@ 01:10 pm (GMT)
Scott StruifNot to open a can of worms, but . . .
Barnes original X bullet came out in 1989.
In 1997 Barnes coated the bullet with a lubricant, and marketed it as the XLC.
Also in 1997, Winchester-Nosler introduced their combined technology coated Ballistic Tip. My guess is they didnt want to be one-upped by Barnes. Even though there was no need to coat the Ballistic Tip, the lubricant yielded a small MV benefit, and perhaps reduced copper-fouling slightly.
In 2003 Barnes came up with banding. This obviated the need for lubricant. The grooves cut in the shank of the bullet reduced friction, and provided a place for the copper shaved off by the rifling to go.
This technology was copied by the the other bullet manufacturers: Hornadys GMX (now CX); Federals Trophy Bonded Tip, Trophy Bonded Copper, & Terminal Ascent; Noslers E-Tip; Winchesters XP Copper; Cutting Edges Raptor; etc.
This guy isnt a hunter, but he shoots a lot. According to him, banded bullys are less accurate:
@ 02:40 pm (GMT)
Re: Drive band bulletsHeres an example of the bullshit in action:
@ 12:46 am (GMT)
Re: Drive band bulletsBless your heart.
@ 09:45 am (GMT)
Re: Drive band bulletsWe fall for crap too easily. When it appeals to our reason, we ignore the lack of empirical evidence.
Take the 4 branches of ballistics: Internal, Transitional, External, and Terminal.
The Internal and Terminal branches lend themselves to empirical proof. The more powder, the faster the projectile. The more frangible the bullet, the more upset when it strikes the target.
As to the Transitional branch, its all theory. The notion that lead-core bullets obturate to fill the bore sounds good, but hasnt been proven.
The External branch is similarly the realm of speculation. Some people go to the trouble of reverse-calculating BC by measuring drop at distance. These endeavors dont take account of the effect of unique rifling striations. Nor do they fully account for environmental factors.
So, I take with a grain of salt presentations like this:
@ 08:14 am (GMT)
Re: Drive band bulletsHornadys Heat Shield Tip is another example. They tout it as the be-all-end-all of External ballistics:
But they also point out that a 7mm 162 gr SST® has a 500 yard radar-verified average BC of .520. When tested with a Heat Shield® tip, it only gained a small amount of BC - .532. The .012 increase in BC is too small to matter on this bullet at any distance this bullet would expand on game.
Their honesty is admirable. But how many of us read all that crap? Their point is to convince us we dont want our tips melting. If you dig deeper on their website:
In that whitepaper they attempt to sell us their tips with an appeal to our reason:
Put simply it is the air temperature on a point behind a shock wave where the air flow is completely stopped. As the ambient air temperature goes up or down so goes the stagnation temperature. Think of the movies you have seen with the Space Shuttle or Apollo 13 with the vehicle reentering the atmosphere and the heat generated because of this. The only difference in small arms ballistics is we are talking hundreds of degrees instead of thousands of degrees.
@ 04:56 am (GMT)
Re: Drive band bulletsHeres another video dealing with transitional and external ballistics. Some new concepts for me:
The rear end of boat tail bullet is supposedly squeezed together by the combustion gasses, whereas a flat base is forced outward.
A flat base bullet supposedly escapes the turbulence of muzzle blast, whereas a boat tail is engulfed by it and must fight its way free.
It all sounded good enough to some people to come up with a rebated boat tail, a new one on me.
@ 12:02 am (GMT)
Re: Drive band bulletsI cant speak to banded bullets. As to Hornady, the improved tip does seem to be empirically proven - with the Doppler data to back it up. If I remember right, it was divergent Doppler data that led them to discover that their standard tip design wasnt behaving uniformly or in line with computation. Sierra noted they could see no such issues with their own tips, but they were much later to the party as well.
Im most interred in how their new 109 ELD-M compares to their 110 A-tip last I read, the intent was to make the bullet otherwise the same apart from tip. GAP and the 6 GT crowd will have the first crack, of course. Just another data point. [b]
@ 05:22 am (GMT)
Re: Drive band bulletsRegarding competitors non-heat-shield tips, Hornadys whitepaper states, These changes in the drag on the projectile will reduce impact velocities at 800 yards 75 to 125 fps. This loss of velocity/energy is directly correlated to a loss in terminal performance.
Theyre talking about Noslers Long-Range Accubond. To me, as a hunter, its a distinction without a difference. I suppose 100 fps at 800 yards could matter to some people, though.
If youre shooting 6mm competition, I could see where having a new ELD-M to try is worthwhile. It might make a good long deer bullet, too.
@ 04:11 am (GMT)
Re: Drive band bulletsMy take is borrowed from Brian Litz - ultimately, consistency wins. I agree with you that a slightly lower BC isnt significant IF its consistent and I think thats the larger issue. I side with Nathan on the Accubond - its not a good long range bullet, no matter what its BC is. Id take an SST, ELD-X, or ELD-M over it without hesitation. The TMK too, come to that.
@ 07:54 am (GMT)
Re: Drive band bulletsHeres a Hornady A-Tip video:
Another new term for me: Drag Variability.
They define this phenomenon as high and low fliers, where the muzzle velocity is the same. They attribute it, in part, to shrinkage of polymer tip material in the manufacturing process. They bash HPBT match bullets because they contain minor imperfections in their meplats. (In contrast, the Aussie guy says it doesnt matter because the bullet rides on a bubble of air in front of it.) They dont say why its so difficult to manufacture a HPBT with a smooth meplat.
In another video (at 2:00), Hornady claims that bullets wobble when they leave the barrel and wake up:
They dont say how they know this, but claim the aluminum tip allowed them to tweak the center of gravity to get the bullet to stabilize (i.e., go to sleep).
This is similar to Cutting Edges claim on their website:
Boat Tail - Rear tapered portion of a bullet intended for shooting further than 400 yards. It is useless under that yardage and flat base bullets are a better choice as they stabilize, or go to sleep, quicker than boat tailed bullets. At further distances however boat tails have a higher BC and retain their energy much better than flat base bullets. Boat tail bullets do not fully stabilize in less than 300 yards but may still group well. We recommend working up loads at over 250 yards for best long range performance.
No evidence is offered to support any of these theories. Implicit in Hornadys marketing of their A-Tip is a condemnation of their polymer tipped bullets.
@ 12:54 pm (GMT)
Re: Drive band bulletsThis is actually the video (promoting their ELD-M), where Hornady slams HPBT match bullets. (They still make HPBTs, of course.)
They have no promotional videos on their website for their HPBTs. I assume there are competition shooters who still use them.
They state in their ELD-M video that they came up with their Heat-Shield Tip for hunting bullets. Then they decided the benefits were so wonderful they should put them on their match bullets, too.
Nathan has shown that a HPBT match bullet can be transformed into a hunting bullet with a drill bit, a file, a pan of water and a propane torch. But no one would go to the trouble if you could buy something off-the-shelf you dont have to fuck with.
Its amusing, though, watching Hornady cast doubt on their polymer-tipped bullets with a new concept, drag variability.