Can a 100 gr Bullet Stabilize from a 1955 .244 w/ 1:12" Twist?

[pgtr]

EDIT: Made changes to comply with posting policy

In my previous post I queried about the possibility of loads for a 95 grain bullet. I’ve got an old Remington 722A from 1955 chambered in .244 (6mm Rem) with the earlier 1:12” twist.

Since then some clues have emerged that not only could a 95 grain bullet be used, but in fact a 100 grain bullet. Let’s review:

• The original Remington #1244 90 grain factory ammo is described as pointed, soft point, flat based and it certainly shot accurately.
  
• The Speer #1217 Hot Cor 90 grain bullets I’ve handloaded is, in my experience, shooting very accurately. I would describe the bullet as highly similar to the original Remington in outside appearance.
  
• Nosler 90 grain purple tipped bullets out of a generic white box, bought as ‘reloaded’ ammo from a gun show were also found to be accurate. What’s interesting about this bullet is it’s a boat tail and thus longer than the flat based fare tried earlier.
  
• Finally a box of Federal Premium Nosler Partition 100 grain factory ammo would NOT stabilize. (Correction - while not a boat tail - it's a fairly long bullet configuration)

This suggests that the bullet grain limits for this particular rifle lay somewhere north of 90 and possibly has high as 100 depending on bullet configuration (notably length).

To start with I applied the Miller Twist Rule Formula. Specifically I solved for 's' or 'Stability Factor' as can be seen here https://en.wikipedia.org/wiki/Miller_twist_rule.

Likewise the online Berger Twist Rate Calculator may be handy for you and refers to the same calculation as 'SG'. However it's a bit clumsy for crunching larger data sets. So I created a spreadsheet using the formula and achieved essentially the same results.

The Speer 90 grain produced a stability factor of 1.27. The Berger online calculator corroborated my calculation.

For comparison sake, the Federal Premier that I had tried with Nosler Partition 100 grain only had a factor of 1.06 which was decidedly NOT stable in theory or practice!

With a spreadsheet created it became relatively easy to load in tabular data for a variety of 90 to 100 grain bullets. Using the 1.27 factor from a known stable bullet (and 1.06 being very unstable) - a few interesting observations stood out…

Most of the 95 and 100 grain bullets produced SG calculations well below my known to function 1.27 baseline - down closer to 1.06 or so - not particularly confidence inspiring. But a couple bullets did stand out.

The discontinued Hornady Round Nose #2455 in 6mm calculated to be 1.36 - suggesting it might be MORE stable than the proven Speer Hot Cor #1217 90 gr. But unfortunately it’s no longer on the market.

And finally the bullet that was the most interesting was the Norma Oryx #20660501 6mm 100 gr bullet. It calculated to be 1.24 - tantalizingly close to my proven 90 grain Speer load! I would describe these as somewhere between a round nose and a point with a flat base and subtle chamfer (see image below). As luck would have it - a major online retailer had the Normas on sale and so I picked up a box. By the time I’d worked up to 35 grains of IMR4064 powder, they grouped very well at both 100 and 200 and I could use the same zero on my scope as with my Speer Hot Cors. I left it at that.

So, yes, the slow 1:12” twist of my venerable 1955 722A .244 can indeed effectively shoot a 100 grain bullet (if chosen carefully) just like it’s modern 6mm Rem and .243 Win cousins!

What next? I may experiment with 95+ grain boat tails with polymer tips. I’m thinking the polymer tips don’t ‘count as much’ against overall length due to the lack of relative mass. And I may also work up a varmint load and perhaps even a target load. All part of the hobby.

 

[Jim Watson]

An old Gun Digest or Handloader's Digest article suggested cutting off the exposed lead nose of a 100 gr JSP back to the edge of the jacket. Kind of like the old "protected point." The author said this shortened the bullet enough to shoot well in his 12 twist .244.

Sad to say, the Nosler 100 gr semi-spitzer and Speer 105 gr roundnose are no longer in production.

 

[gw44]

Well norma bullets are good bullets, and you put in the time to prove that and they shot out of your 722 1:12" twist rifle, thank you for sharing your findings !!!

 

[ThomasT]

I was going to mention the old Speer round nose bullets. I have one unopened box left. Too bad everyone thinks you can only hunt and kill with pointy bullets. It’s been my experience that round nose bullets are far easier to get good accuracy with without a lot of load work up.

Do yourself a favor and try some IMR 4350 powder. I am surprised no one has mentioned it before now. My Speer #10 manual recommends 42 grs for a start load and 46grs for a max with 90gr bullets and 39/43 with 100 gr bullets.

Get an RCBS case forming die and you can make all the brass you need from 270 & 30/06 brass. That’s how I get most of my 7&8mm brass.

 

[bamaranger]

Federal Premium Nosler Partition

Isn't the Nosler Partition a flat base bullet........in all calibers?

 

[pgtr]

Isn't the Nosler Partition a flat base bullet........in all calibers?

It is - at least I would call it flat based essentially.

However it's still a fairly long bullet too - probably due to the bit of copper in the core elongating it...? According to my calculations - it's stability factor is only 1.06 which would not predict it to be stable at all.

I picked up a box of Federal (see gold box below) back around 2000 or so (still have original box pictured below) which was factory loaded with 'Nosler Partition' bullets in 100 gr. It was NOT stable at all in application!

For comparison the Norma Oryx 100gr is only 0.980 long which according to my implementation of the Miller formula produces a stability factory of 1.26 and that makes all the difference in the world!

 

[pgtr]

Things were a great deal different in 1955. Remington loaded .244 Rem ammo with 75, 90 and 100 grain bullets and used the 1 in 12 twist. The issue was that Joe Public had been taught that that just wasn't right. So he didn't buy Rem M722's. The rest of it is moot.

Remington did not offer 100 grain factory loaded ammo in .244 in 1955. They only offered 75gr and 90gr. That was the case for the next 7 years.

Remington first offered 6mm 100 grain factory loaded ammo (Cor Lokt) in 1963 in conjunction with the Model 700 6mm. At the same time they also offered 75 and 90 gr but still labeled it ".244".

Perhaps the "6mm" label helped discourage owners of early .244 722s from purchasing 100gr ammo that wouldn't stabilize in their slower twist barrels. (though a '58 or later 722 did in fact have the faster twist)

Miller Twist Rule Formula is his opinion. Has as much value as the Ladder Test and ballistics calculators. And there's no such thing as a "stability factor".

I'm not quite sure why it wouldn't exist? It's possible I may not be using the correct terminology. But I solved for 's' as found in the formula cited here. S was described as "gyroscopic stability factor".

The Berger Twist Rate calculator also uses the same term "Stability Factor" but abbreviates it "SG" rather than "s".

It's certainly been very valuable to me: By spending a short amount of time gathering bullet specs, plugging them into my spreadsheet and solving the predictive stability factor calculation ... I found a great shooting Norma Oryx in 100gr.

Thanks for your comments

 

[hdwhit]

pgtr wrote:
This suggests that the bullet grain limits for this particular rifle lay somewhere between 90 and possibly has high as 100 depending on bullet configuration.

Keep in mind that what determines whether a particular twist rate will be able to stabilize particular bullet is not dependent upon the bullet's weight, but its length. In the case of gilding metal jacketed lead bullets of a given diameter, the only way to make the bullet heavier was to make it longer, so weight became an effective proxy for length. But now that we have bullets with steel inserts, plastic tips, composite construction, and lead-free construction, the relationship between weight and length no longer applies, so it must be recognized when considering twist rates that what matters is not bullet weight, but bullet length.

 

[Unclenick]

Pgtr,

I must have deleted Mr. O'Heir's post as bad information while you were composing. I'm sure he has no idea that Miller simply refined the venerable Greenhill formula nor that physicists and aerodynamicists who work out a way to describe influences on an object speeding through air get to name that description whatever they want and thereby cause it to exist.

Keep in mind that what determines whether a particular twist rate will be able to stabilize particular bullet is not dependent upon the bullet's weight, but its length.

Actually it's the combination of the two, but the effect of length increases with its square, where the effect of mass is merely proportional, so length is the dominant influence.

For example, suppose you cast two bullets in the same mold, one of pure tin and the other of pure lead. They will be the same length (for all practical purposes) but the lead bullet won't have to spin as fast to be stable at the same velocity. This is because the greater mass has more inertia, making drag work harder to turn it a given amount in a given amount of time. Since drag is proportional to the square of the sine of the angle of yaw of the bullet, reducing it even a little mitigates how hard the air is acting to produce the overturning moment.

 

[Stats Shooter]

The old 6mm with a 1:12 Twist was dubiously dubbed "The wounded of deer" for its difficulty with 100 gr .244 bullets according to some articles I read about it. I currently have a 6mm Remington Ackley improved in working on.

Anyway,
There is upshot to having a slower twist barrel which is the accuracy with which it pushes lighter faster bullets. Some fellas get their 6mm Ackleys with 1:11 -1:12 twist barrels so that they can push a 75 gr bullet very fast and more accurately than a 100 gr bullet.

Which begs the question: why not get a 1:8 twist and just shoot the 75 gr bullets? I haven't the data myself, but one accepted theory is that for the most precision, you want a Miller twist of 1.4, no more no less. When you are shooting groups in the 1's or 2's, this apparently matters.

So, you can do a bunch of things to try and get the bullets to stabilize, or develop a screaming 75 gr load....or get it rebarreled to your desired twist.

But if it were me, I would develop a varmint cannon.

 

[pgtr]

Given a choice a few years back I probably would have simply bought a .243 Win and done nothing more than buy the occasional box of 100 gr factory ammo as needed and been content.

But now that this .244 kinda 'forced' me into hand loading - I'm really enjoying it. It's added a whole new dimension to hunting.

My only real original goal was to develop a competent deer hunting rifle with my great uncle's .244. The 90 grain load I've developed does this nicely - much like the original ammo offered by Remington did 70 years ago.

You can see the bucks I've gotten (so far) here with my 90 grain load.

...yeah I could stick a fork in it and call it done. But nah... Developing the 100 gr load was just plain fun and a pretty cool success. I also do plan on developing a 75-ish grain varmint load and also spending more time bench shooting, longer ranges maybe. Heck - I've probably got years of projects ahead of me!

FYI I've used mostly new Hornady brass (150 pieces) but also have 40 Remington brass (20 was bought already reloaded so I don't know it's history) and 20 Federal brass. I picked up a Lee Challenger kit and die set and a few gizmos. (I don't seem to be getting much work done on my old car or tractor these days - I wonder why?)

Thanks all for your comments - looks like a great forum to share successes (and failures) on!

 

[old roper]

At one time I used to shoot Rem 40x's. I order 40X, 6 Rem Rangemaster for custom shop and one options was 1/10 or 1/12 twist barrel and I got 1/12 twist barrel @ 26". Back then they furnish test target with 2-5 shot groups and loads used. Target I got both groups in the .3's using 80gr, 36gr/IMR-3031,Rem case/primer. Back then Rem made 80gr PTD.SB also 80gr HP. I shot lot of varmints with the 40x using Rem 80gr HP.

Rem also chambered 6x47 in 40XB and offered it 1/12 twist barrel.

https://www.midwayusa.com/product/1...-6mm-243-diameter-80-grain-pointed-soft-point.

IMR used to have put out Handloader's Guide and it has 6 Rem data using 80gr/100gr Remington bullets.

I still have some Rem 80gr HP. My 243AI used to be 6RemAI short action and I also shot 6RemAI long action for the VLD.

If your using Berger twist calculator you understand what Marginal Stability means.
Well good luck

 

[mavracer]

My only real original goal was to develop a competent deer hunting rifle with my great uncle's .244. The 90 grain load I've developed does this nicely - much like the original ammo offered by Remington did 70 years ago.

Actually some of the modern 85-90gr bullets probably work better on deer than the old 100gr round nose/semi Spitzer bullets ever did.

 

[F. Guffey]

I still have a few 244 cases, I had a friend that had a personal friend that was a barrel maker, he called the barrel maker, the answer was no problem, right away, I will go back and select a barrel and get it in the mail today etc.. It got worst. He had had to take last years rifle to the next years prairie dogs hunt.

F. Guffey

 

[OSUCowboy67]

I have a Savage .243 with 26 in. heavy barrel in 1 - 12 twist. It is by far my most accurate rifle as long as bullets weighing 95 gr. and under are fired. At one time, a friend gave me several hundred 100 to 105 gr. bullets, and I found no way to get accuracy with those weights after many variations in how they were loaded, so the bullets were given to a reloader whose rifle liked heavier bullets. However, I have seen no problems with using bullets with weights of less than 100 gr., as 95 and 90 gr bullets are just as deadly for me.