twist rates and bullet weight

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twist rates and bullet weight

Post by newgunner » 22 Mar 2018, 7:51 pm

hi guys,
just want to verify the lower the twist as in 1:8 the heavier the projectile/bullet it can fire safely
what should i be using in 1:8 twist 65 grain or higher?
Will a 1:8 twist still fire 55grain ok or will it destabilise the bullet due to the twist?
i am only using factory at present till i figure out what i need to reload

thanks
Last edited by newgunner on 22 Mar 2018, 8:17 pm, edited 3 times in total.
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Re: twist rates and bullet weight

Post by sungazer » 22 Mar 2018, 7:57 pm

1:8 will still shoot a 50grn no problem and it will be able to shoot upto a 80grn perhaps a bit more depending on bullet design. The 1-9 twist pretty much only maybe gets to 75 depending on bullet design there may be an 80 it will shoot but it wont be a long pointy hi bc bullet in general.
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Re: twist rates and bullet weight

Post by Apollo » 22 Mar 2018, 9:03 pm

newgunner wrote:hi guys,
just want to verify the lower the twist as in 1:8 the heavier the projectile/bullet it can fire safely
what should i be using in 1:8 twist 65 grain or higher?
Will a 1:8 twist still fire 55grain ok or will it destabilise the bullet due to the twist?
i am only using factory at present till i figure out what i need to reload
thanks


What calibre might help..??

There are a lot of factors that are involved with twist rates and bullet weight plus others like bullet shape, length.

In the old days when bullets were not made to the same quality as they are now, shooting a very light weight bullet in a very fast twist rate might cause the bullet jacket to fail (fly apart) due to the pressure created by the internal lead plug.

These days the problem is with bullets that are too long and too heavy for a slow twist rate that the bullet will NOT stabalise and will tumble instead of spinning correctly.
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Re: twist rates and bullet weight

Post by Spiney » 22 Mar 2018, 9:28 pm

If the calibre is a .223, as per your previous post a day or so ago, then you should be right with the 55g bullets. I've shot numerous different bullet weights in my .223 ruger american ranch rifle to date. Everything from 55g upto and including 75g and they all performed as expected ie. they didn't tumble. The 55g aussie outback ammo however was far and away the most accurate with a group of just under 1/2" at 100 metres.
So far CZ 455 22lr, Ruger american ranch 223
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Re: twist rates and bullet weight

Post by southeast varmiter » 23 Mar 2018, 5:46 am

It’s not bullet weight that determines stability and twist.
It’s bullet length. Hence you’ll get away with some heavier projectiles.
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Re: twist rates and bullet weight

Post by eddahenry » 23 Mar 2018, 7:52 am

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Re: twist rates and bullet weight

Post by bladeracer » 23 Mar 2018, 8:50 am

newgunner wrote:hi guys,
just want to verify the lower the twist as in 1:8 the heavier the projectile/bullet it can fire safely
what should i be using in 1:8 twist 65 grain or higher?
Will a 1:8 twist still fire 55grain ok or will it destabilise the bullet due to the twist?
i am only using factory at present till i figure out what i need to reload

thanks


My Ruger American is 8"-twist and shoots 35gn to 80gn just fine.
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Re: twist rates and bullet weight

Post by bladeracer » 23 Mar 2018, 8:53 am

Apollo wrote:In the old days when bullets were not made to the same quality as they are now, shooting a very light weight bullet in a very fast twist rate might cause the bullet jacket to fail (fly apart) due to the pressure created by the internal lead plug.


Also with bullets swaged from .22LR cases, but this can be mitigated by reducing velocities.
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Re: twist rates and bullet weight

Post by SCJ429 » 07 Apr 2018, 7:17 pm

With enough rpm, induced by high volosity and fast twist rate, the bullet jacket runout can cause the bullet to come apart in flight. This is unlikely to occur in a 223 shooting 55 grain projectiles. You may find that you cannot shoot light projectiles with higher jacket runout as well as a 1:14 barrel in a 222 due to the rpm. You will however be able to stabilise longer lead free projectiles like the Barnes varmint grenades that a 1:14 would not. The 1:8 223 barrel that you have is very versatile but excels with 60 to 80 grain projectiles.
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