.222 Rem. Family

[South Pender]

357Mag, I agree that expansion ratio is not the entire picture. However, I'm wondering whether there is an ideal expansion ratio for each bore size with respect to accuracy potential. Probably not quite that simple, though. Perhaps case shape confounds this analysis, since the .22 PPC seems to be more inherently accurate than the .222 Rem. and its descendants while having a smaller expansion ratio than all but the .222 Rem. Mag.

One cartridge that I should have included in the original group is the .221 Fireball, another descendant of the triple deuce. Originally a pistol cartridge, it has achieved some popularity as a rifle varmint round. The Fireball would have the highest expansion ratio of these .222 Rem. derivatives. I wonder what the accumulated evidence on its accuracy reveals.

 

[Brians356]

The Fireball would have the highest expansion ratio of these .222 Rem. derivatives.

I think you mean Fireball has the lowest expansion ratio. For a given bore size and barrel length (given bore volume) the smaller case capacity has a smaller expansion ratio. High expansion ratios are more "overbore".
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[centershot]

I have and shoot all three. I had a 222 Rem mag made to shoot 55 gr varmint bullets as fast as I could since I have wind most of the time. Finding the brass was not easy. Nosler made some 222 Rem mag brass and it's primer pockets could take the pressure to a point, then loose. Could not get much over 3450 before pressure and loose pockets. I noted Lapua was making 222 Rem brass, so I had one chambered with some modifications...30° shoulder, case taper reduced to .010" and shoulder moved forward a bit. This is a killer!!! It maintained the accuracy of the original 222 and with LT 30 I can exceed 3600 fps with a 52 gr varmint bullet. Primer pockets start loosening if MV stays over 3600, so I tone it down to 3550. Less than 24 gr powder per firing so barrel should last a long time. My 223 is just not as accurate and requires more powder to get same MV as this modified 222.

I use LT-32 in my .222x35* Have you ever tried it? I have not tried LT-30. Is LT-30 slower or faster?

 

[lpreddick]

I use LT-32 in my .222x35* Have you ever tried it? I have not tried LT-30. Is LT-30 slower or faster?

LT 30 is faster than LT 32, about 1 gr faster, meaning 1 gr less than LT 32 to get same velocity you get with LT 32. I tried LT 32 but case got full before I got the velocity I wanted.

 

[South Pender]

I think you mean Fireball has the lowest expansion ratio. For a given bore size and barrel length (given bore volume) the smaller case capacity has a smaller expansion ratio. High expansion ratios are more "overbore".
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Brian, the definition of expansion ratio that I've seen is: ER = (volume of case + volume of bore)/volume of case. This is consistent with Homer Powley's use of the term. It means that the smaller case has the greater expansion ratio. As just two examples, both in .224 bore size, the 220 Swift has an ER of about 6.0 with a 24" barrel, whereas the .222 Rem. with 24" barrel has an ER of about 12.0.

 

[Brians356]

Brian, the definition of expansion ratio that I've seen is: ER = (volume of case + volume of bore)/volume of case. This is consistent with Homer Powley's use of the term. It means that the smaller case has the greater expansion ratio.

Well, then there is definitely a difference of expert opinion. Wayne van Zwoll, Ph.D., wrote in Shooter's Bible Guide to Rifle Ballistics (2011):

Expansion ratio: Interior case volume divided by bore volume. Cartridges with high expansion ratios are said to be "overbore capacity". That is, they have big powder chambers compared to relative to the bore size. Slow powders and long barrels are necessary to get the most from these rounds.
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[JRS]

Homer Powley was light-years ahead of his peers.

 

[South Pender]

Well, then there is definitely a difference of expert opinion. Wayne van Zwoll, Ph.D., wrote in Shooter's Bible Guide to Rifle Ballistics (2011):

Expansion ratio: Interior case volume divided by bore volume. Cartridges with high expansion ratios are said to be "overbore capacity". That is, they have big powder chambers compared to relative to the bore size. Slow powders and long barrels are necessary to get the most from these rounds.
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It would appear that van Zwoll has it backwards. Use of the Powley Computer yields higher ERs for smaller-capacity cartridges than for larger-capacity cases with the same bore size.

Here is the online version of the Computer based mainly on Powley's work, but also on contributions by Wm. C. Davis, Ken Howell, and Don Miller. Click on the underlined "This version" to get to the calculator:

http://kwk.us/powley_notes.html

Along with output on expansion ratios, it provides other internal ballistics information like pressure, efficiency, etc.

Also, consider P. O. Ackley's explanation in his Handbook for Shooters & Reloaders, Vol 1 (1962):

"Expansion ratio is the ratio between the total volume of the bore and the volume of the case. It is the number of times the gas will expand by the time the bullet reaches the muzzle. High expansion ratios mean good barrel life. Low expansion ratios mean short barrel life. Low ratios may result in the highest velocity but in many instances this slightly higher velocity is more than offset by greatly reduced barrel life...."

Finally, we have this from Wm. C Davis, Jr. in "Some Simplified Interior Ballistics for Handloaders," pp. 138-144 in Handloading, published by the NRA, 1981:

"R = (Q + U))/U,

where R = expansion ratio, Q = volume of bore, and U = volume of powder chamber."

This is seen in the example I gave above. I used the Powley Computer with loading data from the Nosler reloading manual for both the .220 Swift and .222 Rem. with 50-gr. bullet, 24" barrel, and similar pressures (around 51,000 CUP), and got: .220 Swift: ER = 6.0; .222 Rem.: ER = 12.1.

 

[Brians356]

Homer Powley was light-years ahead of his peers.

True. But Wayne van Zwoll wasn't Powley's peer. Powley is deceased, van Zwoll is still active (last I checked.) So, apparently as with many terms, definition evolves over time. It pays to outlast the other guy.
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[South Pender]

True. But Wayne van Zwoll wasn't Powley's peer. Powley is deceased, van Zwoll is still active (last I checked.) So, apparently as with many terms, definition evolves over time. It pays to outlast the other guy.
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The term hasn't evolved over time (and certainly wouldn't "evolve" to mean the opposite of its original meaning!). Van Zwoll just got it wrong. He's not a ballistician (like Powley and Davis) or cartridge expert like Ackley. His expertise is in big-game hunting and wildlife.

The Powley computer has been updated recently in its online version, so it should be considered as representing current usage. And regarding current usage, here's a 2014 discussion of the term:

Bore capacity & expansion ratio.. (n.d.) >The Free Library. (2014). Retrieved Aug 30 2017 from https://www.thefreelibrary.com/Bore+capacity+&+expansion+ratio.-a03578530

where they write:

"The "inefficient" smallbore magnums such as the .264 Win., 7mm Rem., and .300 Weatherby are all low expansion-ratio rifles, with ERs around 5 or 6. The smaller cartridges with more modest velocity potentials--.22 Hornet, .256 Win. Magnum, .222 Rem., etc.--rate much higher on the ER scale: from 12 to 15. They are more efficient in the sense that they extract more useful velocity and energy from each grain of powder, but they cannot deliver the sheer power of the low-ER cartridge."

Perhaps this should be a separate thread given the apparent misunderstanding.

We now return to our regular programming and consider the .222 Rem. family of cartridges....

 

[357Mag]

The term hasn't evolved over time (and certainly wouldn't "evolve" to mean the opposite of its original meaning!). Van Zwoll just got it wrong. He's not a ballistician (like Powley and Davis) or cartridge expert like Ackley. His expertise is in big-game hunting and wildlife.

The Powley computer has been updated recently in its online version, so it should be considered as representing current usage. And regarding current usage, here's a 2014 discussion of the term:

Bore capacity & expansion ratio.. (n.d.) >The Free Library. (2014). Retrieved Aug 30 2017 from https://www.thefreelibrary.com/Bore+capacity+&+expansion+ratio.-a03578530

where they write:

"The "inefficient" smallbore magnums such as the .264 Win., 7mm Rem., and .300 Weatherby are all low expansion-ratio rifles, with ERs around 5 or 6. The smaller cartridges with more modest velocity potentials--.22 Hornet, .256 Win. Magnum, .222 Rem., etc.--rate much higher on the ER scale: from 12 to 15. They are more efficient in the sense that they extract more useful velocity and energy from each grain of powder, but they cannot deliver the sheer power of the low-ER cartridge."

Perhaps this should be a separate thread given the apparent misunderstanding.

We now return to our regular programming and consider the .222 Rem. family of cartridges....

 

[357Mag]

South pended-

Howdy, again!

IMHO- An easier case might be made for "ideal case capacity",
For calibre's under consideration.

Ackley talked about " ideal case capacity " and " ideal bore capacity " in his 2 vol treatise..... if I remember correctly.

As regards " expansion ratio " , again:

" The Powley Papers " were a reprint of some of Homer's tech articles, which appeared in the " Guns & Ammo 1974 Annual.
In his ED-9 " Typical Expansion Ratio" chart, he listed the following expansion ratios:
.218 Bee 24" barrel 14.2
.219 Zipper " 7.6
.219 Donaldson " 7.6
.220 Swift 24" barrel 5.6, w/ a 28" barrel expansion ratio - 6.5

Please note: the chart mentioned did not specifically list values for a
.221 Fireball, so I included some smaller capacity .224" cal cases to at least give some idea; by way of comparison.

A review of Ken Waters " case capacity tables " or also the same listed as a drop down tab on on-line version of the "Powley Computer " can show how close the smaller cases listed might be to .221 Fireball in capacity.


With regards,
357Mag

 

[South Pender]

South pended-

Howdy, again!

IMHO- An easier case might be made for "ideal case capacity",
For calibre's under consideration.

Ackley talked about " ideal case capacity " and " ideal bore capacity " in his 2 vol treatise..... if I remember correctly.

As regards " expansion ratio " , again:

" The Powley Papers " were a reprint of some of Homer's tech articles, which appeared in the " Guns & Ammo 1974 Annual.
In his ED-9 " Typical Expansion Ratio" chart, he listed the following expansion ratios:
.218 Bee 24" barrel 14.2
.219 Zipper " 7.6
.219 Donaldson " 7.6
.220 Swift 24" barrel 5.6, w/ a 28" barrel expansion ratio - 6.5

Please note: the chart mentioned did not specifically list values for a
.221 Fireball, so I included some smaller capacity .224" cal cases to at least give some idea; by way of comparison.

A review of Ken Waters " case capacity tables " or also the same listed as a drop down tab on on-line version of the "Powley Computer " can show how close the smaller cases listed might be to .221 Fireball in capacity.


With regards,
357Mag

That's very helpful, 357Mag. I went back into the online Powley Computer and worked out expansion ratios for several .224 cartridges, with some new case-capacity data, and with 24" barrels in all cases and 50-gr. bullets. This is how it shook out holding these factors constant:

.221 FB: 12.7
.222 Rem.: 10.2
.223 Rem.: 8.9
.222 Rem. Mag.: 8.8
.22 PPC: 8.3

So obviously, expansion ratio is not the whole story here (or even the main factor), as the .22 PPC seems to be regarded as probably the most inherently accurate of these five cartridges.

I've also gone back for another read of P.O. Ackley on bore capacity. He discusses other cartridge-case variables like case shape as well as expansion ratio, and how this can effect how efficiently the powder is burned in the case. There are just so many factors at work here that it may be futile to attempt to isolate a most inherently-accurate cartridge from case dimensions alone.

 

[BoydAllen]

A little additional data: My friend had Butch Fisher (accomplished benchrest shooter, gunsmith and inventor of Butch's Bore Shine, who sadly is no longer with us) convert one of Butch's state of the art BAT actioned benchrest rifles to .20 PPC, using an 11" twist Lilja barrel. My friend is a meticulous reloader and keeps exemplary records. He has quite a few targets in that rifle's binder that show five shots under .2 inch. Since he does not shoot competition, and so does not have to worry about rifle weight limits, he switched the scope to a 12-42 NF BR. My point is that taking expansion ratio numbers too seriously can lead you astray.