Twist Vs Length

Tackleberrywho

Considering goin 1/8 twist on my .223 Varmint Rifle.

Will be running 75grain Superperformance.

Question is, How short can I go.

Currently 26" 1/12
And grouping well @ 100 200 & 300
I hope to group better or same with a shorter barrel.

She will be a Truflite.

I'm wondering is 22" just to short to stabilize 75 Grain rounds.

My Motivation is to have a more agile rifle, that still has 600 yard capabilities.
She will have a mod on board so 22"+4" Mod would make the Rifle manageable
Rather than the 30" that she currently is with Mod on.

(and would it be Hearasy to go 20" on a Custom Barrel)

BELOWaverageIQ

I have a 20" Shelin barrel on my .223,, its one of the most accurate rifles I have ever seen.

tomcat220t

Tackleberrywho wrote: »

Considering goin 1/8 twist on my .223 Varmint Rifle.

Will be running 75grain Superperformance.

Question is, How short can I go.

Currently 26" 1/12
And grouping well @ 100 200 & 300
I hope to group better or same with a shorter barrel.

She will be a Truflite.

I'm wondering is 22" just to short to stabilize 75 Grain rounds.

My Motivation is to have a more agile rifle, that still has 600 yard capabilities.
She will have a mod on board so 22"+4" Mod would make the Rifle manageable
Rather than the 30" that she currently is with Mod on.

(and would it be Hearasy to go 20" on a Custom Barrel)

A mate of mine shoots a C/Z 1/9 twist shortened to 22" and it finds the 75gr hornady stabilizes fine .So with the little extra punch of the superformance and tighter 1/8 twist trueflight setup, your suggesting should work fine.Or you could just buy a .204;)

clivej

Tack there lots of info out there out how much MV you loose with each 1" of barrel cut off.
The length does not not effect twist of the bullet I THINK. It should still be doing the same rotation on leaving the barrel.

tomcat220t

clivej wrote: »

Tack there lots of info out there out how much MV you loose with each 1" of barrel cut off.
The length does not not effect twist of the bullet I THINK. It should still be doing the same rotation on leaving the barrel.

The lenght of the barrel will effect the M/V which in turn would have an effect on the rotation of the round ,imo.

Vegeta

clivej wrote: »

Tack there lots of info out there out how much MV you loose with each 1" of barrel cut off.
The length does not not effect twist of the bullet I THINK. It should still be doing the same rotation on leaving the barrel.

tomcat220t wrote: »

The lenght of the barrel will effect the M/V which in turn would have an effect on the rotation of the round ,imo.

I think you're both correct

If a bullet is rotating once every 8 inches (1 in 8) length of the barrel wont change that figure.

Muzzle velocity does effect the revolutions per second and revolution per minute of the bullet though.
Which makes sense, if a bullets muzzle velocity is twice as fast then it must rotate twice as fast to get that 1 rotation in every 8 inches

dev110

I was just wondering say if you had a 24" barrel with 1:8 twist the round will rotate 3 times before it leaves the barrel but if you go to a 22" barrel it only turns 2.75 times and 20" barrel only turns 2.5 times.

What would this affect?

clivej

dev110 wrote: »

I was just wondering say if you had a 24" barrel with 1:8 twist the round will rotate 3 times before it leaves the barrel but if you go to a 22" barrel it only turns 2.75 times and 20" barrel only turns 2.5 times.

What would this affect?

Yes but it will turn once in 8", 1in8, and will still be rotating 1 in 8 as it goes down range. MV will only effect how many times it will rotate in a sec/min, it will still be rotating 1 in 8, allowing for fall off as it looses momentum.

Just the way I think it will be I could be wrong here.

It wasn't me!

You need to predict a velocity envelope and choose your twist rate based on that. Obviously you'll also need to consider the type of bullet, both weight and design, which you intend to shoot. Some lighter bullets might have a longer bearing surface in contact with the rifling, and therefore require tighter twists to stabilise. However, you could push that too fast and stability gets compromised. Obviously, as you get shorter, you get slower, so maybe 1:9" might be better from 20-22". Hard to say without doing the maths, but you need to figure out your velocity first and foremost. Second, if you intend using the Hornady stuff, make sure you have enough of it to burn out the barrel or you're going to run into supply issues and you've no guarantee that your barrel will shoot anything else. (It's probable, but some barrels are fussy) I'd talk to Hornady first and foremost, along with your dealer. First step is to make sure they have a rough figure you should expect in terms of velocity and that you'll never have ammo supply issues, then figure out the twist rate you need based on what you can expect and order a barrel in that length which you've decided on.

Tackleberrywho

tomcat220t wrote: »

A mate of mine shoots a C/Z 1/9 twist shortened to 22" and it finds the 75gr hornady stabilizes fine . The berger and hornady stuff could make a fine long range round for hunting

So with the little extra punch of the superformance and tighter 1/8 twist trueflight setup, your suggesting should work fine. Thats my thinking

Not interested in the calibre as I'd like the option of competing in .223 comps Or you could just buy a .204;)

I want to stay .223.(many reasons here, including no licensing changes)
I am very impressed with all Hornady Ammo, So I hope to be truly impressed with 75grain Superperformance which has the same drop chart as 55grain stuff I am currently using.

Tikka is 1/8 in .223 and chews all ammo well.
Tikka also run much shorter barrels.
Remington have started using faster twists in shorter barrels.
There must be a reason for this.

20" would be ideal sa it would make the rifle far more versatile at night with a lamp on, yet still capable of the odd 600 yard bunny during the day (I hope)

mayfly36

I have the tikka t3 lite in 1:8, its the 20 inch barrel, 510mm, and thats factory length, not shortened by me, so i cant see nothing stopping you.

here have a look at their data sheet.

http://www.tikka.fi/pdf/datatable.pdf

Tikkat3

Tackleberrywho wrote: »

Considering goin 1/8 twist on my .223 Varmint Rifle.

Will be running 75grain Superperformance.

Question is, How short can I go.

Currently 26" 1/12
And grouping well @ 100 200 & 300
I hope to group better or same with a shorter barrel.

She will be a Truflite.

I'm wondering is 22" just to short to stabilize 75 Grain rounds.

My Motivation is to have a more agile rifle, that still has 600 yard capabilities.
She will have a mod on board so 22"+4" Mod would make the Rifle manageable
Rather than the 30" that she currently is with Mod on.

(and would it be Hearasy to go 20" on a Custom Barrel)

Although not specifically for the .223, some good reading to be found HERE

Tackleberrywho

Tikkat3 wrote: »

Although not specifically for the .223, some good reading to be found HERE

Reading between the lines 24" seems to be a good 600 yard barrel

Shorter, but stiffer so better barrel harmonics

They also mention **depending on rifling**
Which leads me back to thinking twist is proportional to length

Are Shorter Barrels More Accurate? As a general rule, the answer is yes. A shorter barrel will be stiffer, pound for pound, since you can run a thicker contour (diameter) with the same weight. As you increase diameter, barrel rigidity rises to the 4th power of the increase. But if you lengthen a barrel, stiffness declines in proportion to the cube of the length. So a barrel that is just a few inches longer and a bit thinner can be half as rigid as a 20" max contour barrel (More details). The added stiffness of fat 20-22" BR barrels raises barrel harmonic frequency to the point that barrel vibration becomes a non-issue (provided the bedded action is rigid as well). Common sense tells us that it is easier to make a shorter piece of steel perfectly straight, and with less bore length to drill, there is less chance of a flaw in a shorter barrel. Benchrest competition proves that short barrels, in the 20-22" range, give maximum short-range accuracy in 6mm, assuming you use a scope

virminhunter

sorry for bumping in on your thread tack:o but I think its a related question maybe you can answer it for me, you see lads using 30inch barrels in ftr with .308's so the bullet doesn't drop below the sound barrier before it reaches 1000yards, when does a .223 drop below the speed of sound and would this be a factor in relation to barrel length when shooting at 600yards with a .223?

Tikkat3

Tackleberrywho wrote: »

Reading between the lines 24" seems to be a good 600 yard barrel

Shorter, but stiffer so better barrel harmonics

They also mention **depending on rifling**
Which leads me back to thinking twist is proportional to length

Found it a good read and I am glad it helped with your question.

I have the 24" Tikka Tac .223 but never figured out why the last few inches of the Barrel is flared but guess it could be to do with harmonics.

Tackleberrywho

virminhunter wrote: »

sorry for bumping in on your thread tack:o but I think its a related question maybe you can answer it for me, you see lads using 30inch barrels in ftr with .308's so the bullet doesn't drop below the sound barrier before it reaches 1000yards, when does a .223 drop below the speed of sound and would this be a factor in relation to barrel length when shooting at 600yards with a .223?

i don't shoot FTR .308, My .308 is Hunting Only.

In regards the .223 falling below speed of sound?

What I intend using

Test Barrel (24") Velocity (fps) / Energy (ft-lbs)
Muzzle 100 200 300 400 500
2930/1429 2694/1209 2470/1016 2257/848 2055/703 1863/578

poulo6.5

well tack. its looking like most people would agree that a short barrel is the best option.
i am of the opinion that 20" is long enough but i am after a rifle that is usable and accurate. and when adding a mod you are going to be up another 4".

it does of course matter if you want to use it for target shooting in which case you are going to want a long barrel. but then you are back at square one with a long barrel.

my tikka tac has a 20" barrel and i have fired it with great results out to 500y ye have all seen the pic so i wont bore ye with it again but it shows that a good short barrel is very capable of performing at long range.

if you were not brave enough to go 20" then 22" or maybe even 24" but you have to choose what you want to do with this rifle its in your hands at the end of the day.


i put the numbers threw the ballistic calculator on the hornady website for the 75gr superformance out to 1000y and it is still above super sonic at that range


Ballistics Table in Yards
hornady 75gr superformance 75 gr., .395 B.C. www.hornady.com
Range (yards) Muzzle 100 200 300 400 500 600 700 800 900 1000
Velocity (fps) 2930 2695 2471 2259 2057 1865 1687 1522 1375 1247 (1144)
Energy (ft.-lb.) 1430 1209 1017 850 704 580 474 386 315 259 218
Trajectory (100 yd. zero) -1.5 0.0 -3.3 -12.2 -28.0 -52.1 -86.2 -132.6 -194.1 -274.2 -376.9
Come Up in MOA -1.5 0.0 1.6 3.9 6.7 10.0 13.7 18.1 23.2 29.1 36.0


in reality how far will you be shooting it and will an extra few fps be worth more weight and less usability

20" is the way to go.

Tackleberrywho

I'd like to be able to shoot my permissions where I have a couple of fields with bunnies that 600 yards is available.

I'm thinking 24" as a min standard
(yes I am afraid to go 22" in case the groups are sh*te @300, as she currently groups well at that range)

stick shooter

For field and some target shooting i would go 24" 1/8 twist , You will achieve the velocity you require with this combination .With the help of hps ammo you can get 80gr match ammo for long range target to stabilise in the 1/8 . And In time to come you feel you dont need that length barrel very easy shorten it , but you cant add it on .

poulo6.5

http://www.youtube.com/watch?v=15qj032UJ1I&feature=feedrec_grec_index

shorter does not mean less range