machoking
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I only ever shoot paper to 200 or 300 yards as I'm sure most do. Instability might not rear it's ugly head until further down range in my estimation.
Berger 195's failing?
- Thread starter WeiserBucks
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I only ever shoot paper to 200 or 300 yards as I'm sure most do. Instability might not rear it's ugly head until further down range in my estimation.
Wedgy
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It may have enough stability to fly straight but remember, that bullet WANTS to tip over as the tip is lighter than its base. It would prefer to fly base first. When it does hit flesh it needs stability to keep going straight and expand. Many failures are because the bullet tips over when it hits and results in a unexpanded, bent bullet that changes trajectory.
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longshot406
Active Member
I'm shooting a 28" 8.5 twist krieger with a calculated SG over 1.6 I wouldn't think a tumbling bullet would pin hole?
machoking
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It might not be quite tumbling but oscillating. Think of a football that's thrown in a spiral but not a tight spiral, so the tip is not on the center axis of the spin.
tom m.
Well-Known Member
My buddy accidentally got a bit forward on this cow elk. He shoots them out of a straight 9 twist at a bit under 3000 fps.
It seems to me every lot acts different, or so is my observation.
Tom
It seems to me every lot acts different, or so is my observation.
Tom
A lot of these failure's were under 400 yards. Also 5000 ft in elevation!! Cant see a stability issue at that range . Shot them on paper at 1200 and they grouped very well and made perfect little round holes. Shot a lot of elk with the same guns at further distance with 180 vlds and Nosler Accubonds and they all fell over dead !! The pic that Tom posted is one that did tip over but the bullet did complete opposite as the others (exploded) and they the same lot of bullets that penciled in longshots gun!!
Lonnie
Lonnie
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This is a great thread and disappointing at the same time to hear some of the issues with the 195. I have a SG from 1.67 - 2.5 depending on altitude out of my 28 with a 1/8 twist tube. This appears to be relatively stable according to berger's chart and i guess i never was concerned about it until now.
Can a bullet be considered stable with the above SG's and still be oscilating? I assumed this was the case when a bullet is marginally stable but not when numbers exceeded 1.6. Im not a ballistician so i'm just trying to understand the physics.
I built this gun for elk only and retired my 340 weatherby. Now im wondering if its worth the risk to use the 195's. My plan was to shoot high shoulder, maybe thats a mistake.
Not afraid of trying new bullets in my rig but load is developed/proofed and the clock is ticking on my barrel demise.
Do i switch bullets and start over?
Can a bullet be considered stable with the above SG's and still be oscilating? I assumed this was the case when a bullet is marginally stable but not when numbers exceeded 1.6. Im not a ballistician so i'm just trying to understand the physics.
I built this gun for elk only and retired my 340 weatherby. Now im wondering if its worth the risk to use the 195's. My plan was to shoot high shoulder, maybe thats a mistake.
Not afraid of trying new bullets in my rig but load is developed/proofed and the clock is ticking on my barrel demise.
Do i switch bullets and start over?
Wedgy
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You are good with an 8 twist, 1.5 SG is a minimum and you are well above that.
Manufacturers take a risk when they make heavy for caliber bullets such as the 195 because they often can't be shot from a factory barrel and if they do can get a bad reputation, as perhaps the 195 rumors that won't go away. Berger lists an 8 twist barrel for this bullet which puts if in the custom rifle only niche(I'm not aware of any factory 7mm rifles that come with an 8 twist), thereby shrinking its market. I am in a non-lead state so my 6mm's are 7 twist, 7mm's are 8 twist, and 30 cal are an 8 twist as well. There is a much, much smaller market for these heavy non-lead bullets. Steve at Hammer Bullets(non-lead) is the only one I know of who has tested bullets performance on game in regards to SG, more spin showed better CONSISTANT performance. Think of a top spinning on a desk perfectly concentric and stable, then as it slows down it starts to wobble. Your bullet could be right on the edge of wobbling but when it hits the animal it goes unstable and goes off axis and doesn't perform. I know of no other explanation having seen a cow shot broadside behind the shoulder, the bullet entered then made a near 90 degree turn and ended up in the neck. It was a heavy for caliber .308......certainly lots to think about.
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RockyMtnMT
Official LRH Sponsor
I think stability for hunting should be calculated at sea level regardless of the altitude they will be used at. My opinion from testing says it has more to do with rpm, not balistic stability. The less rpms the quicker it destabilizes on impact. Not saying this is the solution to everthing said here but should be considered.
Steve
Steve
tom m.
Well-Known Member
Rpm defiantly add some extra violence. You guys do realize though, if hitting "point on" was the requirement, they would all fail most of the time. Even stable bullets don't hit with the meplat dead square in the middle of the tear.(mostly)
Tom
Tom
longshot406
Active Member
Hey Steve, how are you testing your bullets, media? I would like to figure out a way to test after trimming meplats or chamfering tips for example to see if it helps expansion.
Later, Leo
RockyMtnMT
Official LRH Sponsor
The easiest home made test that we have come up with is a 1 gallon milk jug in front of news paper to act at a stop. For us we want to see that the bullet did all of its deformation in the single milk jug. Low vel testing we use reduced loads with TrailBoss powder. Full case of trail boss with most cartridges is pretty close to 1800fps. Problem with the reduced load is having enough stability to keep the bullet nose on. Run the bullet, twist rate, and vel in a stability calc to see if you have 1.5sg or not. Low vel testing is how we figured out that when a bullet is marginally stable it will struggle to deform correctly. When we were putting together our initial line of bullets to go to market we were testing every bullet to ensure that they would function properly below 1800fps. We were using a 10" twist .243 to test our 80g Hammer Hunter. We caught the bullet right at 1800fps and the bullet showed zero deformation. Could have loaded it again. So we decided that we would just find the lowest vel that it would work and publish that as a min for that bullet. We could not get enough TrailBoss in the case to get the vel higher but we had a 6-284 Lap imp on hand that we were building for a customer, so we loaded it up hoping for about a 2000fps impact. Took the shot and again had exatly 1800fps. Thought that was a waste and dug the bullet out to find a perfectly deformed bullet. Difference was the twist. The 6-284 had a 7" twist. Stability with it was over 1.5sg where the stability with the 10" twist was right at 1.2sg. I instantly had flash backs through years of hunting and seeing bullet performance that was "goofy" that I had blamed on bullet construction. Before this test I was always pushing the envelope on stability. Marginal stability was not an issue in my mind if I was getting round holes and shooting sub moa at 1000y.
Tom is correct. Bullets do not hit exactly point on. The less point on the bullet impacts the harder it is to get fluids down into the hollow point. Every bullet needs fluid to get into the bullet and cause it to deform from the inside out. Bullets that have lead all the way out to the nose have an advantage because the lead will act like the fluid. If you look at the hollow point of xxx dia. As you angle the bullet the available size of the hole to accept fluid gets smaller. The smaller the hollow point the more susceptible it is to yaw on impact causing bullet failure. This is why we will not use a hp smaller than 1.5mm in a hunting bullet. They are not as effective and we will not sacrifice terminal performance in order to increase the bc. Rotational vel has very little degradation in flight. It instantly slows down on impact helping to encourage the bullet to wobble thus reducing the available size of the hollow point to accept the needed hydraulics to expand the bullet from the inside out. Think of the bullet as a top spinning. The faster it spins the truer it remains and the more force it takes to knock it off axis. Bullets are no different.
This holds true for a tipped bullet as well. Tipped bullets will have large hollow points but the hole is plugged, requiring the tip to get out of the way so that the hydraulics can enter the hollow point. So unless the tip is of a more robust material than the bullet it will not cause the bullet deform more easily. Once the tip is broken off and allows the fluids into the large remaining hollow point, it will work very well. So tipped bullets have all the same issues plus a plugged hollow point.
So when guys take the time to trim the meplat of a bullet and increase the size of the hp it increases the probability of proper terminal performance even if it is on the marginal side of stability.
Remember that stability calculators give you data for external ballistics (will this bullet fly properly). They do not tell you if your stability is good for terminal ballistics.
I had said earlier that stability for terminal performance should be calculated at sea level even if you are hunting at higher elevation. The higher elevation helps stability for flight characteristics. We have used elevation in our calculations for hunting bullets and seen terminal performance not as good as we expect. The amount of rotational vel needed to overcome the atmospheric conditions and fly well is different than the amount of rotational vel needed to overcome impact and perform terminally.
Through our testing in media and on game, our conclusion is hunting bullets should be considered properly stable for terminal performance, with a minimum of 1.5sg at standard atmosphere at sea level. I can't say that it would solve every problem that is stated in this thread, but I think it would considerably reduce the risk of bullet failure. It does us no good as a bullet manufacture to help people to get bullets from another manufacture to work better, but it's the right thing to do.
Hope I did not hijack
Steve
Watching this thread. Just picked up a 7 mm Dakota with a 26" 8 twist Benchmark. Guy threw in 225 Berger 195's. Hope they work for me. He's got them shooting good but only at 2700 fps with 7828. I'm going to try them with N570 and R33.
