If you built a rifle or just rebarreled a rifle what is ROT preference and why?

Wayne

It has to do with what weight bullet you will be able to shoot our of your rifle. Usually the more twist is required to stabize a heavier bullet after it leaves the barrel down range.

1~9 twist for me. It will work with virtually any bullet from 120grs to 175grs.

Wayne,

As Tonk says, it depends on what bullet weight you wish to shoot.

Most 7x57's have a 1~9" or 1~9.25 and some have 1~9.5"

My 1st 7x57 was a custom on a VZ-24... It had a 1~12" twist. I soon found out that any weight over 140 gr. was a waste of time. It wouldn't even shoot the 145 Speers... Personally, I am an advocate of heavier for caliber bullets. My preferred weight in the 7x57 is 154-160 gr. For that I prefer 1~8" or 1~8.5"...

There is a chart in Speer Manual #8 that lists optimum twist by bullet length. If you could round up a copy, that might make your decision easier... Hope this helps...

GH

In the half-dozen or so 7x57s I have owned, I have not been as fortunate as you. Most would shoot great with one or two bullet weights (150 - 175gr) and other weights so-so. One exception is a Ruger tang safety M77 with a 1-8.75 ROT that shoots respectable groups from 115gr to 175gr bullet range.

My intent is to get a rifle to shoot MOA or less with the 140 gr TTSX. The M77 and two other rifles will not accomplish that. The ROT in those rifles are 1-8.75, 1-9 and 1-9.5.

Do not have the #8 Speer Manual. It would be appreciated if you would look up the twist for a Barnes TTSX bullet - 1.362" bullet length.

Thanks - Wayne

Early Ruger 77 had 1 in 9 1/2" twist... Newer 77 Mk II have 1 in 8" twist. Note the attached chart where somewhere in the middle, Ruger used 8 3/4" twist.

Wonder which shoots best? with which bullet weight

7 x 57mm - 1 in 8" . . . . . . . . . . .Ruger (present)
7 x 57mm - 1 in 8 1/2" . . . . . . . .Winchester 70 (post 64)
7 x 57mm - 1 in 8.7" . . . . . . . . . .FN
7 x 57mm - 1 in 8 3/4" . . . . . . . .Winchester 54, 70 (pre �64); Ruger 77
7 x 57mm - 1 in 9" . . . . . . . . . . .Mannlicher-Schoenauer; Thompson/Center Rifle
7 x 57mm - 1 in 9 1/4" . . . . . . . .Remington 700
7 x 57mm - 1 in 9 1/2" . . . . . . . .Ruger 1, 77 (old); Savage 110
7 x 57mm - 1 in 10" . . . . . . . . . .Winchester 70


g

Well, I hate it when memory fails... The table I was thinking of is in Speer Manual #6 and it goes by weight. Can you tell me the approximate velocity that it will be going?

I just arbitrarily guessed 2600 f.p.s. According to the chart, a 160 gr. @ 2600 would call for a 1~9.5 twist. (I'm thinking the 160 gr would likely be near the same length...) Whereas my unprofessional opinion would lean toward a faster twist. I'm thinking like 1~8", especially since you've already tried it in slower twists... Now that I think of it, these charts would likely NOT apply to mono-metal bullets anyway... Sorry for the bum steer...

GH

GH, a member PM'd me with this twist calculator. Have you tried it, if so do you believe it is valid?

http://kwk.us/twist.html

I have never seen that calculator... But after looking at it, that's as good a guide as any... And I believe that one cannot predict it EXACTLY . For some unknown reason, there are always exceptions to the rule...

And as we should know, each rifle is a law unto itself!

GH

Wayne, as you know I used a 1-9 twist on my 7x57 and it shoots the 120gn GS Custom at 3235fps, the 160gn Woodleigh at 2700fps, and a 160gn cast at 2415fps all wirth very good accuracy. With the same scope setting on my 2-7 Leupold with LR retical the 120gn has a 250yd zero and the 160gn a 150yd zero. LR second bar gives the cast a 150yd zero. For me this twist works well and accuracy is certainly there for each intended purpose.

Von Gruff.

Yep, I know, you are hitting on all cylinders with that rifle.

The end game for me is to get the 140 gr TTSX to give accuracy with velocity. This would be a good set up to hunt everything in North America except for big bear.

Since those TXS bullets are longer than most, I would think that a faster twist barrel would be what you need to keep the bullet spinning on track and produce tight groups.

I have only shot a couple of 7 x 57 Mauser rifles, however it seems to me a 1 in 8 twist would be better for all those bullets above 140 grn upward.

Completed another range test of the 140 gr Barnes TTSX yesterday and I am a happy camper. Previously, I had given up on the bullet and went back to CnC's and partitions. A couple weeks ago I resumed testing and was again disappointed with results using H414, IMR4350, H4350.

My goal was to achieve 2,800 fps with MOA accuracy. What became clear was the closer I got to 2,800 fps the worse the accuracy became. Between 2,500 and 2,600 fps I was getting 2 inch five shot groups at 100 yds. Groups deteriorated with increased powder.

The Campfire's Seafire has recommended a fast powder load of 40 grs IMR 3031 and I get 2,700 to 2,725 fps and 1.5" 5 shot goups with the 140 gr NP. With same powder load and the 140 gr TTSX I get about 2,750 fps with 1.6" 5 shot groups.

This improvement with a faster burning powder got me to thinking about trying IMR 4320. Depending on the rifle, 44-45 grs produces 2,800 to 2,830 fps with five shot groups of .7 to 1" five shot groups.

Happy Camper! They can put a ban on lead bullets now.

ASSUME:
150gr eTip at 1.425" in length
MV of 2600 fps
Cool Arizona day



THEN:
1:9

Berger recommends a 1:9 for their 180 HVLD

kwk.us recommends 8.9 (round up to 1:9)

When doing a custom build I generally go w/ the fastest "standard" twist rate for the bore size I'm working with because I like heavy for caliber bullets, personally.

I'd strongly consider trying RL19 & RS-Hunter in the 7x57. I've had great results with those powders in that cartridge, although if you're going faster RL15 & RS-Big Game would be first stops for sure.

Good luck; I don't suppose there is anything you're likely to run across that'd stand up to a 140 TTSX at 2750 fps...

Or 2800 to 2830 fps...

Or a 160 TSX @ 2650 fps......

HaYen, thanks for the chart and info. The recommendations come out to about where I am at now with twists. As noted previously, three rifles - 1-8.75, 1-9 and 1-9.5.

When I first tried to get the 140gr TTSX to perform to my goal I considered re-barreling a rifle with a 1-10 or 1-10.5 twist. I partially based that on a friends Win M70 with a 1-10 ROT. It shoots the 140 TTSX - lights out. I know rifles are different, but I was willing to follow it's example.

Now it turns out that by going to a faster burning powder I can obtain the results that I hoped for. You just never what will surprise you.

That would be going against the latest trend that I am trying to become part of - lightweight monolithic bullets with speed.

I am a trendy kind of a guy.

Roundoak I forgot to tell you about IMR-4320 powder as it was something I found out years ago myself. I had a 6mm that would simply not shoot good over 27 or 2800 fps.

Then I found the 4320 and it was like a crystal ball on my bench. The hotter the load, the tighter the group. The rifle ended up shooting a .385-MOA that day. I too was a happy camper.

Geez!, Tonk if you would have told about IMR4320 in the beginning of this thread I could have saved some powder and expensive bullets, but you are forgiven...

I knew I shouldn't have clicked on a 7x57 thread, now I need to go test 4320.