txcookie
Member
test
well that didnt work were on the screen is it located?? I feel kinda dumb but I cant find it ?????
well that didnt work were on the screen is it located?? I feel kinda dumb but I cant find it ?????
How do you quote a post btw?????
[/noparse] after it[/noparse] in front of it and [noparse]
screename of person you are quoting said:[/noparse] in front
test
well that didnt work were on the screen is it located?? I feel kinda dumb but I cant find it ?????
Please share where this instability of .277 caliber bullets is documented since we are having a factual discussion here, not relying on snake oil.Trajectory is very similar. The 30-06 has a more stable bullet at a more optimum speed according to Chuckhawks. The 30-06 has a long proven edge in accuracy and killing power. But so many people believe the old Winchester salesman that the .270 is a wonder cartridge that it is hard to get a factual discussion.
The .270 has a slightly flatter trajectory beyond 500 yards which is beyond it's effective range due to bullet instability. Under 300-400 yards there is no big difference in the 150 grain bullet. Either one is effective beyond normal hunting range and in that grain bullet it is a toss-up. Recoil should be the same. I have a
Couple 30-06 rifles, I would not buy a .270 because at my age I might not notice
The small difference in bullets and try to load the wrong ones. When you are absent minded and vision isn't the best, you need caution.
Also as bench rest shooters know, skinny and fast isn't optimum in bullets, the mythical flatter shooting .270 is mostly that. It is somewhat flatter , barely in same weight bullets, but at the cost of stability.
That's easy: Vodka. I'd be throwing up the gin too quickly for it to soak in.This
This thread is akin to asking wich will get you drunk better, vodka or gin.
You realize that SD factors into BC, right?BC= trajectory
SD= penetration
A super fast 220 swift is not for elk and a 45-70 sucks for prairie dogs, lets stop with the numbers game!
Where do you get this stuff? There are no, none, nada, zip stability issues with bullets in the .270. There's no magic to figuring out rate of twist required for a particular bullet length and .277 cal bullets aren't particularly long for their caliber. The standard 1:10 twist of a .270 has mo problems with the Woodleigh 200gn.In response to the question about stability there are formulas such as Miller and Greenhill to calculate this. Basically a long skinny bullet does not stabilize as well as a fat bullet. Other factors such as,bullet shape aside from B.C. Bearing surface, rifling twist etc. the 270 is not used in serious target shooting or bench rest unlike the .308 because no one has solved the optimum shape, twist rate,
And velocity to make the .270 work. Recently Outdoor life did a project on the .270. It's like spinning a pencil like a top. Hard isn't it. The .270 is a great round.
If you prefer it fine. Just trying to shed light on popular myths.
helotaxi said:The .308 isn't a serious target round anymore
yes I do.You realize that SD factors into BC, right?
At normal hunting ranges they are very close to equal. Outdoor life built a 270 special target rifle, there's a online article about it. The results were poor. 1 1/2 groups at 100 yards for a benchrest rifle. At long range shooters a guy has built a good rifle for long range but it takes a lot of knowledge and custom components to make the .270 shoot well. Many guys have trouble finding a load to shoot well in the long range hunting forum.
I could not find the article I read about the .270 awhile back so for anyone interested I will attempt to relate the jist of it.
The op wants to compare 150 grain .270 to .30 cal 150 grain. The factory .270 load shows a .291 BC load for the .270. Much different that the Sierra .500 something bullet. Why?
Dumb maker that doesn't want to sell ammo?
Several reasons. Rifle bullets are heavier toward the rear, center of gravity is behind midpoint of bullet. A long high BC bullet is more so. Plus it has a longer jump to the lands causing greater wobble and deformation. Also it has less bearing area causing it to be less concentric to the bore. Since the bullet is tail heavy it needs more rpm to stabilize but there are points of diminishing returns.
Once out of the barrel. The smaller diameter of the bullet has a less gyroscopic effect than a .30 cal bullet.
The net effect is to match the stability of the .30 cal, the .270 has to spin faster
And has a lower BC bullet. that negates the higher SD of the .270.
Also when the .270 slows it begins to lose stability and wobble.
This all can be overcome with custom bullets, barrels and chambers designed for a specific bullet. But then you are at the starting point of a 30-06.
For 3-400 yard hunting none of this matters but you might want to know about it.
Of course many rifles do outshoot theory and there are factors I don't recall.
This is a bullet problem, not a cartridge, twist or voodoo problem.At normal hunting ranges they are very close to equal. Outdoor life built a 270 special target rifle, there's a online article about it. The results were poor. 1 1/2 groups at 100 yards for a benchrest rifle.
You're making a lot of assumptions here. First you're assuming the factory (not sure which factory you're talking about) bullet, which based on the high SD that a 150gn .277 cal bullet would have is probably a round nose, not a bullet suitable for long range work. A 150gn Interbond or SST has a BC over 0.5, more than 0.1 higher than a like bullet of the same weight in .30cal. Second a 150gn .277 bullet will have a very long bearing surface and the .270 cartridge has a very long neck. Those two things negate the whole "small bearing surface" and bore alignment issue. A 150gn .30cal with a boat tail will have a very short bearing surface so much more likely to suffer from the problem that you describe if the rounds are not well assembled. Lastly, the location of the CG does have some impact on the spin required to stabilize the bullet, but it actually helps the bullet stabilize as it slows down, not the other way around. The problem is not that the CG is aft of the center of the bullet, that is actually irrelelvant. The issue is that the aerodynamic center of pressure is forward of the center of gravity so the two forces acting on the bullet are acting on different points. This means that once the bullet is upset significantly, it will be very unlikely to return to stable, nose forward flight. This is true for any spitzer pointed bullet. The key then is to get the bullet out of the bore cleanly with minimal wobble. The long shank of a heavy .277cal bullet makes this fairly easy. As the bullet slows from drag, the force acting on the aerodynamic CoP decerases, but the gyroscopic moment stays fairly constant. RPM decays much more slowly than velocity. The result is a bullet actually becomes more stable from a gyroscopic standpoint as it goes further downrange. This does require the bullet to come out of the bore cleanly and be well made and balanced. None of these issues are unique to the .270 and the .270 is not especially plagued by them because of "unique" bullet designs.The op wants to compare 150 grain .270 to .30 cal 150 grain. The factory .270 load shows a .291 BC load for the .270. Much different that the Sierra .500 something bullet. Why?
Dumb maker that doesn't want to sell ammo?
Several reasons. Rifle bullets are heavier toward the rear, center of gravity is behind midpoint of bullet. A long high BC bullet is more so. Plus it has a longer jump to the lands causing greater wobble and deformation. Also it has less bearing area causing it to be less concentric to the bore. Since the bullet is tail heavy it needs more rpm to stabilize but there are points of diminishing returns.
Once out of the barrel. The smaller diameter of the bullet has a less gyroscopic effect than a .30 cal bullet.
The net effect is to match the stability of the .30 cal, the .270 has to spin faster
And has a lower BC bullet. that negates the higher SD of the .270. Also when the .270 slows it begins to lose stability and wobble.
None of the "custom" stuff is required and other than the velocity difference with like bullets weights compared to the .30-06, the .270 is not at any particualr disadvantage. Again, I'm not sure where you got your info, but you need to recheck it. If you're the inquisitive type, Applied Ballistics for Long Range Shooting is a must read.This all can be overcome with custom bullets, barrels and chambers designed for a specific bullet. But then you are at the starting point of a 30-06.
For 3-400 yard hunting none of this matters but you might want to know about it.
Of course many rifles do outshoot theory and there are factors I don't recall.