold by Legacy sports and Weatherby. This replaces the original bottom metal with a polymer bottom that accepts proprietary magazines sold by Legacy Sports.
For less than 100 bucks you can do this drop-in conversion, and it includes either a 5 round or a 10 round magazine. Extra magazines are around 40 bucks. Legacy Sports conversion
Many have commented that the plastic replacement for the trigger-guard and bottom metal is less than delightful, and wish it were made of metal instead. There are also comments stating that standard AR magazines would be much preferable to the proprietary ones offered by Legacy Sports.
Pacific Tool and Gauge makes a DM conversion kit for the SA Howa that features a trigger guard/bottom metal made of CNC milled aluminum, finished in black. 308 magazines are metal, the 223 magazine offered is polymer. These cost about 50 bucks more than the Legacy Sports conversion. They share the drawback of requiring proprietary magazines though. PTG conversion
I was on the phone with PTG today, and was informed that a new DM conversion for the Howa action is in the works that will accept standard AR magazines, but that there is no firm date on when it will be on the market.
In the mean-time, the PTG conversion with real metal on the bottom metal seems like the best current alternative. They want 158.00 bucks for the model with the 10-round .223 polymer magazine.
I have decided to skip the plastic Legacy Sports conversion and go with the metal PTG model instead - but now I'm thinking that it might be smartest to wait until the version that takes standard AR magazines comes out.
FYI: I was just looking at Howa short action conversions, because that is what I am looking for. Both outfits make conversion kits for long action too, and PTG offers conversions for Remington in addition to Howa/Weatherby actions.