Twist Rate

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TenMetrePeter
Posts: 1043
Joined: Wed Jun 29, 2016 5:40 pm
Location: Luton Beds UK

Re: Twist Rate

Tue Jul 23, 2019 8:07 am

Blackbaronfish wrote:
Tue Jul 23, 2019 6:27 am
A HMR travels at 2150 + FPS with a 17 grain bullet.
A 223 will travel 3000 FPS with a 40 grain bullet.
Just in case you was board :lol:
Centre fire twist rates vary from 1in 8 to 1 in 12

BBF
270,000 rpm
Thats insane!

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tonyc
Posts: 376
Joined: Mon May 29, 2017 10:55 am

Re: Twist Rate

Tue Jul 23, 2019 4:08 pm

TenMetrePeter wrote:
Mon Jul 22, 2019 11:05 pm
You needed feet per minute. Everyone gets it wrong.

Length of pellet is only a factor in that a longer pellet is heavier therefore slower at 12ftlb

I don’t have the gyro formula for mass and angular velocity but I wouldn’t mind betting the faster spin has more stability.

Discuss.

(Can’t you sleep either? :lol: )
I think you may find the moment resulting from larger diameter and mass of the .22 may offset the higher spin rate of the .177. It's too many years since I did any moment of inertia calculations - and I don't recall anything to do with gyros - so I'll leave others to sort this out! :geek:

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