.270 Win. Ackley Improved Load Data

The .270 Ackley Improved (.270 AI) is a wildcat rifle cartridge based on the classic .270 Winchester, modified using P.O. Ackley’s “improved” case design. It retains the same .277-inch bullet diameter but features a steeper 40-degree shoulder and reduced body taper, which increases powder capacity and improves case efficiency. The result is higher attainable velocities without a proportional increase in chamber pressure.

In practical terms, the .270 AI typically delivers 50–150 feet per second more velocity than standard .270 Winchester when using similar bullet weights, most commonly in the 130–150 grain range. This translates into a slightly flatter trajectory, marginally improved downrange energy, and excellent performance for medium-to-large game such as deer, elk, and plains game.

One of the cartridge’s advantages is versatility: rifles chambered in .270 AI can safely fire standard .270 Winchester ammunition, which fire-forms the brass to the improved chamber. This makes brass sourcing straightforward for handloaders. Additionally, the improved case shape often results in longer case life due to reduced stretching.

However, the .270 AI is not factory-standardized and generally requires handloading and a custom-chambered rifle. Its performance gains are meaningful but modest, appealing primarily to experienced shooters seeking incremental improvements rather than a dramatic step up from the traditional .270 Winchester.