223- are there any disadvantages to a fast rate ?!

[billy_boy_2010]

Hi guys

As above- looking to buy my first 223 as a dedicated fox gun with occasional range use. It will sit nicely between my HMR and 308.

I have read into twist rates (I have never given it much thought before!) and understand that a fast twist rate allows the shooting of heavier bullets. Up to 70gr. As a result It also is potentially more suited to copper bullets, should they become a legal requirement.

However- are there any disadvantage to a fast twist rate ? Do they struggle to shoot the lighter 50gr bullets that the 1 in 12 guns shoot so easily? Do they spin ballistic/fragmenting bullets (so very useful with fox) too fast And cause them to break up in the air ?

Any advice would be great thanks.

[dromia]

Actually faster twist rates allows you to shoot longer bullets not necessarily heavier.

As usual sloppy internet "experts" have corrupted the meaning by using bullet weight as an unhelpful proxy for bullet length.

[billy_boy_2010]

Fair point- and I think I knew that to a certain extent.

But copper bullets are inevitably longer aren't they- for a given weight?

Any other thoughts on the above?

[snayperskaya]

Actually faster twist rates allows you to shoot longer bullets not necessarily heavier.

As usual sloppy internet "experts" have corrupted the meaning by using bullet weight as an unhelpful proxy for bullet length.

Spot on advice from Dromia right here.......as an example the original twist rate of the Russian Dragunov was 1:320mm but it was later changed to a faster 1:240mm twist, this was done in order to facilitate the use of tracer and armor-piercing incendiary ammunition, since these bullet types required a faster twist rate for adequate stabilization due to the extended length of those bullets even though they are very similar to the light ball projectile weight-wise.The knock on effect was a slight reduction in accuracy when using either the 7n1 sniper round or the standard 57-N-323S LPS round from the 1:240mm barrel.

[dromia]

Fair point- and I think I knew that to a certain extent.

But copper bullets are inevitably longer aren't they- for a given weight?

Not necessarily, that is why the weight proxy is unhelpful.

Sierra 2156's are longer than 2155's but both are 155 grain. The 2156 has a better BC being a different shape and longer but not heavier.

[1066]

If you were only shooting fox with fast light/short bullets (50-55gn) a 1/12" would serve you well, however a 1/9" or 1/8" will be more versatile. There are plenty of 1/9" .223's around now, they will happily shoot the 55gn bullets with very little detrimental effect but will also handle the longer 65-70gn bullets well. My old CZ 527 Varmint with a 1/9" shoots 62gn GGG military ammo quite comfortably out 600 yards. Although I reload for everything I shoot I will often not bother for the .223 for range work. I can't make it much more accurate or much cheaper.

[billy_boy_2010]

Actually faster twist rates allows you to shoot longer bullets not necessarily heavier.

As usual sloppy internet "experts" have corrupted the meaning by using bullet weight as an unhelpful proxy for bullet length.

Spot on advice from Dromia right here.......as an example the original twist rate of the Russian Dragunov was 1:320mm but it was later changed to a faster 1:240mm twist, this was done in order to facilitate the use of tracer and armor-piercing incendiary ammunition, since these bullet types required a faster twist rate for adequate stabilization due to the extended length of those bullets even though they are very similar to the light ball projectile weight-wise.The knock on effect was a slight reduction in accuracy when using either the 7n1 sniper round or the standard 57-N-323S LPS round from the 1:240mm barrel.

Interesting thanks. But why did accuracy suffer ?

Fair point- and I think I knew that to a certain extent.

But copper bullets are inevitably longer aren't they- for a given weight?

Not necessarily, that is why the weight proxy is unhelpful.

Sierra 2156's are longer than 2155's but both are 155 grain. The 2156 has a better BC being a different shape and longer but not heavier.

Ah ok- so if the shape and profile is identical a copper bullet will inevitably be longer- but one can change the shape to reduce length. Interesting.

[billy_boy_2010]

If you were only shooting fox with fast light/short bullets (50-55gn) a 1/12" would serve you well, however a 1/9" or 1/8" will be more versatile. There are plenty of 1/9" .223's around now, they will happily shoot the 55gn bullets with very little detrimental effect but will also handle the longer 65-70gn bullets well. My old CZ 527 Varmint with a 1/9" shoots 62gn GGG military ammo quite comfortably out 600 yards. Although I reload for everything I shoot I will often not bother for the .223 for range work. I can't make it much more accurate or much cheaper.

Ok thanks- seems like there are no real disadvantages to a faster twist rate and it gives me more options :)

[Mike95]

My Savage has a 1 in 9 twist and shoots 69/75 grain bullets very well. For some reason it does not like 62gn !
Will also shoot 50/55gn no problem..

Mike95

[snayperskaya]

Actually faster twist rates allows you to shoot longer bullets not necessarily heavier.

As usual sloppy internet "experts" have corrupted the meaning by using bullet weight as an unhelpful proxy for bullet length.

Spot on advice from Dromia right here.......as an example the original twist rate of the Russian Dragunov was 1:320mm but it was later changed to a faster 1:240mm twist, this was done in order to facilitate the use of tracer and armor-piercing incendiary ammunition, since these bullet types required a faster twist rate for adequate stabilization due to the extended length of those bullets even though they are very similar to the light ball projectile weight-wise.The knock on effect was a slight reduction in accuracy when using either the 7n1 sniper round or the standard 57-N-323S LPS round from the 1:240mm barrel.

Interesting thanks. But why did accuracy suffer ?

I would hazard a guess that as the faster 1:240mm twist rate stabilised the longer bullets better it destabilised the shorter bullets slightly.

The Soviet military accuracy standard required of 7n1 sniper ammunition (148 grain bullet) allowed for no more than 1.24 MOA extreme vertical spread with 1:240 mm twist rate barrel but no more than 1.04 MOA extreme vertical spread with 1:320 mm twist rate barrels......a difference of around 19% between the two twist rates.

Length-wise a Soviet/Russian T-46-M tracer bullet is a fair bit longer than the standard steel-core LPS bullet with an average weight difference of only a few grains, around 146 grains for the tracer compared to 148 grains for the LPS.The B-32 armour-piercing incendiary bullet isn't a lot heavier at 160 grains but is a hoofing great thing length-wise, probably around a third longer than the LPS bullet.