404 J Twist Rate

[Fastrig]

With a 404 Jeffery, you are most likely going to shoot either a 400 grain bullet or a 400 grain bullet. Velocity will be around 2300 FPS. For a Swift A Frame bullet and using the formula from @Mekaniks post (which I believe is known as the Greenhill Formula), I ran some numbers (hey, I'm an Engineer).

The number crunching suggests a 1-19 twist rate will work, a 1-16 is good and a 1-10 is probably more than you need.



View attachment 294203


TWIST RATE = (0.423^2 x 150) / 1.380 = 19.45


Running a 1-19.45 Twist Rate on the JBM Calculator

View attachment 294204
Output Data

Stability

The Miller stability value. It should be between 1.3 and 2.0 to ensure stability (the military uses 1.5).



Calculation using 1-16 Twist Rate

View attachment 294205



Calculation using 1-10 Twist Rate

View attachment 294206

Wow!! Okay, I'm no ballistic guru by a long shot and I'm looking for a baseline/reference-line here....is the stability factor better as it gets higher or lower? Guessing higher is better, within reason. So if Montana Rifle company is putting out a 404J with 1-12 twist, is that overkill or just a very good rifling for stability? Love this education stuff...thank you!!

 

[Fastrig]

Thaat's what I love about AH. Got a question, someone's got an answer and is more than happy to share it. I've learned so much here that I could never have found on my own. I'm amazed at the breadth of experience and knowledge available on so many subjects.

Dittos on that....I'm learning a ton on AH....love it!!

 

[375 Ruger Fan]

More than you ever wanted to know about twist rate: See attached

 

[Fastrig]

More than you ever wanted to know about twist rate: See attached

Crap, I'm back in math class

Thanks for these, I'll read through them....hope you aren't going to send a quiz though

 

[Shootist43]

Fastrig, I have two 404 Jeffery caliber rifles, one with a 1/10 twist the other with a 1/16 twist. Both shoot MOA or better with the same load. That being 400 Gr. Swift A Frames at 2300 FPS.

 

[Fastrig]

Fastrig, I have two 404 Jeffery caliber rifles, one with a 1/10 twist the other with a 1/16 twist. Both shoot MOA or better with the same load. That being 400 Gr. Swift A Frames at 2300 FPS.

Thank you. Sounds like anything between 1.10 to 1.16 twist is fine for the 404J.

 

[Gert Odendaal]

I concur, every 404 Jeffery rifle with a good , sound barrel/grooves will shoot a 400 gn bullet very , very accurate ...mine is a tack driver with open sights as well as scope...it shoots much, much better than what I am capable of shooting...

 

[Fastrig]

I concur, every 404 Jeffery rifle with a good , sound barrel/grooves will shoot a 400 gn bullet very , very accurate ...mine is a tack driver with open sights as well as scope...it shoots much, much better than what I am capable of shooting...

Kind of off topic here, but what is the effective range of the 404J? It's obviously designed for a heavy punch on big game at closer ranges, but how far out is it legitimately effective for larger plains game, i.e. Kudu and up? Guessing a couple hundred yards, maybe as much as 250-300 with the proper load? I'm not planning on using it in this manner, just curious how flexible the rifle is. For PG 300 yards and in I'm planning on using my Mauser 9.3x62 and if I need to get out further than that then I'd be taking a 300 or 338 win mag.

 

[Gert Odendaal]

Most owners of a 404 Jeffery are hunters who do walk and stalking on dangerous game or plains game ...I know the 50o Jeffery is renowned to shoot a 500gn bullet accurately out to 250 meters....the 404 Jeffery I do not know..

 

[Fastrig]

Most owners of a 404 Jeffery are hunters who do walk and stalking on dangerous game or plains game ...I know the 50o Jeffery is renowned to shoot a 500gn bullet accurately out to 250 meters....the 404 Jeffery I do not know..

Walking and stalking is much how I hunt as well....betting out to 250 with a 404J is probably doable as well. Thanks.

 

[tarbe]

One thing to remember. The denser the medium that a bullet is traveling through, the faster the twist needs to be to maintain stability.

What is denser, air or a buffalo?

So my point is, what is optimal for accuracy while shooting targets is not necessarily optimal for bullet stability during penetration...Especially if the bullet in question does not shorten significantly during penetration.

 

[nztimb]

Kind of off topic here, but what is the effective range of the 404J? It's obviously designed for a heavy punch on big game at closer ranges, but how far out is it legitimately effective for larger plains game, i.e. Kudu and up? Guessing a couple hundred yards, maybe as much as 250-300 with the proper load? .

Ballistics expert Keith Luckhurst ran some trajectory tests comparing a .404 Jeffery loaded with 400-grain bullets at 2280 fps, a .458 Winchester Magnum loaded with 500-grain bullets at 2090 fps, and a .375 H&H leaded with 300-grain bullets at 2550 fps, all sighted in at 100 meters. According to Luckhurst, “At 250 meters the .375 Magnum has dropped 11 inches, the .404 has dropped 13 inches and the .458 has dropped 18 inches. But at 150 meters there is a spread of only one inch between these calibers, and at 200 meters it is four inches. Most gunwriters would describe the .375 Magnum as flat shooting and the descriptions of the .458 tend to include words like ‘rainbow trajectory.’ In reality, the point of aim for any of the rifles is virtually the same out to 150 meters.” Luckhurst concludes that the .404 Jeffery, with better penetration and less recoil than the .458, a trajectory almost as flat as the .375 H&H, and overall performance similar or equal to the .416 Rigby, is a particularly well-balanced rifle for the largest and most dangerous game.

 

[Hogpatrol]

PacNor barrel's website lists a 14" twist as the most popular and one of two twists they manufacture in that caliber. The other is a 9", three groove.

 

[Fastrig]

PacNor barrel's website lists a 14" twist as the most popular and one of two twists they manufacture in that caliber. The other is a 9", three groove.

Sorry for the ignorant question here, just trying to learn. The 14" twist, based on all the great info folks have been providing, makes sense but what would be the advantage/disadvantage of the 9", three groove twist? When I've bought rifles I've always looked at the average twists most manufactures are offering and assumed they were providing rifle twists "that worked best" for the given caliber and barrel length, and they are normally all within a couple of inches of each other. Based on all the great input on this thread I'm seeing twists now from 9" to 16", which seems to be a pretty wide margin as to what I've normally looked at on other calibers, though those have all been medium and small bore guns (under 375).

 

[Gert Odendaal]

PacNor barrel's website lists a 14" twist as the most popular and one of two twists they manufacture in that caliber. The other is a 9", three groove.

I suggest you look at Shilen barrels as well..I bought one with assistance of Butch Lambert here on the forum..it looks to be a great barrel....at a great price as well...I bought a PAC-NOR barrel as well..will see how it performs,,,it just seems the Shilen Barrel has a smoother finish, it has a caliber punched on the chamber end , with a serial number...which I asked PAC -NOR to do as well but they declined...the reason I asked is in South Africa when importing a barrel it has to have a serial number on it..a Permanent Import number...you use as a number to register the barrel on the system..this is suppose to be so..I will still have to go through the registering procedures when completed the rifle build and see if the theory meets the practical end result...

 

[Hogpatrol]

I assume a 9 twist is for shorter, lighter weight bullets. Krieger's website shows their barrels for the 404J in only a 16 twist.

https://kriegerbarrels.com/twist#bolt

 

[Hogpatrol]

I assume a 9 twist is for shorter, lighter weight bullets. Krieger's website shows their barrels for the 404J in only a 16 twist.

https://kriegerbarrels.com/twist#bolt

I meant heavier and longer bullets for the 9 twist. I don't know how heavy of a bullet can be used in the 404J, possibly the monolithic brass or solid copper types would require a 9 twist.

 

[bruce moulds]

staying stable in flesh and bone requires a faster twist than in air.
a good example of this requirement is in 45 cal.
550 gn bullets will stay stable out to 1500 meters and beyond, but the 458 magnums of today run much faster twists for 500 gn bullets.
faster twists cause soft points to expand faster, either a good thing or bad, depending on the application.
in the case of the 404, 9" or 10" twists might well be faster than needed.
12 to 14 sounds good.
some of these modern fast twist barrels are for heavy for calibre long range monolithic vld bullets.
pacnor and shilen barrels are in the same quality class. also Krieger. none of these is a bad choice.
in response to the comment about a rifle being a tack driver with iron sights.
anyone who can establish this on a statistical basis must have very good eyes, coordination, and just the right target to match the sights.
tack driving in air is of less importance in a 404 than the bullet remaining point on during penetration.
as I write this, I have come to the conclusion that I would seek out a 12" twist if easily done.
especially if trying to drive a solid through feet of bone.
the solid should not shorten, and will benefit from a twist not too slow.
bruce.

 

[Fastrig]

staying stable in flesh and bone requires a faster twist than in air.
a good example of this requirement is in 45 cal.
550 gn bullets will stay stable out to 1500 meters and beyond, but the 458 magnums of today run much faster twists for 500 gn bullets.
faster twists cause soft points to expand faster, either a good thing or bad, depending on the application.
in the case of the 404, 9" or 10" twists might well be faster than needed.
12 to 14 sounds good.
some of these modern fast twist barrels are for heavy for calibre long range monolithic vld bullets.
pacnor and shilen barrels are in the same quality class. also Krieger. none of these is a bad choice.
in response to the comment about a rifle being a tack driver with iron sights.
anyone who can establish this on a statistical basis must have very good eyes, coordination, and just the right target to match the sights.
tack driving in air is of less importance in a 404 than the bullet remaining point on during penetration.
as I write this, I have come to the conclusion that I would seek out a 12" twist if easily done.
especially if trying to drive a solid through feet of bone.
the solid should not shorten, and will benefit from a twist not too slow.
bruce.

The Montana Rifle Co. 404J has a 12" twist...it's one of the options I'm considering. Thank you for the info, greatly appreciated.

 

[Shootist43]

Fastrig, when I bought my second 404 Jeffery and found out that it had a 1/16 twist rate I was concerned since the other rifle I had was 1/10. I did the minimal twist rate calculation and discovered that it was higher than the twist rate in either of my rifles. The "optimal" twist rate for any given caliber probably depends on which bullet is being used.