Twist for 270 Weatherby?

[MagnumManiac]

Excellent thread and I am so glad that someone brought this up about the 270 Wby Mag. With all the new, sexy calibers you don't see much about the 270 Wby anymore. I have had this exact same problem. I bought a Winchester Model 70 Pre-64 action chambered in 270 Wby Mag back in 1995. It was a tack driver with 130 bullets (Nosler Ballistic Tips and Swift Scirocco's). I got in a bind for reloading components one time and I loaded up some 150 grain bullets. When I tell you the gun wouldn't shoot them, it wouldn't shoot them. I couldn't keep the 150 grain projectiles in a group within 10" of each other. I do not know the twist of the barrel; all I know is it shoots 130 grain projectiles great and will not shoot 150 grain projectiles. My question to the group is this: does anyone know if it is possible for me to re-barrel this Winchester Model 70 Pre-64 action? I would love to re-barrel this gun with a 26" barrel 1 in 8" or 1 in 7.5" twist. Thanks guys

Yes, it is perfectly feasible to re-barrel your pre-64 rifle.
My rifle in question is a modern Model 70 EW that I built into a switch barrel, originally it was. 264WM, it also has 270Bee and 300WM.

Cheers.

 

[Lenny Foffa]

I'm late to this party do I apologize! I love my Weatherby MarkV in 270 Weatherby mag ! Purchased new in1979 or 1980!! 26 inch barrel ! Bueatifull deep. Bluing , no muzzle break! Just as it came from the factory ! I killed. Two mule fee and an antelope in Wyoming the first year ! My load 67.3 Grns IMR 4350 ! 3300 FPS Two years ago I shot out to 1100 yards with the. 150 Grn ABLRs! They worked so well! I have never tried the 170 grn Bergers ! I thought the standard factory 10 twist was too slow ! I love the caliber , and although I did kill one small spike bull elk in1980 something , I never considered the Rifle/ Caliber Elk Rifle! ! For me it's an excellent long range Deer / Antelope / sheep rifle ! As I hope to hunt elk one more time I will use its big brother ! Same Mark V Deluxe. In 300 Weatherby Mag ! If and when the 270 Weatherby needs a new barrel, I will most likely send it back to Weatherby! I think it's a great rifle in a great caliber and it will do just what it was designed to do, and do it very well !! So iit all comes back to what you need the rifle to do. If it need to be able to take big game as well as deer , then you may want a faster twist than 10 ! I'm guessing 9 or even 8 !

 

[assasinator]

My 24" 1:8 270 WSM shoots the 175 TGK great at 2850 FPS over RL-26 with what seem mild pressures (.100" jump). During load work, the bullet didn't display any of the bad behavior previously mentioned in this thread, and ended up shooting a lot better than the 165 ABLR, which I had actually built the rifle around, so to speak.
Have only used it last fall on a MT mule deer at 400 yards. First shot, (right quartering towards me) penetrated >36" and lodged in the left ham (recovered, with 62% weight retention). Buck stumbled a few feet and stopped. Second shot, (broadside) fully penetrated just behind the shoulder, and the buck dropped. Exit shown below.
I have read Browning uses a 1:7.5 twist on their 6.8 WSMs and this is the hunting bullet they load in their 6.8W ammo, but 8" seems fine to me, though I am just a little faster than the 6.8W.

Best of luck and sorry for the troubles life has recently thrown at you.

RexView attachment 577387

love your results man.

i am personally committed to the 150ABLR, 165 ABLR, 170AB, and the 170 EOL. if i had better pressure results with the 175TGK i would be inclined to use the rest of the bullets i have. i mean 175 grains does have it's benefits in spite of the bad BC.

i do have to note that with my 7 twist i truly believe my 270's accuracy is, in part, related to the extra twist.

i'll have more results as i shoot the 3.50" COAL 270 weatherby with my long freebore. my length to rifling touchup is 3.89"

BTW when i loaded the 175TGK i had 3.69" touchup for that bullet. with ..200" freebore and a starting load i should NOT have encountered excessive pressure. i added .200" more throat length after that shot.

 

[assasinator]

I have used 175 tgk in a 1-8 270 wsm, a 1-7.5 6.8W and another 1-8 6.8W. Super bullet. Very accurate and tough. Significantly beefier jacket than something like eldx. Will shoot through both shoulders and gristle plate of large boar hog and exit. Not common with cup and cores and I shoot different ones all the time. As for shape, Sierra shaped it so would work in a short action which was a goal of the 6.8W. With longer ogive it would not fit in SA OAL without ogive of bullet going inside case mouth. This is also why they did not do a 7mm and why the 7prc is a long action and not a short action. The longest 7mm high bc bullets need a LA for same reason

Lou

well, i never considered that the 175 TGK is a tougher bullet. wow that is good info...

you know i am going to push the crap out of my 270 BEE rechamber 7 twist 27".

so i did talk to a sierra engineer about the 175tgk. with the drag, i cant see it really developing speed, and its BC is 'only' 560.

so a 170 ABLR will leave it in the dust after 150 yards....BUT if its a tough bullet that can take blowing through bone(shoulders) that matters to me.

i killed a 550lbs red stag at 235 meters with my 350 remington magnum. he was quartered to me and i aimed AT his giant shoulder. my 200GR barnes blew his shoulder apart, exploded his heart and lung. dead in 5 seconds.

THAT is a tough bullet.

so, the moral to the story is, a tough bullet matters. wish i heard the 175TGK has a purpose. its certainly NOT ballistic performance. its killing.

in the end, is that NOT what we are here for?

thanks for that info.

 

[Lou270]

I should say the 175 tgk is tough for a cup and core. The bullet is long and has a thick jacket. It also has a big hp behind the tip so opens well/fast at least blows big holes in coyotes. The core can slip like any cup and core I suppose though not recovered one which is why I think they are tough as big pigs are bullet stops. 165 ablr exit as well though I have not a real big boar with one. 170 bergers and 165 matrix do not exit though kill great and work like they should. Just keep in mind if need blood trails in my opinion. On deer the 170 bergers have exited though I never count on it since that is not what bullet dssigned to do

As for BC, keep in mind the sierra BC is listed at 1900 fps. It is likely correct. If you look at other bullets like the 7mm Sierra 165 tgk they show .510 up to 2600 and .610 at 2600 and above. Hornady published BC is at mach 2.25 which is 2500 fps. If Sierra published BC at 2500 fps like they do for some other bullets and Hornady does it would be higher though not "more accurate". I expect this is why Browning says the 175 tgk load has a BC of .617. It is probably at higher velocity BC to match Hornady marketing. Sierra BC are known to be accurate but it is frustrating the way they report them. It is not consistent at all across their offering

Lou

 

[TRexF16]

I should say the 175 tgk is tough for a cup and core. The bullet is long and has a thick jacket. It also has a big hp behind the tip so opens well/fast at least blows big holes in coyotes. The core can slip like any cup and core I suppose though not recovered one which is why I think they are tough as big pigs are bullet stops. 165 ablr exit as well though I have not a real big boar with one. 170 bergers and 165 matrix do not exit though kill great and work like they should. Just keep in mind if need blood trails in my opinion. On deer the 170 bergers have exited though I never count on it since that is not what bullet dssigned to do

As for BC, keep in mind the sierra BC is listed at 1900 fps. It is likely correct. If you look at other bullets like the 7mm Sierra 165 tgk they show .510 up to 2600 and .610 at 2600 and above. Hornady published BC is at mach 2.25 which is 2500 fps. If Sierra published BC at 2500 fps like they do for some other bullets and Hornady does it would be higher though not "more accurate". I expect this is why Browning says the 175 tgk load has a BC of .617. It is probably at higher velocity BC to match Hornady marketing. Sierra BC are known to be accurate but it is frustrating the way they report them. It is not consistent at all across their offering

Lou

Thanks Lou, you saved me some trouble of rebutting the earlier comments regarding the 175 TGK having a "bad" BC. It's just because it's listed for 1900 FPS. Here are pics of the 175 TGK, 170 BT, and 165 ABLR. Doesn't take a rocket scientist (though one WOULD add credulity) to see there's no way the 170 BT and the 175 TGK have the same BC (Nosler lists the 170 BT the same as Sierra lists the 175 TGK). I use .600 as my WAG and it describes my trajectory pretty well.