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Joined: Apr 2005
Posts: 30,936 Likes: 1
Campfire 'Bwana
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Campfire 'Bwana
Joined: Apr 2005
Posts: 30,936 Likes: 1 |
OK that's what I couldn't exactly get my head around ,so if it starts at 1-10 and finishes at 1_9 it's it's going to continue at 1_9 throughout the rest of it's flight. Not quite, but it's a little more subtle. When it finished at 1-9 it was mechanically coupled to the barrel and its rifling. Downrange is different. As the bullet travels through the air its forward speed and rpm both decrease. Each 9 inches the bullet travels downrange takes longer than the previous 9 inches. The forward speed of the bullet decays faster than its rpm, so even though the spin is slowing the bullet gets more spin into each 9 inches of travel downrange. The faster you spin a bullet the tighter it spins increasing BC for really long range shooting. This is according to Brian Leitz and his team has won the 2 mile shoot multiple times.
Last edited by jwp475; 12/10/22.
I got banned on another web site for a debate that happened on this site. That's a first
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Joined: Jun 2004
Posts: 44,856 Likes: 3
Campfire 'Bwana
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Campfire 'Bwana
Joined: Jun 2004
Posts: 44,856 Likes: 3 |
[quote=1beaver_shooter]So I am guessing that the bullet will to continue to increase rpm's as it continues down range . Does this make it more stable at longer ranges 5,6,8 hundred yards or more ? Or is this project made up for the benchrest crowd to argue about? Come on mathman - DO YOUR RESEARCH! 🤣 I was quoting him. What are you talking about?
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Joined: Jul 2003
Posts: 1,458
Campfire Regular
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Campfire Regular
Joined: Jul 2003
Posts: 1,458 |
Supposed to mitigate bullet poofs. I'll expand on Tyrone's statement a bit since Service Rifle competition is one of the places you'll see gain twist barrels. We use fast twist barrels (up to 6.5 twist) to stabilize long skinny bullets (90gr) to improve wind performance. The fast twist coupled with pushing the 223 case HARD sometimes results in jackets coming apart downrange. A gain twist barrel supposedly starts off spinning the bullet more gently (9 twist) and accelerates the twist down the barrel until it's at 7 or 6.5")...I'm not sure if it works or not. I posed the question, if the rifling is essentially plowing a new furrow as the bullet goes down the barrel...how is that better for the jacket? I will say however that the folks that I know shooting a gain twist are getting crazy velocities. But is that a function of the gain twist or their lack of regard for pressures...again, I don't know.
Last edited by ChrisF; 12/10/22.
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Joined: Jan 2001
Posts: 8,226 Likes: 1
Campfire Outfitter
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Campfire Outfitter
Joined: Jan 2001
Posts: 8,226 Likes: 1 |
"if the rifling is essentially plowing a new furrow as the bullet goes down the barrel...how is that better for the jacket?"
That's something I've wondered about.
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