Barrel twist vs muzzle jump? Does slower twist make a difference?

[NC/Br Shooter]

How does barrel twist rate affect muzzle jump?
Iv Been reading in the archives and found a thread on 30br, where they where talking about when they went from using 15 twist barrels to 17 and how big of a difference it made in the bag.
At my last match, a friend there mention something along these same lines, where he was saying his 14 twist gun would track with ease compared to his 8 twist 6mm. Actually that conversation got me thinking and putting two and two together in the sense that Iv heard it mentioned that some guys like to choose barrel that just will give enough rpm. Maybe I heard that some F open shooters talking about it. Point being, These where things Iv heard in the past but when I heard it, it didn't resonate.
So in benchrest shooting ppc vs 6br, is this a reason why ppc dominants in short range? Fast light bullets , slower rpms. Less movement on ignition through bbl ? I understand that 6br can have a 13.5 bbl.
So, does slower twist rate make a difference?

 

[NZ_Fclass]

It feels like it should....but as I only shoot F class...and only shoot long bullets, I will have to put up with it.

 

[AlNyhus]

Yes, twist rate makes a difference in how a gun torques in recoil.

With twist rate being the only change, a good analogy is to think of twist rate like using a breaker bar on a bolt....with gun being the 'bolt'. A faster twist rate is like using a 'longer' breaker bar.

Good shootin' -Al

 

[SKWERLZ]

Yes, twist rate makes a difference in how a gun torques in recoil.

With twist rate being the only change, a good analogy is to think of twist rate like using a breaker bar on a bolt....with gun being the 'bolt'. A faster twist rate is like using a 'longer' breaker bar.

Good shootin' -Al

^^^^^

You feel it more as twist than jump.
Especially on bigger calibers with a iffy setup/bipod.

 

[Sykes]

Interesting stuff. Would the breaker bar effect be the reason why when my form isn't 100% my rifle will recoil and jump left? Never to the right.

 

[AlNyhus]

Interesting stuff. Would the breaker bar effect be the reason why when my form isn't 100% my rifle will recoil and jump left? Never to the right.

Think about how the rifling turns.

 

[K Hope]

How does barrel twist rate affect muzzle jump?
Iv Been reading in the archives and found a thread on 30br, where they where talking about when they went from using 15 twist barrels to 17 and how big of a difference it made in the bag.
At my last match, a friend there mention something along these same lines, where he was saying his 14 twist gun would track with ease compared to his 8 twist 6mm. Actually that conversation got me thinking and putting two and two together in the sense that Iv heard it mentioned that some guys like to choose barrel that just will give enough rpm. Maybe I heard that some F open shooters talking about it. Point being, These where things Iv heard in the past but when I heard it, it didn't resonate.
So in benchrest shooting ppc vs 6br, is this a reason why ppc dominants in short range? Fast light bullets , slower rpms. Less movement on ignition through bbl ? I understand that 6br can have a 13.5 bbl.
So, does slower twist rate make a difference?

There is Jump and then there is Jump; barrel jump and bullet jump and they are very much related.

Notionally with a hummer barrel and superman bullets highest accuracy is achieved; however in the real world with an imperfect bullet a faster barrel twist produces less accuracy.

Have a look at Bison Ballistics web site under Barrel twist and Bullet Stability – Lateral Throwoff.

Aerodynamic Jump is also related to barrel twist. See diagram further down on same page.

As to the PPC dominance check out the equipment list of the major competitions. As M. Ratigan says in his book…. Bullets! Bullets! Bullets!

 

[Ned Ludd]

Interesting stuff. Would the breaker bar effect be the reason why when my form isn't 100% my rifle will recoil and jump left? Never to the right.

Generally speaking, muzzle hop to the left is potentially a different animal than what might be observed by the increased torque with a faster twist barrel. I cannot state with 100% certainty that your form behind the rifle is the sole cause of the leftward hop, but it easily could be. Try angling your body to either side of "straight back" behind the rifle and see what happens to the direction of the "hop". What I have found is that if I move my feet in the same direction as the hop, thereby angling my body just slightly more in that same direction, it changes the angle of my shoulder pocket and will tame or completely eliminate the hop. If I angle my body enough in the same direction as the hop, I can usually make the muzzle hop in the other direction, i.e. go too far. Experimentation at the range should reveal the optimal position to minimize muzzle hop caused by the angle of the shoulder pocket, and it can be different for different shooters.

As has already been noted, increasing twist rate will increase torque with a given bullet weight and muzzle velocity. It may not be all that noticeable if the load only has very light recoil to begin with. But if it does, you may notice more of a feeling that the rifle is trying to turn or twist around the barrel longitudinal axis as opposed to the muzzle hopping noticeably.

 

[marchx]

The other part of the equasion is bullet stability. If you go to slow with a twist rate you may not be able to stabilize the heavier bullets. Therefore, I choose the slowest twist capable of stabilizing my bullet.

 

[RGRobinett]

"Perception becomes reality" . . . back when we obtained our initial batch of PacNor 1:18" twist, 5-groove barrels, and began kicking posterior (NBRSA Hunter Class events), most people, tasked with shooting an "old school" thirty caliber barrel (14/15" twist), and one of the "new" 18" twisted barrels, using the same ammo, would pronounce that the 14/15" barreled rifle recoiled more . . .
I always opt for a twist rate which will impart minimum Sg 1.4 with the LONGEST bullet I intend to use - and going to Sg 1.5 provides a "killer'good" safety-net of gyroscopic stability while, with quality bullets, maintaining BR competitive precision. RG