220 Swift, twist rate, barrel length

[buda]

Folks, I'm having a 220 Swift built. My idea is to have a 1-12 twist in a 24 inch barrel, shooting 50 to 60gr bullets. My question is that twist OK for the grain weight, and is the barrel length OK or would a 26 inch barrel be more accurate.

OR should I go for a 1-9 twist to handle 50 to 65 gr in a 24 inch barrel.

This will be my first Swift and will be used for target shooting relaxation and varmint reductions.

 

[Bart B]

With the speed 50 and 60 grain bullets will leave a 220 Swift, I think best accuracy will be with a 1:14 twist as 70 and 80 grain ones would also do well with that twist.

Note the little 222 Rem was the accuracy ticket in 1950's benchrest wins shooting 50 and 52 grain bullets in 1:14 twist barrels. They spun about 154,000 rpm. The Swift will spin them about 206,000 rpm from a 1:14 twist.

 

[Mikecr]

Bart, you're seriously confused about stability.
If stability was about RPMs, then this would be declared as such for bullets (it is not).
Stability is tied to displacement(relative) per turn, and 14" displacement per turn is too much for 70-80gr bullets -regardless of RPMs/velocity. That is, unless he's hunting from the summit of Mt. Everest.

He is right about 12tw or tighter, but not much tighter or he'll blow up light bullets at 220swift velocities.

 

[hemiford]

Hi, I hope not to hijack this thread.

I'm also interested in ordering a barrel for 220 Swift. In my case,
I would only shoot bullets in the 60-68 grain range, and the barrel
will be long at 30-inch. I was guessing 1:9 twist ? maybe 1:10 ?

Thanks !

 

[buda]

I've answered my question. My twist rate is going to remain at 1-12 with a 24 inch barrel. I will be shooting up to 63gr, but primarily 55gr.

 

[buda]

Hi, I hope not to hijack this thread.

I'm also interested in ordering a barrel for 220 Swift. In my case,
I would only shoot bullets in the 60-68 grain range, and the barrel
will be long at 30-inch. I was guessing 1:9 twist ? maybe 1:10 ?

Thanks !

According to Shilen chart the 1-9 is best if your going up to 68gr.
Regards

 

[Bart B]

Mike,

Here's a list of 22 caliber barrel twists in inches and the rifling angle at bore diameter each presents to the bullets. The angle at groove diameter will be about 2.6% more:

1:8, 4.91 deg. (same as 30 caliber 1:11 twist)
1:9, 4.39 deg.
1:10, 3.92 deg.
1:11, 3.58 deg.
1:12, 3.34 deg.
1:13, 3.05 deg.
1:14, 2.81 deg.

With the 14 inch twist barrel's rifling angle to the bullet path the least of all, how could it have too much relative displacement for 70 to 80 grain bullets?

Never heard of the term "relative displacement." Please elaborate. Is it the same as "jacket displacement" for bullets? That's happened with thin jackets on some 7mm bullets from magnums with 1:9 twists that conventional rifling weakened and they separated at the groove in them.

 

[J E Custom]

With the speed 50 and 60 grain bullets will leave a 220 Swift, I think best accuracy will be with a 1:14 twist as 70 and 80 grain ones would also do well with that twist.

Note the little 222 Rem was the accuracy ticket in 1950's benchrest wins shooting 50 and 52 grain bullets in 1:14 twist barrels. They spun about 154,000 rpm. The Swift will spin them about 206,000 rpm from a 1:14 twist.

+1

You may be able to use a 1;12 twist but I would not go any faster for the 220 Swift.

The fast twist 1 in 8 and 1 in 9 are best suited for the 223's velocities.

I have a 223 WSSM that has a 1 in 15 twist and it shoots all .224 bullets well.

At 4200 + ft/sec velocities the faster twist barrels required solid bullets because the jackets were being separated from the core upon firing and accuracy went out the window.

To date the little hotrod has reached 4600 ft/sec and no problems have cropped up with the jackets
or accuracy.

The 220 Swift is capable of 4200 ft/sec + with 50 to 55 grain bullets so a 1 in 12 to a 1 in 14 would be my choice with the bullets you mentioned. with lighter bullets I would recommend a 1 in 14 or even a 1 in 15 twist.

Just my opinion

J E CUSTOM

 

[Bart B]

The 220 Swift is capable of 4200 ft/sec + with 50 to 55 grain bullets so a 1 in 12 to a 1 in 14 would be my choice with the bullets you mentioned. with lighter bullets I would recommend a 1 in 14 or even a 1 in 15 twist.

I knew a guy years ago who rechambered and reparted his classic Win 70 in 22 Hornet to 220 Swift. It's .223" groove diameter 1:16 twist 24" barrel shot 40 and 50 grain bullets very fast and very accurate.

 

[Mikecr]

I have a 223 WSSM that has a 1 in 15 twist and it shoots all .224 bullets well.

This is absolute rubbish. In fact, a lie.

Bart, the displacement I'm talking about is inches of air density, per turn, to counter the overturning moment(drag). It's relative because air density is relative to conditions, and the displacement per turn decreases as the bullet slows down range.
Bullet stability requirements(twist requirement) are in displacement per turn (like 12:1), and this is relative to a displacement standard(Std Armory, Std.Metro, Std.ICAO) and drag within it.

Muzzle velocity and RPM notions for stability fail tests right off the bat, as they are tied to TIME instead of displacement. Notice no bullet makers declare stability requirements using velocity or RPMs. They use twist at a specified sea level std. atmosphere. This is displacement -per turn -to overcome it.

It's been suggested here that great velocities from a 220 swift will overcome realities of stability requirements. This is not true at all. Displacement holds regardless of velocity/time through it.
For example; 69gr Sierra SMK, a pretty common bullet that needs a 10:1 twist under any SL conditions. In 14tw, even 10,000fps MV(514,000rpm) would not stabilize this bullet. Even if it didn't blow up(which it would), It would still tumble immediately.
An 80gr SMK in 14tw would not stabilize at ANY viable velocity, RPM, or atmospheric condition.
Same with a 75gr Berger VLD. These need 8" of displacement per turn, not 14".
Up in the 90gr bullets, you need 6.5-7:1.

A 15:1 22cal barrel WILL NOT shoot "all .224 bullets well"......

-14tw is good for 50-52gr
-12tw is good for 55-60gr
-10tw gets by for 60-70gr bullets at higher altitudes
-LR target bullets >65gr will need 8tw, all the way to 6.5tw

-All regardless of cartridge

 

[fasttrx88]

Tagging in this is getting good

 

[TOM H]

With the speed 50 and 60 grain bullets will leave a 220 Swift, I think best accuracy will be with a 1:14 twist as 70 and 80 grain ones would also do well with that twist.

Note the little 222 Rem was the accuracy ticket in 1950's benchrest wins shooting 50 and 52 grain bullets in 1:14 twist barrels. They spun about 154,000 rpm. The Swift will spin them about 206,000 rpm from a 1:14 twist.

Got a question. I shoot few 22 cal varmint rifles with 1/14 twist barrels and these are not factory barrels. Your claiming 70/80gr bullets would do well with that twist so what type groups and velocity you getting from your 220 Swift?

I'm not really interesting in RPM vs hearing actual data from your rifle.

 

[Bart B]

I've never said I had a 220 swift.

Only passed on what others have told me about theirs. Max loads and 1/2 to 3/4 inch groups at a hundred yards as I remember. Sierra Bullets claims good accuracy shooting 69 and 80 grain bullets from a Savage 1:14 twist 220 Swift barrel, both leaving at 3200 fps.

 

[J E Custom]

This is absolute rubbish. In fact, a lie.

Bart, the displacement I'm talking about is inches of air density, per turn, to counter the overturning moment(drag). It's relative because air density is relative to conditions, and the displacement per turn decreases as the bullet slows down range.
Bullet stability requirements(twist requirement) are in displacement per turn (like 12:1), and this is relative to a displacement standard(Std Armory, Std.Metro, Std.ICAO) and drag within it.

Muzzle velocity and RPM notions for stability fail tests right off the bat, as they are tied to TIME instead of displacement. Notice no bullet makers declare stability requirements using velocity or RPMs. They use twist at a specified sea level std. atmosphere. This is displacement -per turn -to overcome it.

It's been suggested here that great velocities from a 220 swift will overcome realities of stability requirements. This is not true at all. Displacement holds regardless of velocity/time through it.
For example; 69gr Sierra SMK, a pretty common bullet that needs a 10:1 twist under any SL conditions. In 14tw, even 10,000fps MV(514,000rpm) would not stabilize this bullet. Even if it didn't blow up(which it would), It would still tumble immediately.
An 80gr SMK in 14tw would not stabilize at ANY viable velocity, RPM, or atmospheric condition.
Same with a 75gr Berger VLD. These need 8" of displacement per turn, not 14".
Up in the 90gr bullets, you need 6.5-7:1.

A 15:1 22cal barrel WILL NOT shoot "all .224 bullets well"......

-14tw is good for 50-52gr
-12tw is good for 55-60gr
-10tw gets by for 60-70gr bullets at higher altitudes
-LR target bullets >65gr will need 8tw, all the way to 6.5tw

-All regardless of cartridge

I am humored at you calling me a liar, in fact it is another example of cowardly calling someone a name on line without having to say it to his face. I will be happy to send you a plane ticket to Texas so you can call me that to my face. (Be warned though the outcome will not be as pleasant as this response).

Just because someone doesn't agree with you or you don't agree with them there is no reason to resort to name calling. The only thing I can say about all that you posted is " I know where there is a barnyard full of the green stuff you are spouting".

It is however interesting that you know everything about other peoples rifles and the rest of us know nothing about anything. In fact I have no knowledge of how anyone's else's rifles shoot so you "MUST" be right.

To bad you had to ruin a good post, (Something this site is not used to)and I will have no more to say about it or to you, except the offer is still open for you to fly to Texas and not hide behind a computer.

Sorry Len, and guys but sometimes we just have to speak up.

J E CUSTOM