.223 Best All Around Twist Rate

[captonion]

This is the key... Captonian, you have far too many variables and far too small a sample size to draw "any" conclusions from your testing... statistical analysis is a complex process when variables are limited... in the testing you are doing there are far too many to control and thus no legitimate conclusion can be drawn. In addition, testing for heat in two different barrels, in an attempt to draw the conclusion you are determined to prove, is pointless.

Shooting the same load out of two of my rifles (same make barrel/ length). Only difference being rate of twist, one is 1/10 the other 1/8..Shot through the same Chrony at same distance there is about a 90fps difference..

Exact same load/bullet, both Douglas air gauge match barrels. Built on similar actions.. Everything equal!

I read this conclusion from many different sources. I to had reservations, so I tried it myself.. Came up with the same end result.. So this is not only my findings, I just wanted to see myself to if it was true.. It is!

The heat thing is a just for me experiment, just to see..

 

[hoytcanon]

Exact same load/bullet, both Douglas air gauge match barrels. Built on similar actions.. Everything equal!

I read this conclusion from many different sources. I to had reservations, so I tried it myself.. Came up with the same end result.. So this is not only my findings, I just wanted to see myself to if it was true.. It is!

The heat thing is a just for me experiment, just to see..

No two barrels are alike... including bore diameter... vagaries in the steel alone react differently to the bore process causing fluctuations in the constriction along the length of the barrel... chambers are different as is the leade, even if bored with the exact same reamer on consecutive chamberings... and then you have the cartridge itself and the loading, in addition firing pace and other factors... if you are to draw a legitimate statistical conclusion, you must isolate the factor/element you seek to investigate and have a sufficient sample size, so as to minimize infringement of unknown and/or suspected variables... kudos for messing around... I'm sure it was fun, but I wouldn't stand on a soap box quoting the results as though they are gospel... or even legitimate.

But as a result, you have two guns with nice barrels of different twist that you can work up specific loads for specific tasks... win.

 

[captonion]

But as a result, you have two guns with nice barrels of different twist that you can work up specific loads for specific tasks... win.

That I do, both on Vixen actions. Had them both built within a yr, one was to be for heavier bullets for deer. Decided to go a different rout, 6ppc is now the flavor of the week...

I'm sure it was fun but I wouldn't stand on a soap box quoting the results as though they are gospel... or even legitimate..

I would agree if it had been a marginal 20fps and passed it off as being caused by the barrel variations you list, but 90fps is alot IMO.
Like I said these aren't only my findings.. I read plenty on this subject with the same findings.. First article that turned me on to it was about target air guns. Went on to read publishing's in a number of magazines with the same findings with powder burners... Peaked my interest for sure...

 

[Boomer]

That I do, both on Vixen actions. Had them both built within a yr, one was to be for heavier bullets for deer. Decided to go a different rout, 6ppc is now the flavor of the week...



I would agree if it had been a marginal 20fps and passed it off as being caused by the barrel variations you list, but 90fps is alot IMO.
Like I said these aren't only my findings.. I read plenty on this subject with the same findings.. First article that turned me on to it was about target air guns. Went on to read publishing's in a number of magazines with the same findings with powder burners... Peaked my interest for sure...

Just out of curiosity, I have a few questions. How many rounds did you fire to determine there was an average difference of 90 fps between the fast and slow twist barrels? I only ask because a 90 fps difference in velocity would have raised a red flag for me, and personally, I would have wanted to make sure that such a difference in velocity was repeatable before I accepted it at face value.

What controls did you apply to your ammunition? Did you ensure the bullets were exactly the same weight, did you ensure your brass was uniform and of similar volume? Did you take any special precautions when weighing out your powder charges? Is neck sized only brass interchangeable between both rifles? Even what might be assumed is minimal variances can make large differences in chronograph readings.

What kind of chronograph do you use?

As one rifle, presumably the one with the faster twist, was built for use with heavier bullets, does it have a longer lead than the varmint rifle?

 

[Boomer]

You should be a politician!

First you say there would be NO difference (your findings). Then you list ways why the difference... Come on now, you are back peddling pretty hard here..

The question comes down to whether or not the BC of a bullet fired from a fast twist barrel suffers when compared to a similar bullet that is fired from a slower twist barrel. The only way this can be satisfactorily accomplished is to see which looses more down range velocity. You did not do this. To determine if the bullet's attitude in flight diminished it's BC, we need to know the muzzle velocity from both barrels, and we need to know the downrange velocity of both. If one bullet arrives down range with a significant difference between its muzzle velocity and its and its down range velocity, we can conclude that it's BC has been compromised.

As for concerns that different rates of twist have any significant effect on muzzle velocity, or barrel life, those theories have been proven to be unfounded by people much smarter than me.

 

[captonion]

As for concerns that different rates of twist have any significant effect on muzzle velocity, or barrel life, those theories have been proven to be unfounded by people much smarter than me.

It would seem so. Just got off the phone with a guy named Phil from Burger Bullets.. I gave him the very same question that you say isn't so, well apparently it is very much so... More bullet drag and friction being the cause.. He went on to say if I seated the same weight boat tail on the same charge that I should see less of a variation as there is less bullet surface area in contact with the barrel thus less drag, and friction..
Call if you like
714-441-7202

 

[captonion]

Just out of curiosity, I have a few questions. How many rounds did you fire to determine there was an average difference of 90 fps between the fast and slow twist barrels?

Over 80 rnds

What controls did you apply to your ammunition? Did you ensure the bullets were exactly the same weight, did you ensure your brass was uniform and of similar volume? Did you take any special precautions when weighing out your powder charges? Is neck sized only brass interchangeable between both rifles? Even what might be assumed is minimal variances can make large differences in chronograph readings.

Loads were very consistent in both rifles...

What kind of chronograph do you use?

A good one!

 

[KodiakHntr]

He went on to say if I seated the same weight boat tail on the same charge that I should see less of a variation as there is less bullet surface area in contact with the barrel thus less drag, and friction..

Been following this thread for a while now....Can you expand on that statement a bit? Less bullet surface area in contact with the barrel how?

 

[captonion]

Been following this thread for a while now....Can you expand on that statement a bit? Less bullet surface area in contact with the barrel how?

Take notice of the area the bullet will be in contact with the rifling.. I never thought about till pointed out.. Common sense.

 

[KodiakHntr]

Take notice of the area the bullet will be in contact with the rifling.. I never thought about till pointed out.. Common sense.

Ahhh, I see. Here I'd thought that you were comparing the SAME bullet in different rifles... Bearing surface is THE all important aspect when it comes to twist rates and velocity. I can see where your confusion comes in now on how you could be seeing 90fps difference.

Thanks

 

[captonion]

An article from Precision Shooter Magazine!

"Does Twist Rate Make a Difference in Velocity?
Yes. Our tests show that, with the 80-90gr bullets, a 1:10 or 1:12 barrel will give you as much as 80fps more velocity than a 1:8 barrel, shooting the exact same loads. Fast twist (1:8) barrels have more drag and friction, which can slow the bullet down. Ideally you want to use the slowest twist rate possible that will stabilize the bullet you choose to shoot. For a dedicated "point-blank" 100/200 yard Benchrest gun, you want a twist rate from 1:13 to 1:15. But if you want to shoot both light (60-80gr) and heavy (100gr+) bullets, stick with a 1:8."

 

[CV32]

An article from Precision Shooter Magazine!

"Does Twist Rate Make a Difference in Velocity?
Yes. Our tests show that, with the 80-90gr bullets, a 1:10 or 1:12 barrel will give you as much as 80fps more velocity than a 1:8 barrel, shooting the exact same loads. Fast twist (1:8) barrels have more drag and friction, which can slow the bullet down. Ideally you want to use the slowest twist rate possible that will stabilize the bullet you choose to shoot. For a dedicated "point-blank" 100/200 yard Benchrest gun, you want a twist rate from 1:13 to 1:15. But if you want to shoot both light (60-80gr) and heavy (100gr+) bullets, stick with a 1:8."

This appears in the Barrel FAQ at 6mmBR.com, btw.

This thread has certainly mutated. It went from bullet options for a given twist rate, to barrel life and "over stabilization", to velocity loss. I hope the OP isn't hopelessly confused (if he's even still here).

 

[captonion]

This appears in the Barrel FAQ at 6mmBR.com, btw.

Thank you. A bit more info there for me.. I am a magazine man, have a mountain of them, and buy them all the time..That is what I do to pass my time in Alberta work camps..

 

[DMS1]

Ahhh, I see. Here I'd thought that you were comparing the SAME bullet in different rifles... Bearing surface is THE all important aspect when it comes to twist rates and velocity. I can see where your confusion comes in now on how you could be seeing 90fps difference.

Thanks

He was comparing the same bullet and same load to get the 90 fps.

Based on the above pic I have some observations/assumptions that I'm not sure are correct:

1) the boat tail has less bearing surface, and is longer so it will require more twist than the flat base of equal weight?

2) the boat tail will be harder to push to the same velocity, since the gases have the whole surface area of the flat base bullet to exert pressure on?

I extrapolate to the 53gr Vmax - won't stabilize in a 1/12" twist that will easily handle 60 gr vmax (flat base).

 

[hoytcanon]

He was comparing the same bullet and same load to get the 90 fps.

Based on the above pic I have some observations/assumptions that I'm not sure are correct:

1) the boat tail has less bearing surface, and is longer so it will require more twist than the flat base of equal weight?

2) the boat tail will be harder to push to the same velocity, since the gases have the whole surface area of the flat base bullet to exert pressure on?

I extrapolate to the 53gr Vmax - won't stabilize in a 1/12" twist that will easily handle 60 gr vmax (flat base).

Except that all my 12 twists easily handle both bullets.

 

[CV32]

I extrapolate to the 53gr Vmax - won't stabilize in a 1/12" twist that will easily handle 60 gr vmax (flat base).

Using Berger's Twist Rate Stability calculator, I get values that produce marginal stability at best for the 53 gr Vmax in a 1 in 12 twist .223. The bullet is pretty long at apparently 0.829.

 

[hoytcanon]

Using Berger's Twist Rate Stability calculator, I get values that produce marginal stability at best for the 53 gr Vmax in a 1 in 12 twist .223. The bullet is pretty long at apparently 0.829.

Again... my older 12 twists (all Ruger's) shot the 53 VM's very accurately... as the did the 60 VM's... the 69 BTHP's were marginal and heavier/longer bullet's would not stabilize... my .223's are all 8 & 9 twists now... and the 68 and 75 BTHP's are my top two preferred bullets.

 

[KodiakHntr]

He was comparing the same bullet and same load to get the 90 fps.

Based on the above pic I have some observations/assumptions that I'm not sure are correct:

1) the boat tail has less bearing surface, and is longer so it will require more twist than the flat base of equal weight?

2) the boat tail will be harder to push to the same velocity, since the gases have the whole surface area of the flat base bullet to exert pressure on?

I extrapolate to the 53gr Vmax - won't stabilize in a 1/12" twist that will easily handle 60 gr vmax (flat base).

The biggest issue regarding twist is bearing surface. Overall length doesn't play into the equation when it comes to twist rate, it DOES factor in when you have to consider seating depth and magazine confines. When folks talk about lighter bullets shooting in slower twists, it doesn't have much to do with the actual weight, they just have a shorter bearing surface. (Although to be fair, velocity does come in to play with this. If you can push it fast enough, you might be able to spin it fast enough to stabilize.)

As to the boat tail/flat base, bear in mind that both bullets will seal the bore of the rifle, and will have the same pressures exerted.....

And no. Most 12 twists will handle the 60 gr vmax, but not many will spin a 53gr tsx (a bullet with a very long bearing surface) at 223 velocities (in my experience, at any rate.)

 

[DMS1]

I agree with most of the above, except I thought that I remembered the 60 gr vmax having more bearing surface than the 53 gr bullet. They stretched the ogive and added a boat tail, and its 10% lighter on the 53. For the 60, with the sharper corners on the flat base, I thought it left a lot more straight side. I don't have any left to compare, can anyone verify? Wouldn't be the first time I was wrong..

 

[KodiakHntr]

I agree with most of the above, except I thought that I remembered the 60 gr vmax having more bearing surface than the 53 gr bullet. They stretched the ogive and added a boat tail, and its 10% lighter on the 53. For the 60, with the sharper corners on the flat base, I thought it left a lot more straight side. I don't have any left to compare, can anyone verify? Wouldn't be the first time I was wrong..

You could be correct, I haven't flung many 60's and don't have any in front of me at the moment to compare. I mainly shoot the 50's and 75's and didn't see any benefit to the 60's.