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January 20, 2023
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Pete settles the argument with a controlled experiment: bullets can be understabilized but not overstabillized.
See there?
- Bill
WACA # 65205; life member, NRA; member, TGCA; member, TSRA; amateur preservationist
"I have seen wicked men and fools, a great many of both, and I believe they both get paid in the end, but the fools first." -- David Balfour, narrator and protagonist of the novel, Kidnapped, by Robert Louis Stevenson.
April 15, 2005
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Zebulon said
Pete settles the argument with a controlled experiment: bullets can be understabilized but not overstabillized.
See there?
I partially disagree… they can be pushed too fast while being overspun. I recently ran into that issue with some 110 grain bullet loads in 30-06. As I approached the max load of 58 grains of IMR 4064, the accuracy very grossly fell off (16″ group @100 yards).
Bert
WACA Historian & Board of Director Member #6571L
January 20, 2023
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Very interesting. I assume your barrel was cut 1:10? Gas checked? Jacketed?
- Bill
WACA # 65205; life member, NRA; member, TGCA; member, TSRA; amateur preservationist
"I have seen wicked men and fools, a great many of both, and I believe they both get paid in the end, but the fools first." -- David Balfour, narrator and protagonist of the novel, Kidnapped, by Robert Louis Stevenson.
April 15, 2005
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Zebulon said
Very interesting. I assume your barrel was cut 1:10? Gas checked? Jacketed?
Yes… I was shooting my 1927 production Model 54. The bullets are Polymer tipped copper jacketed.
Bert
WACA Historian & Board of Director Member #6571L
May 23, 2009
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Wouldn’t this also be no different than having to hot of a load?
You send the bullet so fast that you start to melt it in flight and the bullet starts to smoke in flight. Once you start melting it, doesn’t it literally become unstable? As you are literally disintegrating the bullet? Also known as a bullet “blow-up” or “vaporization”.
Sincerely,
Maverick
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April 15, 2005
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Maverick said
Wouldn’t this also be no different than having to hot of a load?
You send the bullet so fast that you start to melt it in flight and the bullet starts to smoke in flight. Once you start melting it, doesn’t it literally become unstable? As you are literally disintegrating the bullet? Also known as a bullet “blow-up” or “vaporization”.
Sincerely,
Maverick
Possibly, but I do not believe my loads were going fast enough to blow-up the bullets. I did not chronograph them as I was merely ladder testing for accuracy. I had no signs of excess pressure, just poor accuracy. The same bullet with 55.5 grains was shooting 1.5″ @100 yards. I will need to see what the chronograph has to say on my next trip to the range.
Bert
WACA Historian & Board of Director Member #6571L
November 7, 2015
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Bert H. said
Maverick said
Wouldn’t this also be no different than having to hot of a load?
You send the bullet so fast that you start to melt it in flight and the bullet starts to smoke in flight. Once you start melting it, doesn’t it literally become unstable? As you are literally disintegrating the bullet? Also known as a bullet “blow-up” or “vaporization”.
Sincerely,
Maverick
Possibly, but I do not believe my loads were going fast enough to blow-up the bullets. I did not chronograph them as I was merely ladder testing for accuracy. I had no signs of excess pressure, just poor accuracy. The same bullet with 55.5 grains was shooting 1.5″ @100 yards. I will need to see what the chronograph has to say on my next trip to the range.
Bert
I suppose it’s possible to spin it fast enough to distort the jacket even if the bullet doesn’t fly apart or vaporize like smaller caliber bullets sometimes do. I suspect a 110gr 30 caliber bullet would have a rather thin jacket as it was intended for varmints rather than big game. OTOH maybe you were just pushing that bullet faster than it wanted to go!
Mike
January 20, 2023
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One theory is the decrease in accuracy observed from “overstabilization” is caused by a rotational velocity high enough to heat the bullet core, to the extent any flaws and voids in the core distort the bullet shape, which makes its flight path unpredictable.
This could occur with an unjacketed lead bullet as well but not, presumably, with one made of solid copper or bronze.
Unfortunately, measuring rotational velocity directly is beyond our means, although i guess there are mathematical formulae that compute rotational velocity as a function of bullet velocity, given that and other known constants like twist, barrel length, and bullet dimensions.
It would be useful to record the bullet velocities and the velocity at which the phenomenon occurs, with that bullet. Ideally, a monolithic bullet of the same weight and shape would be shot to the same velocity, to see if inaccuracy occurs. Whether it did or did not, we would learn something.
- Bill
WACA # 65205; life member, NRA; member, TGCA; member, TSRA; amateur preservationist
"I have seen wicked men and fools, a great many of both, and I believe they both get paid in the end, but the fools first." -- David Balfour, narrator and protagonist of the novel, Kidnapped, by Robert Louis Stevenson.
November 7, 2015
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I haven’t had the pleasure of reading Pete’s article yet but I have read that a lead bullet will strip or fail to engage the rifling at extreme rotation speeds. I suppose there is a point where a jacketed bullet could fail to engage the rifling although it would be somewhat higher. Best way to determine if the bullet is stripping is to recover a bullet and examine the rifling marks.
I think I’ll see if my copy has made it to my PO box!
Mike
March 31, 2009
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TXGunNut said
I suppose it’s possible to spin it fast enough to distort the jacket even if the bullet doesn’t fly apart or vaporize like smaller caliber bullets sometimes do. I suspect a 110gr 30 caliber bullet would have a rather thin jacket as it was intended for varmints rather than big game. OTOH maybe you were just pushing that bullet faster than it wanted to go!
Mike
Some jacketed bullets if over spun, too much speed, can have the jacket separate from the core.
April 15, 2005
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I just purchased a batch of Hornady V-Max 110 grain .308 bullets… I will give them a try to see if that solves the problem.
Bert
WACA Historian & Board of Director Member #6571L
January 20, 2023
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Bert H. said
I just purchased a batch of Hornady V-Max 110 grain .308 bullets… I will give them a try to see if that solves the problem.
Bert
Good move. Could you chronograph them as you go up the ladder?
- Bill
WACA # 65205; life member, NRA; member, TGCA; member, TSRA; amateur preservationist
"I have seen wicked men and fools, a great many of both, and I believe they both get paid in the end, but the fools first." -- David Balfour, narrator and protagonist of the novel, Kidnapped, by Robert Louis Stevenson.
April 15, 2005
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Zebulon said
Bert H. said
I just purchased a batch of Hornady V-Max 110 grain .308 bullets… I will give them a try to see if that solves the problem.
Bert
Good move. Could you chronograph them as you go up the ladder?
That is my intent… I am looking for an accurate load somewhere in the 3,400 – 3,500 fps range.
WACA Historian & Board of Director Member #6571L
January 20, 2023
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TXGunNut said
I haven’t had the pleasure of reading Pete’s article yet but I have read that a lead bullet will strip or fail to engage the rifling at extreme rotation speeds. I suppose there is a point where a jacketed bullet could fail to engage the rifling although it would be somewhat higher. Best way to determine if the bullet is stripping is to recover a bullet and examine the rifling marks.
I think I’ll see if my copy has made it to my PO box!
Mike
Absolute velocity may make a difference as well. Pete was comparing 25/20 rounds shot from a typical barrel and from a 25/35 barrel with a much faster twist.
- Bill
WACA # 65205; life member, NRA; member, TGCA; member, TSRA; amateur preservationist
"I have seen wicked men and fools, a great many of both, and I believe they both get paid in the end, but the fools first." -- David Balfour, narrator and protagonist of the novel, Kidnapped, by Robert Louis Stevenson.
January 20, 2023
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Bert, you mentioned the 110 grain .308 bullets were polymer tipped and copper jacketed — the ones that suddenly produced 16″ 100 yard group. That was before you got to 58 grains of 4064.
For the record, what was the powder charge weight that produced the phenomenon and what was the group size and charge weight just before it on the ladder?
And the brand of the bullet?
We know the rifle was your 1927 M54.
Bill
- Bill
WACA # 65205; life member, NRA; member, TGCA; member, TSRA; amateur preservationist
"I have seen wicked men and fools, a great many of both, and I believe they both get paid in the end, but the fools first." -- David Balfour, narrator and protagonist of the novel, Kidnapped, by Robert Louis Stevenson.
April 15, 2005
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Zebulon said
Bert, you mentioned the 110 grain .308 bullets were polymer tipped and copper jacketed — the ones that suddenly produced 16″ 100 yard group. That was before you got to 58 grains of 4064.
For the record, what was the powder charge weight that produced the phenomenon and what was the group size and charge weight just before it on the ladder?
And the brand of the bullet?
We know the rifle was your 1927 M54.
Bill
Bill,
All loads were IMR 4064, 5-shot groups
55.0 grains = 2″ group
55.5 grains = 1.5″ group
56.0 grains = 2.25″
56.5 grains = 3+” group
57.0 grains = 6+” group
58.0 grains = 16″ group
The barrel was heating up and may have contributed to the problem.
My next trip to the range will be with the following loads;
| 110 gr PT | IMR 3031 | 52.0 | REM 9 ½ | 3.2″ |
| 110 gr PT | IMR 3031 | 52.2 | REM 9 ½ | 3.2″ |
| 110 gr PT | IMR 3031 | 52.4 | REM 9 ½ | 3.2″ |
| 110 gr PT | IMR 3031 | 52.6 | REM 9 ½ | 3.2″ |
| 110 gr PT | IMR 3031 | 52.8 | REM 9 ½ | 3.2″ |
| 110 gr PT | IMR 3031 | 53.0 | REM 9 ½ | 3.2″ |
I am going with a faster burning powder with the light bullets.
Bert
WACA Historian & Board of Director Member #6571L
January 20, 2023
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Got it. Thanks. I don’t have much experience with the 110 grain bullet but, from one session years ago with my M70 Featherweight that was capable of 1.25″ to 1.5″ 100 yard 3 shot groups, the 110 bullet (a Speer HotCor) would stay within 1.5″, satisfactory for Coyotes that became suspicious and hung back. The Fwt is a hunting rifle and those groups were adequate for the task. I didn’t own a chronograph.
- Bill
WACA # 65205; life member, NRA; member, TGCA; member, TSRA; amateur preservationist
"I have seen wicked men and fools, a great many of both, and I believe they both get paid in the end, but the fools first." -- David Balfour, narrator and protagonist of the novel, Kidnapped, by Robert Louis Stevenson.
April 15, 2005
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Zebulon said
Got it. Thanks. I don’t have much experience with the 110 grain bullet but, from one session years ago with my M70 Featherweight that was capable of 1.25″ to 1.5″ 100 yard 3 shot groups, the 110 bullet (a Speer HotCor) would stay within 1.5″, satisfactory for Coyotes that became suspicious and hung back. The Fwt is a hunting rifle and those groups were adequate for the task. I didn’t own a chronograph.
My goal is to develop a 1 MOA load, but if I can get it under 1.5″, I will be content.
WACA Historian & Board of Director Member #6571L
January 20, 2023
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While ammunition and components have improved enormously since our rifles were made, there are some limitations inherent in the latter that preclude our meeting current accuracy standards of the industry.
If we wanted microscopic groups badly enough, we’d give up the fine rifles once made in New Haven and buy space guns ugly enough to make a saint spew. I’d rather take up Blackpowder or Siluetas and shoot a weapon with some soul and history.
Mind you, I don’t look down on the precision shooting sports and will cheer on my friends who are enthusiasts. But the romance and history of hunting fuels my collecting and shooting interest, as I’m pretty sure it does yours.
If I’m able to get out into the field again, it will be with a .33 WCF, a .38-55, or a .303 Savage. Why? Because I can, finally, after all these years.
- Bill
WACA # 65205; life member, NRA; member, TGCA; member, TSRA; amateur preservationist
"I have seen wicked men and fools, a great many of both, and I believe they both get paid in the end, but the fools first." -- David Balfour, narrator and protagonist of the novel, Kidnapped, by Robert Louis Stevenson.
December 9, 2002
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Zebulon said
While ammunition and components have improved enormously since our rifles were made, there are some limitations inherent in the latter that preclude our meeting current accuracy standards of the industry.
If we wanted microscopic groups badly enough, we’d give up the fine rifles once made in New Haven and buy space guns ugly enough to make a saint spew. I’d rather take up Blackpowder or Siluetas and shoot a weapon with some soul and history.
Mind you, I don’t look down on the precision shooting sports and will cheer on my friends who are enthusiasts. But the romance and history of hunting fuels my collecting and shooting interest, as I’m pretty sure it does yours.
If I’m able to get out into the field again, it will be with a .33 WCF, a .38-55, or a .303 Savage. Why? Because I can, finally, after all these years.
I’m in agreement with you Bill!
Do what you’re able to get out and do! Hearing about you shooting that Shiloh puts a smile on my face, as I had to pass on a Buffalo Hunt, using an ole’ original traditional Single Shot Rifle that’s just itchin to put some Buff. meat in the freezer! Darn schedule!
Tony
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