Twist Rate: How Does It Improve Performance In the Hunting Fields?

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Not joining the debate again...but thought this might be pertinent info if some finds this thread while actually looking for information.
I pulled this from the web.
LRAB.png

The 168s are "marginally" stabilized in my 1-9.5, and it shoots fine in my conditions. It put 4 shots into one double sized hole, and cracked a neck and had a shot 1" high.
The original bc was supposed to be .65 ish, I'm using a .600 to match trajectory with my start velocity of 2900fps. Even tho accuracy is good, I think Llamas right, poor conditions and it would probably wobble pretty good.
After these two boxes I'm dropping to the 150s, or yanking my tube and installing a 1-7 or 8.
 
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Llama Bob said:
Ignored since you didn't answer the question about where I can find an equivilent .277 bullet. Your ignorance continues.
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Why would you need one at hunting ranges?

What would it do for you?

Being 10 gr. heaver and starting at 200 fps faster, what difference does twist rate make at normal hunting ranges?

Would it be heavier than 150 gr., thereby overburdening the cartridge and negatively impacting field performance, like the 6.5 CM/143 gr.?




GR
 
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Llama Bob said:
If you're referring to the .277 150gr Accubond LR, you're wrong. Numerous people have dopler radared it now, and it wobbles badly in flight. That's why Nosler recommends a 1:9. It won't keyhole in a 1:10 until the temp drops, but even at room temp the BC will suffer.
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If you want to know if a bullet is wobbling just look at the shape of the bullet hole in a paper target. An accurate smooth flying bullet will make a round clean hole in the target. I usually shoot 200 meter targets and much of my shooting is at low temperatures and the first thing I do when I walk up to the target is to look at the shape of the hole and the cleanliness of the hole. I didn't need dopler radar to figure this one out.
 
Garandimal said:
Seems like the 125 gr. .264, in a hunting bullet, is the best use of the little cartridge in the field.

It appears, academically at least, to even outperform the 130 gr. .270 Win.

Why not use that?




GR
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For me it would usually be the same reason to use a 150 or heavier .277, or a 160+ .284
I like soft bullets, but they need more weight to exit than a harder lighter projectile.

The 140 class 6.5s exit easily on our 80-120lb Axis deer, and open gaping holes in the off side. They are more than I need for the 40-100lb sheep and goats tho, and if I didn't prefer to stock one bullet for all my cartridges in a cal, I'd use 123-130s in my 6.5CM since its mostly a geep gun.
My 6.5-284 drives 140s to 2950-3k depending on the powder I can get, that one benefits from the extra weight.

sage5907 said:
If you want to know if a bullet is wobbling just look at the shape of the bullet hole in a paper target. An accurate smooth flying bullet will make a round clean hole in the target. I usually shoot 200 meter targets and much of my shooting is at low temperatures and the first thing I do when I walk up to the target is to look at the shape of the hole and the cleanliness of the hole. I didn't need dopler radar to figure this one out.
Click to expand...

I've just ordered some 150ablrs for a friend's new .270. Another buddy shoots them, but this will be the first time I'm going to get to spend time with a .270 and these bullets.
I'll take it to Maunakea (10k ft, low 70-60s) to check stability, and try get an adjusted bc. If I get the chance I'll try duplicate the same distances at sea level, but since there's only one place I hunt where I can, it may not happen.

I'll see if I can discern a wobble, honestly I'm betting I see a bc reduction, but can't tell on target.
 
Garandimal said:
And, if driven at 200 fps faster, with greater weight for a similar SD than, say, the little 6.5's? Then, at normal hunting ranges, they should out-perform the smaller cartridge, at least until both are well down range with paper-punching only energies.
Click to expand...
What's the advantage of using 50% more powder and adding recoil to achieve the same terminal performance at range?
I like old stuff as much as the next guy, but I recognize the efficiency of modern case, bullet design when combined with a proper twist
 
sage5907 said:
If you want to know if a bullet is wobbling just look at the shape of the bullet hole in a paper target. An accurate smooth flying bullet will make a round clean hole in the target. I usually shoot 200 meter targets and much of my shooting is at low temperatures and the first thing I do when I walk up to the target is to look at the shape of the hole and the cleanliness of the hole. I didn't need dopler radar to figure this one out.
Click to expand...
It's entirely possible for the bullet to make a perfectly round hole to the eye and yet not be fully stable.
 
mavracer said:
What's the advantage of using 50% more powder and adding recoil to achieve the same terminal performance at range?
I like old stuff as much as the next guy, but I recognize the efficiency of modern case, bullet design when combined with a proper twist
Click to expand...

Well... that sounds like a Magnum you are describing.

The ranges referred to are those considered typical hunting - out to maybe 3-400 yards.

The -03 class of cartridges use ~ 25% more powder - to push a heaver bullet of similar SD ~ 200 fps faster. (no free lunch in Physics)




GR
 
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LoonWulf said:
For me it would usually be the same reason to use a 150 or heavier .277, or a 160+ .284
I like soft bullets, but they need more weight to exit than a harder lighter projectile.

The 140 class 6.5s exit easily on our 80-120lb Axis deer, and open gaping holes in the off side. They are more than I need for the 40-100lb sheep and goats tho, and if I didn't prefer to stock one bullet for all my cartridges in a cal, I'd use 123-130s in my 6.5CM since its mostly a geep gun.
My 6.5-284 drives 140s to 2950-3k depending on the powder I can get, that one benefits from the extra weight.



I've just ordered some 150ablrs for a friend's new .270. Another buddy shoots them, but this will be the first time I'm going to get to spend time with a .270 and these bullets.
I'll take it to Maunakea (10k ft, low 70-60s) to check stability, and try get an adjusted bc. If I get the chance I'll try duplicate the same distances at sea level, but since there's only one place I hunt where I can, it may not happen.

I'll see if I can discern a wobble, honestly I'm betting I see a bc reduction, but can't tell on target.
Click to expand...

Thanks for the interest and work. Look forward to your results.

And agree that the .308 based cartridges are good performers w/ the lighter bullets, while the -03 based cartridges are more efficient w/ the heavier bullets.

(and therefor high twist rates don't seem to be that relevant)




GR
 
mavracer said:
Ok fine what's the advantage of using 25% and more recoil?
Click to expand...

Well... as stated - The ranges referred to are those considered typical hunting - out to maybe 3-400 yards.

The -03 class of cartridges use ~ 25% more powder - to push a heaver bullet of similar SD ~ 200 fps faster. (no free lunch in Physics)

From there, it depends on what you think is required to do the work on particular game, in terms of terminal velocity, energy lb-ft, and quality of kill.

Considering the gambit of snaring and starvation (0.0 fps/ 0.0 lb-ft/ Slow kill), to a point blank 16"/50 Naval Gun (2500 fps/ 262,269,785.4 lb-ft before detonation/ Quick kill), and your own personal recoil envelope, applicable cartridges fall out.




GR
 
Barrett is putting 9 twist barrels on their .270 Win Fieldcraft rifles in 2019, which would be nice if you want to shoot the longer 150gr bullets. I never did get the accuracy I was looking for in my .270s with 150gr bullets longer than the NPT and SGKs, I suspect the 10 twist was my limiting factor as the rifles shot much better with pretty much every shorter bullet I tried. If a rifle in .270 I wanted was available in both 9 and 10 twist, I'd go with 9 no question, more bullet options, no downside.

The 25% increase in powder going from a short action cartridge to a long action referenced here is somewhat accurate for .308/.30-06, but is too low for a 6.5CM/.270 Win comparison.

Actual loads I use or have used in the past:

.308 (20") - 178gr ELDx, 43.8gr Varget, 2,590 fps
.30-06 (22") - 180gr Accubond, 56gr H4350, 2,800 fps.

.308 (22") - 165gr SGK, 45.5gr Varget, 2,750 fps.
.30-06 (22") - 165gr SGK, 59gr H4350, 2,920 fps

Powder increase from .308 to .30-06 for these loads respectively:

27.8% (34 fewer shots per lb powder)
29.6% (35 fewer shots per lb powder)

6.5 CM (22") - 140 Accubond, 42.5gr RL16, 2,760 fps.

.270 Win (22") - 140gr Accubond, 62gr IMR 7977, 2,930 fps.

.270 Win (22") - 150gr SGK, 56.7gr RL23, 2,965 fps.

.270 Win (22") - 150gr NPT, 60.5gr RL26, 2,980 fps.

Powder increase from 6.5 CM to .270 Win for these loads respectively:

45.8% (52 fewer shots per lb powder)
33.4% (41 fewer shots per lb powder)
42.4% (49 fewer shots per lb powder)
 
Gtscotty said:
If a rifle in .270 I wanted was available in both 9 and 10 twist, I'd go with 9 no question, more bullet options, no downside.
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Absolutely. Winchester made a horrible mistake making a round between the 6.5mm and 7mm, but choosing a twist rate way slower than what Mauser used for either (1 in 200mm and 1 in 220mm respectively). Winchester just literally didn't know what they were doing, and thought they were making a varmint/medium game crossover round rather than a medium/big game round. It's unfortunate, because there's nothing inherently wrong with the bore diameter, but by being ignorant and picking the wrong twist, Winchester crippled the round in ways it doesn't seem able to recover from. I hope the Fieldcraft rifles will help, but they're such a small percentage of rifles sold I doubt it will.
 
Winchester designed such a poor round tuned for too light of bullets to the point it looks like the .270 Win may never recover?

Is this the twilight zone?

I comprehend ballistics and twist ratio vs bullet weight but that's where you keep losing me every since this topic came up. The .270Win isn't a PRS or benchrest round, I'm sure most everyone agrees, but it almost seems like a couple of folks here think that there's nothing else a rifle can be good for if not 1,000yd competition.

It's a hunting round. Within the distance most hunters are willing to shoot, the heavy sleek bullets are not necessary. The weight range the .270 Win covers are a great weight range for coyotes to elk and being nearly perfect for the hog-whitetail and mule deer size game. Its a popular range of critters to hunt. So much so its been one of the top selling rifle cartridges every year for decades after decade for nearly a century.

The "may never recover" thing sounds like me telling you, Sam Walton picked a horrible business plan and Walmart may never take off. I follow why it's not the round for you but there's a ton of folks it falls just right for. It and several other rounds that cover that same list of animals perfectly. It's been a VERY successful design.
 
Llama Bob said:
I'm aware of that. The real reading were in the low .5s due to lack of stability. That would be OK by itself, but it indicates the bullet would keyhole if atmospheric conditions became much worse.
Click to expand...

I've been hunting with 150gr ABLR in my 270 and it's Lilja barrel. I'm 1.64 stability with my 270 using new Nosler data SD is 279 How would that bullet keyhole. If you used new data post results. Your old post was based on 1.1 or 1.2 stability.
 
TN Outlaw said:
Winchester designed such a poor round tuned for too light of bullets to the point it looks like the .270 Win may never recover?

Is this the twilight zone?

I comprehend ballistics and twist ratio vs bullet weight but that's where you keep losing me every since this topic came up. The .270Win isn't a PRS or benchrest round, I'm sure most everyone agrees, but it almost seems like a couple of folks here think that there's nothing else a rifle can be good for if not 1,000yd competition.
Click to expand...

It might be the preferred style today, but if they had offered it way back when with a faster twist and only 160 gr long-range bullets, it wouldn't have become anywhere near as popular. Back before laser rangefinders, heavy bullets meant only a lower effective range in the hunting field. You couldn't even buy any ELD-type hunting bullets in 1925. And you could kill anything in North America well past the range most people would kill anything with 130-150 grain cup-and-cores.

It's like saying the Ford Model A was a bad design and Ford didn't know how to make a car because the Model A didn't have power steering or seat belts.
 
I have been picking up shed antlers, watching a beautiful gold colored moon come up and set each day, and listening to the coyotes howl just before dark. That is the real world. This bashing of the 270 Winchester is a make believe world created by people who don't have anything better to do.
 
TN Outlaw said:
It's a hunting round. Within the distance most hunters are willing to shoot, the heavy sleek bullets are not necessary.
Click to expand...
For the elk hunter, heavy bullets are a darn good idea regardless of distance. A sectional density of around 0.3 in a premium expanding bullet is about what is required to get a pass-through on a big bull elk from all reasonable angles The only bullets with that kind of sectional density in .277 that will run in a 1:10" are round noses or quasi-round-noses like the 160 partition and 165 Oryx. All of those bullets are so blunt that they're not going to do you any good at all at range - you're probably limited to 250y or something.

So for the western hunter looking at non-infrequent 500y+ shots, the .270 offers you the options of poor terminal performance, or completely unacceptable long range performance. Which is why no one shoots them other than new hunters who show up with their deer rifle. Move up 7 thousandths to a 1:9 or 1:9.5" .280 (probably AI at this point), and all your problems go away and you can shoot the 175gr Weldcore or several other options.
 
Goosey said:
It might be the preferred style today, but if they had offered it way back when with a faster twist and only 160 gr long-range bullets, it wouldn't have become anywhere near as popular. Back before laser rangefinders, heavy bullets meant only a lower effective range in the hunting field.
Click to expand...
Ridiculous blather. The advantages of high-BC bullets were understood going all the way back to the first hunting loads for the 7mm Mauser and further back to the military loads for the Lebel. Winchester was simply ignorant of information that was already well understood in Europe. And there's nothing keeping you from shooting light bullets in a fast twist rifle if you want, but the other way around doesn't work. A fast twist rifle is simply superior.
 
Llama Bob said:
So for the western hunter looking at non-infrequent 500y+ shots
Click to expand...

I'm not going to claim to be an experienced elk hunter by any means, but I have hunted elk in Colorado 4 times. Every elk killed on those trips, and shots taken for that matter, have been 400 yds., or less. Any ethical hunter knows his limitations, and that has been debated on this board many times. Maybe some people wouldn't shoot at 500+ yards no matter what rifle they choose. I agree with their decision.

Llama Bob said:
Ridiculous blather
Click to expand...

Yes, please stop.
 
Laphroaig said:
I'm not going to claim to be an experienced elk hunter by any means, but I have hunted elk in Colorado 4 times. Every elk killed on those trips, and shots taken for that matter, have been 400 yds., or less. Any ethical hunter knows his limitations, and that has been debated on this board many times. Maybe some people wouldn't shoot at 500+ yards no matter what rifle they choose. I agree with their decision.
Click to expand...
It depends completely on the unit, but most places first season the elk are above tree line, and they're not particularly interested in letting you walk up to them and there's not much to hide behind for a stalk. If you're unwilling to take long shots, you will get a lot fewer elk. Many units the area above treeline is largely public land, while the forested areas hunted 2nd and later season are private, so that factors into it as well. And of course 2nd and later season are OTC zoos on public land.

People are certainly welcome to use whatever they want within the law, but all elk rifles are not created equal. There are very obvious mechanical advantages to some cartridges and calibers and pretending otherwise is just ignorance.
 
Gtscotty said:
Barrett is putting 9 twist barrels on their .270 Win Fieldcraft rifles in 2019, which would be nice if you want to shoot the longer 150gr bullets. I never did get the accuracy I was looking for in my .270s with 150gr bullets longer than the NPT and SGKs, I suspect the 10 twist was my limiting factor as the rifles shot much better with pretty much every shorter bullet I tried. If a rifle in .270 I wanted was available in both 9 and 10 twist, I'd go with 9 no question, more bullet options, no downside.

The 25% increase in powder going from a short action cartridge to a long action referenced here is somewhat accurate for .308/.30-06, but is too low for a 6.5CM/.270 Win comparison.

Actual loads I use or have used in the past:

.308 (20") - 178gr ELDx, 43.8gr Varget, 2,590 fps
.30-06 (22") - 180gr Accubond, 56gr H4350, 2,800 fps.

.308 (22") - 165gr SGK, 45.5gr Varget, 2,750 fps.
.30-06 (22") - 165gr SGK, 59gr H4350, 2,920 fps

Powder increase from .308 to .30-06 for these loads respectively:

27.8% (34 fewer shots per lb powder)
29.6% (35 fewer shots per lb powder)

6.5 CM (22") - 140 Accubond, 42.5gr RL16, 2,760 fps.

.270 Win (22") - 140gr Accubond, 62gr IMR 7977, 2,930 fps.

.270 Win (22") - 150gr SGK, 56.7gr RL23, 2,965 fps.

.270 Win (22") - 150gr NPT, 60.5gr RL26, 2,980 fps.

Powder increase from 6.5 CM to .270 Win for these loads respectively:

45.8% (52 fewer shots per lb powder)
33.4% (41 fewer shots per lb powder)
42.4% (49 fewer shots per lb powder)
Click to expand...

Not to digress - but that is a smokin' 150 gr. NP out of a 22" Bbl.

2,980 fps...?

Yikes!

Usually stuff 55 gr. of IMR 4831 and get a very accurate ~ 2800 fps load. (as compared to 44 gr. RL-19 for the 6.5CM/140 gr. NP )

Have been reading about RL-26, but have yet to see any .270 Win. data until now.

Any down-sides to that load?

(Thanks for the post.)




GR
 
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Llama Bob said:
For the elk hunter, heavy bullets are a darn good idea regardless of distance. A sectional density of around 0.3 in a premium expanding bullet is about what is required to get a pass-through on a big bull elk from all reasonable angles The only bullets with that kind of sectional density in .277 that will run in a 1:10" are round noses or quasi-round-noses like the 160 partition and 165 Oryx. All of those bullets are so blunt that they're not going to do you any good at all at range - you're probably limited to 250y or something.

So for the western hunter looking at non-infrequent 500y+ shots, the .270 offers you the options of poor terminal performance, or completely unacceptable long range performance. Which is why no one shoots them other than new hunters who show up with their deer rifle. Move up 7 thousandths to a 1:9 or 1:9.5" .280 (probably AI at this point), and all your problems go away and you can shoot the 175gr Weldcore or several other options.
Click to expand...

Hunt out West quite a bit - and can count the shots I've made > 500 yards? ...on my antennae.

(Course, don't use fish-finders when fishing, or laser range-finders when I hunt, although, for ethical reasons, and the now reasonable cost, am considering one)

Top of back hold at ~ 350 yds, daylight hold past that, and anything longer falls short.

Hunting - as opposed to shooting.

So, what difference does high twist-rate make?




GR
 
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