Follow-up to Thread on 22" Win Mag
This is a .300 magnum story but H&H magnum. 20 years ago, I came across a 1949 Winchester model 70 Super Grade at a gun show. The price was low due to the fact that it had been cut off at both ends, ie., a recoil pad and a barrel chop to 21". The front sight had been replaced, the work was well done and it even came with the Super Grade sling swivels, so I own it. A few years later at another gun show, another pre-64 Winchester with the original 26" barrel at a good price. So I own that, too.
I do a lot of shooting over an Oehler 35P chronograph and I keep records. The following, FWIW, are comparisons, 21" vs 26" barrels, of similar handloads (same powder, same charge, same bullet) of velocities from similar rifles of same make and model:
150 gr. 3215 vs 3400 fps
165 gr. 3102 vs 3288 fps
180 gr. 2920 vs 3029 fps
220 gr. 2695 vs 2794 fps
It was unexpected that there is so little difference from 5" of barrel length from a cartridge that takes that quantity of slower burning powder. The loss is only 100 fps from the 180 and 220 gr. loads. With the lighter bullets, the loss approaches 200 fps but is still considerably faster than can be realized from a 24" .30/06. But I guess 20 to 40 fps loss per inch is what we have been told and this data bears that out. And this short barrel may be faster than the next one. Maybe one day I'll start a thread on my short barreled .30/06's.
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Very good info Ambrose. If I remember correctly, in the Barsness article I mentioned in the other thread, he started with a 30" tube on the .270. Seems he collected data as he progressively cut and recrowned the barrel, 2" at a time, all the way to 20". I think he determined 26" was the sweet spot, for that particular rifle, with performance very near the .270 Weatherby.
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that was exactly my point. yes you can get more velocity but at what overall cost.
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