I'm sure this subject has already been covered, but I'll bring it up again anyway!
I'm in process of planning a 375, possibly a 375Wby if they ever get the ammo/cases available!
I want to use premium soft points in 270gr to enhance the long range potential. Of course, a few 300gr softs and solids will be used now and then BUT the main focus here is for a long range big hitter for elk/bear in the states.
I'm wondering if the standard 375 twist rate is optimal for this application? I know that for solids a faster twist has shown better results in the big 45s, wonder if it applies here, especially if 270gr bullets will be the predominate weight?
Any comments or advise will be appreciated!

[This message has been edited by John S (edited 10-27-2001).]

John S,
I have thought about this too. I have concluded that the standard 1 in 12" twist is the best all around, especially if you are using high velocity 270 grain loads, and even for the 300 grainers at 2700 fps or higher, it is the best. IMHO, FWIW, free of charge.

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RAB

John,

The 1 in 12 twist for 375 is about the same as a 1 in 10 for 30 caliber, so the 1 in 12 in the 375 Wby is a very similar setup to the 1 in 10 when using a 30/06 as velocities are about the same.

If the goal was to get the most accuracy from the widest range of loads etc. then the 375 would, as is the 30/06, 308, 300 Win etc., be better served by a slower twist like 1 in 14 or 1 in 15 twist.

Having said that, to see any real differences between a 1 in 12 and say a 1 in 14 or 15, you would need to have that 375 Wby/Imp in a bench style rifle.

Mike

Mike-
It actually isn't the accuracy I'm after, it's the higher rotational velocity that will cause the bullets to expand more violently, hence an increase in devastation to the vitals!
I seem to remember Andy talking about this when he posted about his various testing.

John,

Yes, I remember some of Andy's comments. I think some were do with penetration on solids as well.

You will of course be loading the bullet up with more centrifugal force just from your extra velocity.

I think it will also vary with different bullets and calibers.

For what ever it is worth, I have shot heaps of roos and pigs with the 100 grain Hornady 270 from both 1 in 10 and 1 in 12 and also the 130 Speer Hollow point from 1 in 10 and 1 in 12 in the 308 at just under 3000 and 1 in 10 in the 30/06 at just under 3300.

There was no difference between the 270s and no differene between the 308s BUT the 30/06 was not as good and that was using bullets from the same boxes as the 308s were using.

However in the 375 the bigger diameter alone will increase centrifugal force for the same rotational velocity as the smaller bores and perhaps having a 1 in 10 instead of a 1 in 12 might just mean passing through a threshold.

Mike

John S ......take a look at the ballistic and trajectory tables for both the 260/270 gr and the 300 gr bullets in .375. I think you'll find the 300 gr does the better job of delivering energy at a distance and doesn't drop a lot more than the 260/270 gr.

John S,

For what it is worth and I am no expert with regard to 375, but I would opt for the 1 in 12 twist.

Todd E

Personally I also favor the 260 & 270 bullets in 375 as they give less recoil and for elk have more than enough energy at longer ranges.

You might check with the barrel makers and see what they recommend for your application.

Their websites usually give the info.

Let us know what you find out as some of us plan to rebarrel with the 260 & 270 bullets in mind.

Thanks everyone for the comments. I will continue to pursue this and will post whatever I find. If anyone else has some ideas or comments, please join in!

Some older 375 H&H rifles have twist rates at one in 14" and we should credit the originators of the caliber with more savvy than what we sometimes do. At one in fourteen, the optimum length of bullet for decent penetration indicates a jacketed lead, round nose solid, of 300 grains, or a jacketed lead spitser of 270/280 grains. One can use a jacketed lead solid of up to 350 grains in one in fourteen, and flight will be stable, but the risk of tumbling on impact increases, as the length of the bullet increases beyond that of the 300 and 270 grain bullets. This is why some experiments on penitration reported here from time to time, found that increased twist rates improve penetration. Logically, if the twist rate is fixed (you have bought the rifle), penetration will be more reliable with bullets shorter than what is required for stable flight. Newer 375s are mostly one in twelve and will stabilise jacketed lead bullets up to 380 gr in flight. The trouble starts when they strike the target, and the risk of tumbling increases. Bullets with too little gyroscopic stabilisation will not always tumble on impact, but using slightly shorter bullets than required, is good insurance against that kind of failure. I would rather have assured, linear penetration of a certain depth than possibly more with the risk of vastly less attached to it. Take a one in twelve twist and keep bullets to 300 grains in jacketed lead and 270 in monometal. In this case speed is worth more than weight.

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Gerard Schultz
GS Custom Bullets

John, log on to Weatherby's website at www.weatherby.com

I just came from there, and I found that .375 Weatherby factory ammo is now listed as available and loaded with 300 gr. Nosler Partition bullets, and that Norma .375 Weatherby brass is also listed as available.

According to Weatherby's rifle specs, the .375 Weatherby Mark V comes with a 1-12" twist.

AD

Gerard,
I hope you aren't getting cold feet on the 300 grain .375 HV and FN. If you do, I will be stuck with X-Bullets.

You have not mentioned the greater velocity of the big magnums producing greater RPM's for a given twist rate over the standard .375 H&H. This ought to offset any tumbling tendency of the heavier bullet, which is still a lightweight to me, and might be going 3000 fps, especially with the HV and FN wonder bullets.

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RAB

When you go for the 300 grainers, give the Sierra bullet #3000 a try. I just shot few for testing the other day from my .378. They clocked around 2965fps. Penetrated an average of 14" of wet newsprint at 25 yards. Consistent 66% weight retention, all three rounds. Expansion to around .75", beautifull mushrooms. I will try to post a pic in a day or two. I was extremely impressed, considering the velocity and that these are not bonded premium bullets. Will do test at 100 yards next time, I had been shooting all day and was pressed for time.

Ron,
A twist / bullet length mismatch cannot be corrected with more speed unless it is much more speed. For example, if a .30 cal bullet is 3mm longer than what is correct for stable flight, you need 600 fps or more to correct it, sometimes more, depending on where you start. The higher the speeds, the more dificult it becomes. The bigger, slower calibers are not that critical as most have twist rates much tighter than required. It is the medium calibers (375) and smaller that are more fussy. A 300 grain 375 in HV will need a one in 13 and 2900 fps to work well terminally beyond 400.

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Gerard Schultz
GS Custom Bullets

What would the effect be if one were to use a 1x10 twist? Better and straighter penetration?
I mention this because I know of two people that use 375imp rifles with 1x8 twist barrels and they work wonderfully on anything they are pointed at! BTW, they shoot 250 and 275gr bonded core type bullets, which should do better from a slower twist, at least I thought they would!

[This message has been edited by John S (edited 10-30-2001).]

Never go with a borderline slow twist unless it's a bench rifle. Use the standard 12" twist and be done with it.

I think Browning or FN made some 14" .375 H&H's. I would avoid these.

I don't buy that argument that rotational velocity or engery matters much as far as transmittion energy or cutting flesh. Long ago someone came up with a line of Wildcats and I think that the twist was 5 1/2" and it was claimed that the cartridge (I think it was a 6.5) would be far more lethal.

I think I wrote to the maker and said that in a 15" thick animal that would make 3 turns! There was no reply. Of course if the bullet stopped in the animal all of it's rotaional would go to work.

Davis of the NRA wrote on this and calculated that the rotational energy was very low as a comparision.

Spining and cutting? Naw.

It's most important to concentrate on aiming. That's the most important variable.

Gerard,
Thanks for the reply. I guess you are finally going to get around to making the 300 grain HV and FN in .375 caliber. A new epoch begins! So if a 1 in 13" twist and 2900 fps will work, will not a 1 in 12" and 2900 fps work as well or better?

Don Martin29,
I agree that the buzz-saw/tissue-cutting/energy-transfer thing is BS. However, we are talking about possible marginal stability and penetration improvement with the faster twists. Aren't we y'all?

John S,
I guess that would be Andy, and who else, with the fast twist 375's?

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RAB

RAB-
Yes, Andy is one of the two mentioned! And yes, we are talking about directional stability at this point! I must agree that using a fast twist barrel to impart more spin and hence, more tissue damage is likely a flawed theory.

There is a further advantage to more spin than what is required just for stable flight. Should you nick something on the way to the target, a bullet that is borderline stable will tumble instantly. A bullet that is spinning faster than needed, is not so easily deflected and may may recover. Nicking something in mid flight is a recipe for disaster, but shorter bullets do better and it adds a further margin of reliability to the equation. When I say shorter bullets, take that as a 300 grain 375 mono in a one in twelve inch or a 40 grain 224 mono in a one in ten inch. "Buzz saw effect" is funny, I wonder who dreamed that one up.

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Gerard Schultz
GS Custom Bullets

RAB-
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