DocDoc
Well-Known Member
It was a serious question and there may be some anecdotal evidence from the Berger 7 mm 195 was starting to tumble on impact when the stability was low.
Hunting with a possible marginal stability bullet
- Thread starter Creedmoor shooter
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Mikecr
Well-Known Member
The ultimate wound channel and energy transfer occurs when a bullet tumbles inside game. If his bullets reach game at 300yds, they are stable enough, potentially accurate enough, and possess enough energy to kill.
https://www.thetrace.org/2017/06/physics-deadly-bullets-assault-rifles/
https://www.thetrace.org/2017/06/physics-deadly-bullets-assault-rifles/
blackburbot
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Stability is in flight only. Tumbling after impact is a different factor completely, that's how the bullet expands. At 300 yards you are worrying and stressing about nothing. If the bullet is tumbling at that distance you have more major issues compared to a 1.3 vs 1.5 stability factor. Use quality bullets designed for the caliber and intended target. All critters that I shot didn't care that the bullets I used were last year's issue with a different sticker on the box compared to the ones marketed this year. Spend some time doing quality research and you will be fine
Creedmoor shooter
Well-Known Member
I decided to stay with the 180 eld-m. I really dont want to work up a new load so close to the season. I'm sure I'll be ok. I'll report how the 180 eld-m foes after I get one.
I don't think you will even notice a difference. I shoot the load that works from 80+ to - 35 hunting. The game never noticed a difference either!. It's not paper anymore and hopefully you aren't using three shots on each animal to know you are still shooting .5 moa... I don't like that much hamburger!
7mmTikkaShooter
Well-Known Member
I've shot a 7mm 175 Nosler Accubond LR through a 9.5 twist, which is marginally stable via the Berger calculator, for several years without issue. I've taken deer and antelope out to 400 in temps from single digits to mid 80's with no issues, and steel out past a mile. I feel like you'll be safe to use the 180's.
Mikecr
Well-Known Member
A bullet released as marginally stable only needs to make it past ~10yds without tumbling, for it to reach fully stable beyond.
This, because forward velocity slows way more than radial velocity, so displacement per turn is ever decreasing. Gyroscopic stability goes upward downrange.
The issues with marginal stability are potential increasing of drag early on release (lowering relative BC), and varying aerodynamic jump (hurting accuracy), and risking instability if air density were to increase (less margin).
This, because forward velocity slows way more than radial velocity, so displacement per turn is ever decreasing. Gyroscopic stability goes upward downrange.
The issues with marginal stability are potential increasing of drag early on release (lowering relative BC), and varying aerodynamic jump (hurting accuracy), and risking instability if air density were to increase (less margin).
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I've run bullets that in the sub zero weather had a stability factor of 1.21 - 1.23 without any trouble. Technology sometimes gets us worried about things we previously didn't understand.
Creedmoor shooter
Well-Known Member
Well the 180 eld worked just fine. I took this NH buck this evening at 75 yards. Bullet entered the shoulder busting it, going through one lobe of the left lung and also clipping the top of the heart and exiting out the opposite leg. He's nothing like some of the stuff others get to shoot but for NH he's pretty decent.
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codyadams
Well-Known Member
Very nice!!
codyadams
Well-Known Member
There is evidence to show that a low s.g. can lead to a bullet tumbling, especially in bullets like Bergers that have a small hollow point that is more prone to being closed off on impact if it is somewhat unstable.
However in the o.p.'s case, where he is using a tipped bullet at relatively close range, I wouldn't be too concerned. And it obviously worked. If he was going to be possibly taking a 600+ yard shot, I would start to be more concerned.
Rhett Crider
Well-Known Member
Creedmoor shooter
Well-Known Member
I'll try to give a more in depth terminal performance when I actually get to butcher the deer. The exit was about the size of a quarter. I did not find any fragments in the chest cavity other than bone from the shoulder. The part of the lungs it did hit it liquified. I made a less than perfect shot hitting him alittle forward than what I'd really like but it still did the job.
