Bghunter338
Well-Known Member
Send me a pm. We can talk about it more. I don't want to be rude and take away from this tread. I respect Cody and we should leave this thread to the badlands as it was ment.
Badlands Precision Bullets thread - From BC to terminal ballistics
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For monos, it has been established and backed by Applied Ballistics that a stability factor (SG) of 2.0 is best. An SG of 1.5 is good for lead core bullets, yes, but they're more dense and shorter as a result, grain for grain. Due to the mono being longer, it needs more RPMs to keep the center of pressure far enough towards the nose of the bullet and away from the center of gravity.
Anything below 2.0 with a mono is marginal or worse. Anything getting significantly above that, on the other hand, isn't gaining you any significant stability overall, but will increase the effects of centrifugal force as the bullet impacts and begins to expand.
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You meant longer?
I think the primary reason the monos need the higher SGs for more reliable terminal performance is because they maintain much longer shanks after expansion and/or shedding of petals, compared to lead-core bullets.
I've now had three copper monos divert off-course in extreme fashion. All three maintained long solid shanks after shedding their noses.
Those long shanks of copper monos can help ensure deep penetration, but in my experiences, can also corkscrew off-course in unbelievable fashion. How does the shank of a copper mono bullet enter a moose standing broadside - just behind the shoulder - and end up under the hide next to the bung hole?
Until you experience it - see it with your own eyes - you wouldn't believe a bullet could veer off-course 85 degrees yet still penetrate 4 1/2 half foot of moose. This bullet still had enough velocity to shatter the femur in one of the rear legs. It would have exited the rear ham of the moose, if it hadn't been slowed by the large femur!
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Yes. I edited the typos lol
How consistently and evenly, and immediately, those petals open or separate will also determine how they are influenced and manipulated through tissues. If all that occurs unevenly, it can cause the bullet to veer off course as a result to either creating an imbalance, or material that allows the bullet to get pulled off course, usually tumbling.
Higher RPMs definitely helps increases the stability factor, but it also increases centrifugal forces and those equate to higher G forces on material that begins to expand and peel away from the rest of the bullet. It helps more evenly, quickly, and consistently create petals and also separate them if so designed.
Does the extra stability also help the remaining shank or remaining mushroomed mono travel straight? Yes, I'm sure it does, but my point is it's only part of it and the added centrifugal forces help a ton and perhaps more than stability alone.
Both of my recovered bullets that corkscrewed off-track had shed all petals and left with just a shank with a blunted nose.
The third one exited the rear ham of a caribou. Unrecoverable, so I can't know about that corkscrewed copper mono.
I wonder if an SG for the terminal performance of copper mono that shed petals shouldn't be calculated based on the length of the copper mono shank from base of bullet to the bottom of the hollow point in their tips. I suspect there's an SG based on that length of remaining copper shank that would indicate improved likelihood of straight line penetration. And the SG value would no doubt be quite high. Up in the 4.0 zone because of the reduced length of bullet shank. The remaining shank length after petals are shed.
The third one exited the rear ham of a caribou. Unrecoverable, so I can't know about that corkscrewed copper mono.
I wonder if an SG for the terminal performance of copper mono that shed petals shouldn't be calculated based on the length of the copper mono shank from base of bullet to the bottom of the hollow point in their tips. I suspect there's an SG based on that length of remaining copper shank that would indicate improved likelihood of straight line penetration. And the SG value would no doubt be quite high. Up in the 4.0 zone because of the reduced length of bullet shank. The remaining shank length after petals are shed.
You do get shoulder stabilization from the surrounding tissues. It's not the same as flogging through just air. You can't really calculate it the same. And if you did, you need the BC of that shank and remaining velocity to really help you figure its SG.
If you search this thread for "25-06" you should find my results for doing exactly what you are asking. I have rebarreled since then, but I would not personally attempt to do what you are asking. There are other 0.257" mono options that do stabilize with 1:10" twist. Maybe someday Badlands will come out with an 80gr 0.257" for those folks shooting factory 1-10" twist rates or those that just like things that go fast
Right. SG is intended to predict sufficient stabilization of bullets during flight through air, so that bullets can be delivered down range with good precision.
Is Bryan Litz's recommendation of a SG of 2 to ensure the precision of copper mono bullets? I presume he's recommending SG of 2 for improved terminal performance in animals. Because I've had copper monos shoot well with SGs less than 1.5. As low as 1.3
Is Bryan piggybacking the application of SG for copper mono bullet performance in game, because there isn't any better predictive model available?
No, I have had a personal discussion about just that with Bryan. He hasn't done any testing terminally regarding stability yet, although says it stands to reason it plays a part. The 2.0 SG for monos is what he and his crew have found is best for in flight stability. To quote him, "it's what we recommend as a baseline for solids".
I have asked him his thoughts on SG and terminal stability and he was reluctant to give any opinion since it would only be speculation since he's yet to test that stuff thoroughly.
Thanks for your response.
Wow. I'd have never suspected that. Because lots of guys report getting good precision way down range, with SGs substantially less than 2.0
Yeah, in our conversation, that was discussed. It's not like below 2.0 will automatically result in tumbling in flight, but it definitely makes it more susceptible, especially at longer distances and if the bullet enters transonic.
You're just taking more of a risk, but the biggest thing you'd be losing is full BC potential of the bullet. It might be stable enough to fly pretty true, but the slight oscillation it'll have will ultimately lower BC.
So I'd be curious how far down range those guys are shooting and what they've done to adjust for hitting their target at the POA. Typically you don't see much need to adjust your inputted BC or MV until 600 yards or more. If they're shooting that far or more, I'd be curious if and how much they are adjusting their BC or MV to get impacts to match up.
I'm led to believe guys winning the 2-mile competition (King of 2 Miles) are commonly shooting copper monos, because the BC values of lathe-turned copper monos are so consistent from bullet to bullet. Which is critical at those extreme ranges.
Cutting Edge Bullets advertises their bullets are being used to win that competition and other extreme range competitions.
Also, I've read David Tubb has used Warner Flat Line copper monos in extreme long range competitions. And has won it in the past.
I have not read about, or had access to, the fine details concerning SG values those competitors strive for with their selected barrel twist tates.
Cutting Edge Bullets advertises their bullets are being used to win that competition and other extreme range competitions.
Also, I've read David Tubb has used Warner Flat Line copper monos in extreme long range competitions. And has won it in the past.
I have not read about, or had access to, the fine details concerning SG values those competitors strive for with their selected barrel twist tates.
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You are correct
