Thread: . 284 Winchester

Originally Posted by gundoc

I suspect that the .280 might well be a tad better than the .284 with modern powders.

Recently I plugged in some numbers to see what difference QuickLOAD calculated in muzzle velocities between the .280AI and the .284Win, as I'm also thinking of making a change, from the one to the other.

The inputs kept constant were: 162gr Hornady Amax, AR2209, 24" barrel, 6mm of shank engagement with the neck, the powder weight set for a simulated 60kPSI peak in both cases.

The .280AI required 59.9gr of powder for a 2920 ft/sec MV.
The .284Win took 55.0gr for 2870 ft/sec.

Close on a 5 grain difference for 50 ft/sec then. With the simulation tweaked to shorten the barrel to 16", then the predicted velocities were 2600 ft/sec and 2580 ft/sec respectively; the difference between the two cases was predicted to have dropped to only 20 ft/sec, while overall the loss of 8 inches had knocked the MVs back by around 300 ft/sec.

If the powder is changed to AR2213sc - a powder that might be considered as having a more suitable burn rate for the case capacities and bullet weight being simulated - then with the 24" barrel, and still 60kPSI peak, the predicted velocities are both slightly more, but not by much:

The .280AI required 62.9gr for 2960 ft/sec.
The .284Win took 57.6gr for 2900 ft/sec.

The difference between them for both charge weight and predicted muzzle velocity with the slower AR2213sc powder remains much the same as with AR2209. A shortened 16" barrel then gave the predicted velocities of 2630 ft/sec and 2600 ft/sec, again the Bush Pig length of barrel cuts what little velocity advantage there was with the larger .280AI case over the .284Win in half.


Having run a number of barrels in 280AI over the years I thought the larger case would be streets ahead, but if QuickLOAD's predictions bear out, this may not be observed. At this stage I haven't cross-checked against our .284Win data.

As far as the suitability of receiver and magazine lengths, the 6mm of shank in the necks for the old Amax used in this simulation gave CoLs of 89.3mm (3.52") for the .280AI, and 79.9mm (3.15") for the .284Win. While that may well be a representative CoL for a good match to many .280AI chambers, reamers for the .284Win can often be found throated long for 180gr Bergers (intended for competition use), and the resulting CoL for bullets positioned anywhere near the rifling may be quite a bit longer than this 3.15" figure, meaning single loading for short actions.
A common second problem arises if the intention was to use lighter bullets, in that there will be no option other than huge jumps on these for the necks to have any sort of reasonable grip on the shanks. We've also had neck clearance problems - again there appears to be considerable variation between reamers, and in the neck thickness for the different sources for brass. I think it can be safely stated, and without fear of contradiction, that the .284Win is a cartridges where it pays to check the reamer for suitability for the intended application before spinning the lathe.

Some very interesting comparisons puffin. If we are comparing the improved version of the .280, perhaps we should compare it to the .284 Shehane? I think your figures show that the .284 is pretty efficient. I spent a lot of time reading before I decided on mine.

Either way, both are great all-rounders for all NZ game.