Twist rate for .257 115 to 130 monos; 257 AI

[salmonchaser]

Sending off my ruger 257 roberts for a new barrel, I never should have bought a bore scope. Anyway going to have PAC NOR make me a 257 AI. Looking at 6 months out. Want to be able to shoot the heavier monos perhaps. Thinking on a 1/8.5 instead of the standard 1/10. What say you all?

 

[JD338]

The 257 AI has a ton of cool factor! I don't think it's a bad idea to go with the 8.5t. it will give you more options. A 6 month wait isn't too terrible. It will still give you 3 months for load development.

JD338

 

[AFG270]

I had PacNor rebarreled my m70 to a 25-06 several years ago, they did an excellent job. I went with a 1in9 twist, wish I had gone with an 8 or 7.5. Hammer bullets makes some great monos, they are accurate and deadly on game.

 

[RL338]

Want to be able to shoot the heavier monos perhaps.

I’d be looking at 7t or 7.5t if they supply them.

 

[Slimfinn]

I'd say 7.5" thats what the standard twist for the 25 creed so I would think alot of the new bullets would be based around that. That said hammer has one or 2 of theirs that need a 7"

 

[salmonchaser]

I just looked at some of the Hammers, I might just go faster than I first thought.

 

[JMRhino]

I also had PacNor make a .257 WSM barrel for me years ago and it does great with 115-120 cup and core and 80-100gn monos. It is only a 1/10 and has a tight throat so I haven't tried anything heavier. It produces great accuracy with traditional loads...

 

[salmonchaser]

My #1 is very accurate with 100 gr BT. Ok with 110gr Accubonds but they have been hard to find. The rifle really doesn’t care for anything 115 or higher. Best I can tell it is 1/10. She liked the 92 gr. Hammer as well. This particular rifle really only shoots the 100gr BT well, 3/4 moa consistently. Every thing else has been rejected out right or won’t break the 1 1/4 to 1 1/2 barrier. Even my 375 HH has two loads that go under 1moa.
I’ll probably increase the barrel length from 20 inches to 24 as well.

 

[SJB358]

I’d go 7.5 minimum myself and knowing me, I’d do a 7. Chances are it will still shoot 100 BTs great and it’ll open doors to about anything coming out you may wanna try. I’ve not found a problem with too much twist myself and probably overdo it but honestly I can’t see where it’s ever hurt me.

Increased RPMs do nothing but assist a bullet opening as well, from a light bullet moving fast or moderately heavier bullet moving a touch slower.

 

[cloverleaf]

Anybody know if Joel is alive? He could tell you everything you ever needed to know about the 257AI. I believe his was a model 70 featherweight. somebody should be able to give you the right twist rate. Whats a .25 Creedmore running? I would think that would work....CL

 

[SJB358]

Anybody know if Joel is alive? He could tell you everything you ever needed to know about the 257AI. I believe his was a model 70 featherweight. somebody should be able to give you the right twist rate. Whats a .25 Creedmore running? I would think that would work....CL

He is still alive. He made his 257AI into a 6.5x47 Lapua last I knew.

 

[EOD Diver]

Gents,
I’ve been looking at this too for the wife’s 257 Roberts. Hornady makes a 112 CX bullet for the 25 Creed that has my complete attention! The BC is really up there and I love the penetration you get with monos. Although they don’t list the length, I did a little math based on Accubonds vs E-tips of the same weight and caliber and got something roughly in the neighborhood. From this, it looks like 7.5 is where you want to be. Wouldn’t you know it but that’s the twist rate on the 25 Creed.
V/R,
Joe

 

[salmonchaser]

Gents,
I’ve been looking at this too for the wife’s 257 Roberts. Hornady makes a 112 CX bullet for the 25 Creed that has my complete attention! The BC is really up there and I love the penetration you get with monos. Although they don’t list the length, I did a little math based on Accubonds vs E-tips of the same weight and caliber and got something roughly in the neighborhood. From this, it looks like 7.5 is where you want to be. Wouldn’t you know it but that’s the twist rate on the 25 Creed.
V/R,
Joe

Immagine that. I think running those long bullets out of the old deer slayer just might work real well.

 

[SJB358]

Immagine that. I think running those long bullets out of the old deer slayer just might work real well.

I’d think so. Probably up the ante a bit being a mono.

 

[Blkram]

My research after getting my new-to-me LH Sako in 257 Roberts last year showed that the 257 was hampered by the 1:10 twist, where many were finding that it would not properly stabilize the heavier bullets (115-120 gr) properly for utmost accuracy, and that those that rebarreled to a 1:9 twist finally found what they were looking for. I may end up rebarreling it to the 1:9 as I would prefer to use the 115 gr BT in it (or maybe the 117 gr SGK), as it isn't quite there yet accuracy-wise with the 115 gr BT, and use my 110 gr ABs in my 250 AI (which has a 1:10 twist).

With the new 25 Creedmoor, and now the RPM, most are recommending 1:8 - 1:7 twists for the newer longer heavier bullets 120-138 gr range. It seems that they are recommending the 1:7.5 twist for bullets in the 125-130 gr range, and the 1:7 for those heavier than 130 gr. Actually ordered a 24" Benchmark 5R fluted barrel with 1:7.5 twist yesterday for my 25 CM project. As the 250 AI case is identical to the 25 CM, I will have one rifle for the lighter bullets, and one for the heavier bullets, in the same performance category. Should make ideal rifles for pronghorn, axis deer, fallow buck and blackbuck! (And African plains game such as springbok and gazelles.)

As a hunter, with most of the 130 gr bullets being match type, I will be preferring to stay in the 120-130 gr range for the new 25 CM.
If I need 130-140 gr or heavier, I will just grab the 6.5 CM or Swede, as both work very well on game (deer, caribou, and moose).

 

[JD338]

My research after getting my new-to-me LH Sako in 257 Roberts last year showed that the 257 was hampered by the 1:10 twist, where many were finding that it would not properly stabilize the heavier bullets (115-120 gr) properly for utmost accuracy, and that those that rebarreled to a 1:9 twist finally found what they were looking for. I may end up rebarreling it to the 1:9 as I would prefer to use the 115 gr BT in it, and use my 110 gr ABs in my 250 AI (which has a 1:10 twist).

With the new 25 Creedmoor, and now the RPM, most are recommending 1:8 - 1:7 twists for the newer longer heavier bullets 120-138 gr range. It seems that they are recommending the 1:7.5 twist for bullets in the 125-130 gr range, and the 1:7 for those heavier than 130 gr. Actually ordered a 24" Benchmark 5R fluted barrel with 1:7.5 twist yesterday for my 25 CM project.

As a hunter, with most of the 130 gr bullets being match type, I will be preferring to stay in the 120-130 gr range for the new 25 CM.
If I need 130-140 gr or heavier, I will just grab the 6.5 CM or Swede, as both work very well on game (deer, caribou, and moose).

Gil,
I agree with your thoughts. A 7.5t should really make your 25 CM sing.

JD338

 

[efw]

Back when I built my .257 Rob the fastest twist available was 1-in-8” and I got it.

I see no downside to a faster twist whatsoever. I can still shoot my 75s at coyotes & whistlepigs, and now I can shoot 128s at elk & mule deer if I’d like to.

Win/win

 

[Blkram]

I see that Sierra has announced a 131 gr Tipped Game King (TGK) that will be out this year. They have not yet listed its BC, but its SD will be 0.291. That will provide great penetration on larger big game such as our northern whitetails and mulies, and caribou with a quarter bore!
Checked with the gunsmith and he believes that the new Sierra will perform just fine with the 1:7.5 twist barrel I ordered, which arrived last week! (Was supposed to arrive in June; nice when something comes in sooner than expected!)
(They are pretty busy right now, and do not have space in their shop for my rifle at the moment, so it will go in in June after I get back from Africa, as originally planned, and he'll have some room as he wraps up some other projects for other clients between now and then.)

In another thread, which I haven't found again yet to respond, someone asked if my 24" Benchmark 5R barrel on my 6.5 CM was button or cut rifled, and if I knew what the 24" 25 CM would be.
Upon asking my gunsmith, he stated that Benchmark only brought out the cut rifled barrels a few years back, so the 6.5 CM would have been button rifled when done, and producing the great accuracy (at least to my standards) that inspired the query.
He wasn't sure if the 25 CM barrel is buttoned or rifled, and would have to check the barrel stamp (but believes that it may be rifled).
If rifled, will be an interesting comparison in performance between the two!

I am looking forward to experimenting with the 25 CM!
As stated previously, I have dies, Nosler brass, Hdy 128 gr ELD-X bullets to use with F210M primers and various powders to try (VN555, H4350, Re-16, StaBall 6.5, HD and Match, and Superformance) to experiment with, that should produce velocities in the 2800-2900 fps range. (And then repeat again once I have some of the new 131 gr TGKs!)
And I finally found some of the new Hdy 128 gr ELD-X ammunition for break in, and sighting in the VX-5HD 3-15x44 B&C scope, once the LH Browning X Bolt All Weather is rebarreled.

 

[salmonchaser]

Well my 257AI project is on hold though the rifle is still in the shipping box. My retirement fund has lost so much money in the last month that I can’t justify spending any at this point. Thankfully I pulled my Africa money out just before things went south. It had been sitting in the Africa fund for four years so I’m happy with that return.

 

[SJB358]

In another thread, which I haven't found again yet to respond, someone asked if my 24" Benchmark 5R barrel on my 6.5 CM was button or cut rifled, and if I knew what the 24" 25 CM would be.
Upon asking my gunsmith, he stated that Benchmark only brought out the cut rifled barrels a few years back, so the 6.5 CM would have been button rifled when done, and producing the great accuracy (at least to my standards) that inspired the query.
He wasn't sure if the 25 CM barrel is buttoned or rifled, and would have to check the barrel stamp (but believes that it may be rifled).
If rifled, will be an interesting comparison in performance between the two!

I’m praying for you that you got some rifling in the .257 barrel Gil. It’d be a stern talk with BM if they forgot