Will I be over stabilized?

[gunsandgunsmithing]

I believe this is what you are refering to.View attachment 1541709

Yep, that's it. Thank you! Can you elaborate on what it does a little?

 

[gunsandgunsmithing]

AGREE with,.. this ^^^
I've had Grouping problems with NOT getting, "Repeatable" Accuracy from, Hornady 87 V-Maxes, in a 1-7.5 twist barrel, in my 6 xc @ 3,200 - 3,300 FPS +-
But, they Shoot FINE, in my grandsons .243 win. Tikka, 10 Twist @ 3,150+ FPS
I finally gave Up on THIS Bullet ( After MANY, Tries ! ) and gave them ALL, to my grandson for,.. Steel Practice.
He uses, the super accurate, 87 gr. Berger, H-VLD'S, "DRT, Killer Bullets" to Hunt, Deer / Antelope with.
I'm stuck using, the extremely accurate, 95 gr. Classic Hunters for, LR Varmints but, they AREN'T as, "Explosive" !
The 80 gr F B Berger, Var / Targ bullets, also work Great, to 300+ Yds on Sage Rats ( Both Bullets, Cut them in 1/2 ).
But, . NO,.. "Splody" !!!

Lots of potential reasons why your gun performed better with a different bullet, but just for clarity, I'm not talking about anything huge here. I don't think you'll reliably see what I'm referring to in anything less than a really good bench rifle. In fact, I don't disagree with his statement either. I'm just splitting that hair way finer is all, to see where a break point may be. I'd be surprised if a 8 twist will keep up. I feel like I'm close to that break point with this 10 but I'd just have to chamber up say, a 9 and try it.

 

[Alex Wheeler]

I intentionaly build varmint rifles like this. 6 BRA zero freebore with a 55 in an 8 twist really comes apart when they hit. .2 with little tuning.

 

[Murray Brook]

Yep, that's it. Thank you! Can you elaborate on what it does a little?

I really don't know just saw it in another thread about 2 weeks ago. I believe in that thread one of the things it can do is indicate any very small voids in the lead inside the jacket. I'm sure others here know what it's about.

 

[RGRobinett]

I believe this is what you are refering to.View attachment 1541709

Yet another, "back-in-the-day" trekk: when Dave Tooley and [the late] Charles Ellertson talked me into making thirty Cal. FB bullets (187 Gr.) for use during IBS 1K competition, the bullets proved exceptionally good - they were well suited to 1:12" to 1:13:" twist rates (@ Std conditions, the latter delivering Sg 1.4+).

Some of the users were using the Jeunke (Sp?) device to attempt sorting various brands & bullet types - mostly, "VLD" (secant ogive/long BT) type bullets. Most, who sorted via this device, considered anything over 5 deviations useful for fire-forming/practice only . . . I cannot recall all of the deviation details. A good percentage of the BT bullets were deemed unworthy of tournament use.

The 187 Gr. BIB bullets (J4 1.300" long - always 0.0003" or less wall variation) always sorted into < 4 deviations - so, naturally, the fours were sighters and fire-formers . . . yep humans are a weird breed. People using those FB bullets did remarkably well - especially when one compared OPPORTUNITY . . . Perhaps Dave Tooley will chime in and provide some of the stuff I have forgotten.

During that time, on several occasions, to different individuals, I sent sample packs, with jacket wall thickness varying from exceptionally good (<0.0001" wall thickness variation) to horrifically poor - up to 0.0015" variation.

Only yours truly knew which of the coded bullets were made with which ("quality") jackets: not a single Jeunke user came anywhere near to [correctly] sorting based upon variation/amount of jacket wall-thickness. I do not know what the device measures, but firmly believe it is NOT wall-thickness uniformity. What is THE standard for calibration - what IS a deviation? Everyone I was involved with used a few bullets - what if THOSE were, "bad"?? Dark science . . .

Several individuals were so irritated by my test and belief, base upon their Jeunke results, that they quit talking to me and buying bullets! Yes, the packaging was, "tricky" each baggie contained a single bullet, and there were varying combinations of wall variation, with duplicates . . . again, not a single individual came close - nor, did their results correlate.

For cup & core bullets (relative specific gravity, lead:copper), we can determine that center-of-gravity off-set is about 30% of the wall-thickness variation (rounded up to 1/3rd). Thus, if the bullet maker is properly QCing the jackets (knows the correct DATUM points and tolerances), and is either using J4, or, Sierra Match King (specified maximum wall variation 0.0003" at first DATUM above the inside base), the MAXIMUM center-of-gravity off-set would be about 0.0001" . . . certainly not much.

I sure hope Dave will come to my rescue! RG

 

[gunsandgunsmithing]

Yet another, "back-in-the-day" trekk: when Dave Tooley and [the late] Charles Ellertson talked me into making thirty Cal. FB bullets (187 Gr.) for use during IBS 1K competition, the bullets proved exceptionally good - they were well suited to 1:12" to 1:13:" twist rates (@ Std conditions, the latter delivering Sg 1.4+).

Some of the users were using the Jeunke (Sp?) device to attempt sorting various brands & bullet types - mostly, "VLD" (secant ogive/long BT) type bullets. Most, who sorted via this device, considered anything over 5 deviations useful for fire-forming/practice only . . . I cannot recall all of the deviation details. A good percentage of the BT bullets were deemed unworthy of tournament use.

The 187 Gr. BIB bullets (J4 1.300" long - always 0.0003" or less wall variation) always sorted into < 4 deviations - so, naturally, the fours were sighters and fire-formers . . . yep humans are a weird breed. People using those FB bullets did remarkably well - especially when one compared OPPORTUNITY . . . Perhaps Dave Tooley will chime in and provide some of the stuff I have forgotten.

During that time, on several occasions, to different individuals, I sent sample packs, with jacket wall thickness varying from exceptionally good (<0.0001" wall thickness variation) to horrifically poor - up to 0.0015" variation.

Only yours truly knew which of the coded bullets were made with which ("quality") jackets: not a single Jeunke user came anywhere near to [correctly] sorting based upon variation/amount of jacket wall-thickness. I do not know what the device measures, but firmly believe it is NOT wall-thickness uniformity. What is THE standard for calibration - what IS a deviation? Everyone I was involved with used a few bullets - what if THOSE were, "bad"?? Dark science . . .

Several individuals were so irritated by my test and belief, base upon their Jeunke results, that they quit talking to me and buying bullets! Yes, the packaging was, "tricky" each baggie contained a single bullet, and there were varying combinations of wall variation, with duplicates . . . again, not a single individual came close - nor, did their results correlate.

For cup & core bullets (relative specific gravity, lead:copper), we can determine that center-of-gravity off-set is about 30% of the wall-thickness variation (rounded up to 1/3rd). Thus, if the bullet maker is properly QCing the jackets (knows the correct DATUM points and tolerances), and is either using J4, or, Sierra Match King (specified maximum wall variation 0.0003" at first DATUM above the inside base), the MAXIMUM center-of-gravity off-set would be about 0.0001" . . . certainly not much.

I sure hope Dave will come to my rescue! RG

Me too but I don't think you need rescueing. That's a lot more than I KNEW, much less could recall from what I had read alone, as I never owned one. Thank you for your input Randy!

 

[wildcatter]

1-8 twist,,, 55 grain bullet,,,,,, you might get good results in a BR case, I wouldn't expect the same in a 6mm AI!

Anything lightwieght works when your running them slow enough in a fast twist.

 

[ImBIllT]

I’m not sure there is an “over stabilized”, HOWEVER, that doesn’t mean there aren’t possible problems with too much twist.

High rpm exacerbates non-concentric jackets. Today’s bullet jackets are better than those of 20+ years ago, however, they aren’t perfect. Walt Berger identified the level of concentricity that he could not identify changes in group size, and whatever it was, J-4 wasn’t QUITE there, but they were close enough that he stopped making jackets on a lathe. The point is, even J-4’s aren’t quite perfect, and Walt was testing in very slow twist barrels. Short range benchrest level accuracy may not be possible with excessive rpms.

High rpms also cause jacket failures that can result in a bullet not even reaching the target. I’ve had 75 Sierra Varminters, and 87gr Berger VLD’s fail to reach a 100yd target in one piece from an 8” twist 6mm Remington with a 30” barrel. Shorter barrels help. Less twist helps. Lower velocity helps. Some bullets handle excess rpm better than others.

You may not experience any problems at all. If you do, a switch to Ballistic Tips, or Sierra Varminters might solve your problem. A switch to something in the 68-75gr range might solve your problem.