I've been peripherally watching the YouTube riflemen talk about the latest and greatest rifle cartridges.
The topic that seems to be bantered around is heavy bullets in common bore sizes. When we increase the weight of a given bullet, it gets longer in the bore. That requires a faster twist to stabilize the bullet. Of course, with a long skinny bullet we get better ballistic coefficient. That translates into greater energy downrange.
I ran into this problem when I was working up loads for the .243 Winchester. The standard 1:10 barrel would stabilize bullets up to 100 grains, but when I started playing with those lovely long, skinny 107s, I started having stabilization problems. No problem, just back down to the 100 grain bullets and place your shot.
Other folks have talked about the demise of the .270 Winchester. Like this clip from Ron Spomer. It seems that the Western hunters wanted a faster twist in the .270. And, it appears that Browning is offering a 1:7.5 twist. That's fine, that's all well and good. The .270 Winchester is far from dead. There is no telling how many thousands of them are in closets, safes and gun racks across the country. The .270 Winchester ain't going anywhere.
2 comments:
Sigh... How many times have we been down 'this' road over the years???
It’s a balance thing. Too fast a twist will over stabilize lighter bullets. Which means they never nose over when the trajectory gets steep. A faster twist will go straighter through game, but it will also cause the bullet to mushroom more. If it mushrooms back past the center of balance it becomes unstable in the game , go sideways, and not penetrate to the vitals you want hit for a clean kill.
If you ever run across the old A-Square loading manual there a nice essay on this.
Read something similar recently about some subsonic rifle with insanely fast rifling. Like 1 in 3. Thing shoots big heavy bullets real slow. Worthless for anything else. It’s all a balancing act.
If I ever get rich I will build a throated .45-70 with a 1 in 10 twist 26” barrel. A few grains of Unique will push a 500-600 grain bullet at about 1000fps. And be nearly silent without a suppressor. But 1:10 will be ok for supersonic bullets down to 300gr. Win win. My idea of balance.
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