.264 cal Swift Scirocco II (130 grains) crazy big BC

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High Plains

High Plains

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I’ve used Swift’s Scirocco II 130 grain bullets (130 grains) as my go-to hunting round since I bought a 6.5 Creedmoor in 2014. I picked the Scirocco over the 120 grain Barnes TTSX due to the high BC of the Scirocco. They’re tough bullets so there shouldn’t be a difference in penetration or how fast the animal is dead. What I can’t figure out is why other hunting bullet manufacturers besides Berger don’t have a 130 grain bullet with a high BC. The Scirocco is at .571. The Berger VLD is at .564.
Any ideas???
 
Heavier bullets are longer. Longer bullets have higher BC's. You can only do so much with 130 gr bullets. The 6.5 CM was designed around 140-150 gr bullets with much higher BC's.

Hornady's 143 has a BC of .625, their 147 is .697 and the 153 gr bullet is .704. Their 130 gr bullets are similar with BC's in the mid .500's.

Hunting bullets usually have more rounded profiles and even in the same, or similar weights have much lower BC's. For example the Hornady 130 gr match bullet is .554. Their 129 gr interlock hunting bullet is .445
 
High Plains said:
What I can’t figure out is why other hunting bullet manufacturers besides Berger don’t have a 130 grain bullet with a high BC. The Scirocco is at .571. The Berger VLD is at .564.
Any ideas???
Click to expand...

That's easy. The advertised BC is incorrect. This is what Brian Litz said:

"I measured a G1 BC of .491 for that bullet. G7 BC is .251.

It's got a decent ogive design, but a poor (short and steep) boat tail for base drag reduction. Certainly not a design that could possibly produce a .571 average G1 BC. Even at 3000 fps, the G1 BC is just .515, degrading to .453 at 1500 fps.

A thick jacket for a long bullet...? Sure it makes the bullet longer, but that doesn't mean high BC. Lengthening the nose and tail will reduce drag, but lengthening the bearing surface does nothing for drag so it's irrelevant.

None of my analysis included group shooting (precision) testing so I can't comment on that. They may be extremely precise, but the BC claim is not accurate.

-Bryan"
 
Hummm. Litz is chief among external ballistics experts.
Now I’m wondering what Swift’s techoguys did wrong. I know the deer I took at 378, 388 and 410 yards were with the ballistic program generated data that came from using .571 as the BC.
 
High Plains said:
Hummm. Litz is chief among external ballistics experts.
Now I’m wondering what Swift’s techoguys did wrong. I know the deer I took at 378, 388 and 410 yards were with the ballistic program generated data that came from using .571 as the BC.
Click to expand...

Swift probably estimated. A lot of advertised BCs are wrong. And it doesn't always make a noticeable difference. At 400 yards the difference between inputting .491 and .571, is only 1.2 inches of drop and 1.8 inches drift in a 10mph crosswind. How many people would/could notice?
 
High Plains said:
Hummm. Litz is chief among external ballistics experts.
Now I’m wondering what Swift’s techoguys did wrong. I know the deer I took at 378, 388 and 410 yards were with the ballistic program generated data that came from using .571 as the BC.
Click to expand...

Goosey said:
Swift probably estimated. A lot of advertised BCs are wrong. And it doesn't always make a noticeable difference. At 400 yards the difference between inputting .491 and .571, is only 1.2 inches of drop and 1.8 inches drift in a 10mph crosswind. How many people would/could notice?
Click to expand...

400 isn’t really far enough to realize the penalty. As outlined, it’s less than 1/2moa difference in POI for nearly a tenth difference in G1 BC. Velocity largely still dictates the trajectory at such short range, so the BC influence is inconsequential.

But shooting 400yards isn’t why high BC bullets are made.
 
I picked the Scirocco as my hunting bullet for my 6.5 Creedmoor based on the terminal effect of the bullet and the fact I almost always hunt where wind is a factor. I was thinking the pairing of a high BC and nearly 3000 fps muzzle velocity was a great combo. I’m not changing bullets even though I have great handloads for the the 129gn and 140gn Hornady SSTs.
 
Varminterror said:
400 isn’t really far enough to realize the penalty. As outlined, it’s less than 1/2moa difference in POI for nearly a tenth difference in G1 BC. Velocity largely still dictates the trajectory at such short range, so the BC influence is inconsequential.

But shooting 400yards isn’t why high BC bullets are made.
Click to expand...

Yes, but I don't think many people are shooting 130gr Sciroccos well enough at long enough ranges to notice/identify BC discrepancies. And if they do notice them, I doubt almost anyone will identify the exact reason. And from what I've seen most people who bother "truing" their BCs just seem to adjust the number until the calculation matches their dope. Unless it is a bullet that was recently designed for long range shooting from a select few manufacturers, they probably won't bother to properly measure the BC.
 
Nosler is the worst at stating bc as true! They start out stating 1 bc, then come out with something newer within the same or close too weight and caliber. They 1st advertised the 142ablr @ .719 then came out with the 150ablr (.634) that the 142 dropped .094 in bc (.625 now). With the rdf line giving the 140 a .658 and who knows if it's even close! Hornady and Sierra might be the more honest when listing bc. Just like minimum twist rates and across other gun forums using bullets in barrels that have a slower twist state they have had no stability issues. What would be nice too know is altitude, bmap, temp and velocity when tested or a range of before listing or suggesting twist or bc.
 
I bought some 130's for my 264wm, but haven't tested nor loaded any. Bought them mainly for the use of imr4831. I have 3 264wm's (pre '64, post '64 and 1 for a 110 action build).
 
small town life said:
I haven't checked the g7. Maybe nosler is more forthcoming?
Click to expand...
I know litz did some testing with them a while back and found alot of the ablrs were WAY low when shot in standard twist barrels, and I believe Nosler revamped their BCs some time ago.....but I havent really looked at the reports on the others tho.
 
LoonWulf said:
I know litz did some testing with them a while back and found alot of the ablrs were WAY low when shot in standard twist barrels, and I believe Nosler revamped their BCs some time ago.....but I havent really looked at the reports on the others tho.
Click to expand...
Standard as in minimum or just what most barrels are manufactured with according to which cartridge it's chambered in?
 
small town life said:
Standard as in minimum or just what most barrels are manufactured with according to which cartridge it's chambered in?
Click to expand...
Average twist on production rifles if i remember correctly....so faster twist cals like the 6.5s tended to do better.....

The one i remember specifically was the 168 .284 being noticeably lower in a 9 or 9.25
 
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