IIFID, one set of comparisons that I made -- which you may have seen on one of these boards about ten months ago -- compared my .220 Howell and the .22-6mm Remington. These two are almost the same size -- 56.6 grains of water (.22-6mm) versus 61.2 grains of water (.220 Howell). I ran several comparative simulations by computer, using of course the same criteria for both cartridges.
<br>
<br>The same .224 bullet -- the 75-grain Hornady A-Max
<br>One velocity -- 3,500 ft/sec
<br>To see, in the first comparison,
<br>(a) which powders and charges would propel the same bullet at the same muzzle velocity
<br>(b) the peak pressure resulting from each charge in each case
<br>
<br>In the .22-6mm,
<br>52.0 gr Ramshot Magnum -- 56,540 lb/sq in.
<br>48.4 gr IMR 7828 -- 56,896 lb/sq in.
<br>49.0 gr Vihtavuori N560 -- 54,994 lb/sq in.
<br>
<br>In the .220 Howell:
<br>54.6 gr Ramshot Magnum -- 50,465 lb/sq in.
<br>50.7 gr IMR 7828 -- 51,299 lb/sq in.
<br>51.3 gr Vihtavuori N560 -- 49,835 lb/sq in.
<br>
<br>For my second comparison, I used the same bullet and the same three powders to see
<br>(a) which charge of each powder would produce
<br>(b) which velocity
<br>at the typical SAAMI maximum peak pressure of 60,000 lb/sq in.
<br>
<br>In the .22-6mm,
<br>52.8 gr Ramshot Magnum -- 3,563 ft/sec
<br>47.9 gr IMR 7828 -- 3,459 ft/sec
<br>50.2 gr Vihtavuori N560 -- 3,596 ft/sec
<br>
<br>In the .220 Howell,
<br>56.6 gr Ramshot Magnum -- 3,766 ft/sec
<br>51.1 gr IMR 7828 -- 3,631 ft/sec
<br>53.8 gr Vihtavuori N560 -- 3,794 ft/sec
<br>
<br>For my third comparison, with the same bullet and the same powders, I checked to see
<br>(a) which charge of each powder would produce
<br>(b) which velocity
<br>at my preferred maximum peak pressure of 50,000 lb/sq in.
<br>
<br>In the .22-6mm,
<br>50.4 gr Ramshot Magnum -- 3,368 ft/sec
<br>46.6 gr IMR 7828 -- 3,358 ft/sec
<br>47.6 gr Vihtavuori N560 -- 3,394 ft/sec
<br>
<br>In the .220 Howell,
<br>53.9 gr Ramshot Magnum -- 3,549 ft/sec
<br>49.8 gr IMR 7828 -- 3,531 ft/sec
<br>50.9 gr Vihtavuori N560 -- 3,570 ft/sec
<br>
<br>Since both these cartridges are significantly larger than the .220 Swift and .220 Ackley Improved Swift, the performances of both the .22-6mm and the .220 Howell are correspondingly better than either version of the Swift can produce under the same criteria. The .220 Howell, for example, is about 25% to 30% more capacious than the original Swift.
