What is the best twist for a 7x57 shooting mostly 140 to 160 grain bullets? This is for a hunting rifle. It will have a 22" #2 contour douglas barrel.

Mine is a 1:9. Works fine.

7x57 twist rates over the years:

1/8.7 FN
1/9 MS
1/9.5 Ruger
1/10 Winchester 70

As far as "best", a faster TR with handle heavier bullets, but you probably already knew that.

How does the faster or slower twist effect the ideal range for bullet weights? does the slower twist such as 1:10 tend to be more ideal with generally lighter bullets? Would this fit my need for maxing out at 160s? And if I did shoot 175's would it still stabalize them...even if less than ideal?

tha's about right, although the 160's are probably better off with a 9" or shorter twist. i think you'll find most use 9" for 140's as well and leave the really light stuff to the 10" barrels. the 140's are sort of the "break even" line betweeen 9&10" twist. the general rule of thumb says that a little extra spin won't do as much harm to accuracy as even just a tiny bit too slow of a twist. so you should bias your twist selection on the faster side of the lightest bullet weights you will most likely use.
that said, my 7x57 improved is 9 inch and i don't see anything detrimental with the 130's i shoot occasionally.

I think we may be defining things a bit differently. Just to clarify the discussion……The faster twist rate would have the lowest number. So of the several listed above the fastest twist rate is 1:8.7. One full revolution of the bullet in 8.7 inches of the barrel. The Slowest twist rate is 1:10. One full revolution of the bullet in 10 inches of bullet travel. Heavier bullets work better with faster twists. Such as the 1:8.7. Lighter bullets work best with slower twist rates such as the 1:10.

All that being said….Douglas offers both the 1:9 and the 1:10 twist rates for the .284. Between those two. Which one would be most ideal for my 140 to 160 grain range? Most of the bullets I plan to load are between 139 and 150 grains. Would the 1:10 twist rate suit me best?

quote:

Originally posted by Iron Buck:

Most of the bullets I plan to load are between 139 and 150 grains. Would the 1:10 twist rate suit me best?

Good question. My 7x57 has a CIP twist of 1:220mm (8.66").

With 140s, it shoots 2" at 100 yards.

With 160s, it shoots 1/2" at 100 yards.

Have not tried the 150s, as the 160s seem to kill everything they hit.

From an accuracy stad point I seriously doubt you would see any difference in the 1:9 vs 1:10 on the lighter bullets. However you might on the heavier. McGowan lists a 1:10 up to 140s and Shilen a 1:11 for up to 140s both say 1:9 for bullets heavier than 140. In my wifes 7x57 it is a 1:9 and it handles 120-160 just fine. To me it is better to error to the faster twist side.

The 9in twist is probably the best to use for general work as it covers the 140 - 160 gn bullets. My 7x57 wears a 25in by 9 twist and handles everything from the 120gn GSC HV up through 160gn Woodleigh to 168gn Bergers. IMHO the 9 in twist is best for hunting purposes.

Von Gruff.

Queston on twist rate affect on velocity. I have a Hart 30-338 26 inch with one in 12 twist. I out ran my 7 STWs with a ten grain heavier bullet. 140 Gr 284 @ 3517mph and the 150Gr 308 @ 3573. Does the slower twist rate in theory offer less resistance to the bullet traveling down the bore? Inquiring mind want to know!

Fast twist will affect velocity if all else remains the same, which it usually doesn't. In other words, it can be measurable, but not significant. 7x57 twist should be 1 in 9.5 or quicker IMO. I would probably be happy with the 1in 8.5. as I shoot the long TSX's in 140's, and 160 partitions.

How does the twist affect velocity? Is faster or slower twist more conducive to faster or slower velocities? I have never read anything regarding this before. Interesting.

From What I am reading here. Since I will be using a Douglas barrel....I think I am going with the 1:9 twist.

ironbuck,
basicly correct, but more or less such an inconsequential amount that it's not even considered until there a wide mismatch in twist and bullet weight/length, such as a twist for the lightest bullets and shooting the heaviest. a faster twist will slow things down a bit, but actually it's a mute point. you get what you get in velocity with the heavier bullets in a fast twist, as long as the twist is fast enough for the bullet, no problem, the twist will stabilize the bullet. with lighter bullets the notion of the twist slowing things down and thereby decreasing the bullets spin rate is of no to little concern.....a lighter bullet doesn't need all the spin and even if it's overspun a bit, it will have less detrimental affect on the bullets stabilization than if you had a slower twist and tried driving the bullets harder to speed thier rate of spin up. the latter can obviously lead to loose primer pockets and multi-pieced rifles, omongst other, more painfull situations.

quote:

How does the twist affect velocity? Is faster or slower twist more conducive to faster or slower velocities

I believe you are really worrying about problems that won't exist. Go with your 1:9 and you will be very happy.

quote:

Originally posted by new_guy:

My 7x57 has a CIP twist of 1:220mm (8.66").
With 140s, it shoots 2" at 100 yards.
With 160s, it shoots 1/2" at 100 yards.

Anyone else had a similar experience?

quote:

Originally posted by new_guy:

quote:

Originally posted by new_guy:

My 7x57 has a CIP twist of 1:220mm (8.66").
With 140s, it shoots 2" at 100 yards.
With 160s, it shoots 1/2" at 100 yards.

Anyone else had a similar experience?

I've had the same experience with my 7 MM RUM. At 100 yds it was a wide group but at 300 yds it straightened out it's yawl and really tightened up. Some times certain bullets need some time in flight to wake up and fly straight.

quote:

Originally posted by Iron Buck:
What is the best twist for a 7x57 shooting mostly 140 to 160 grain bullets? This is for a hunting rifle. It will have a 22" #2 contour douglas barrel.

Iron Buck,

Most 7x57's came with the old German standard twist rate, which became the CIP twist rate later on, being 1:220mm or 8.66" for every turn. Reason being that it was designed for 173 gr FMJ lead-core bullet at the time being fairly long for caliber (high SD bullet).

Over time factories and custom bullet makers came up with their own designs and more bullet weights - from 110 grains to 175 grains. Also, monolithic bullets made their appearance about a 100 years after the launch of the cartridge. USA factory loads only came out in 140 grain bullets for the 7x57, which is fine, but there is much more potential too be tapped from this caliber. Just try it with 175 gr Swift A-Frame bullets and you have a combination in your hands that will surprise most sceptics of this dinky caliber.

My rifle, with its standard CIP twist rate, shoot 140 grain Nosler bullets as well as the 160 grainers. I tried some 160 gr TSX bullets and they also group under half an inch. The twist is fast enough for monolithics and should not be an issue, even the 175 gr Barnes-X bullets stabilize, but they are very long and so rob too much powder space.

I would stay with the standard CIP specification.

Warrior

I have them in 1-10 and 1-9.5" twists, and they work well. I only shoot 140 grain Parttitions, or 100 grain Sierra HP's; 140's for Deer and the light weight bullets for Coyotes.

quote:

Originally posted by craigster:
7x57 twist rates over the years:

1/8.7 FN
1/9 MS
1/9.5 Ruger
1/10 Winchester 70

As far as "best", a faster TR with handle heavier bullets, but you probably already knew that.

As can be seen, the USA manufacturers (Ruger & Winchester) opted for a slower twist rate, in line with the 140 grain bullets that they or ammo makers load for. Ferderal in particular offers a 140 gr load with Nosler Partitions, and out of the box I achieved a fantastic grouping with my rifle.

Warrior