When looking at ballistics tables there are far better rounds out there, like my .270 for example. More velocity, less drop, less wind drift, etc. But the 308 is almost always the caliber people use. Why is that? Does it have something to do with inherent accuracy coming from rate of twist in a barrel that particularly likes that round?
Why is 308 so popular for Precision?
- Thread starter SigSavage
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Topic has been beaten to death many times already. One of the more recent threads:
http://www.canadiangunnutz.com/foru...-Discussion-Why-308-and-not-NEW?highlight=308
http://www.canadiangunnutz.com/foru...-Discussion-Why-308-and-not-NEW?highlight=308
But no standard rifle barrel has a twist fast enough to use 'em. Obviously custom barrels is an option, but a lack of faster-twist rifles causes a trickle-down effect through the rest of the industry.
The issue with the 270 and 257cals is the lack of faster twist rates from factory rifles, when compared to 7mm or 6.5mm respectively. Because of this, the bullet selection in the heavier weights is less than some others. Sure, you can get 170 and 180 grain 270 bullets, but there are not nearly as many options as a heavy 6.5mm or 7mm bullet.
As for the 308 issue, there are disciplines that are restricted to 308 rifles.
One reason might be that there is a match category F Class target rifle (F-TR) that limits shooters to either 308 or 223 so a lot of people choose the 308. There are lots of bullet choices for 308 and barrel life is great so that might account for why you see this. Also, in competitions where the ranges are known (400, 600 yards etc) flat trajectory is less important than things like BC, form factor drag, etc.
So the preference is to go with heavier bullets? This is counterintuitive to me, as you will get more velocity and less drop in the lighter bullet. Is it because heavier bullets are more stable out of a given barrel with a given rate of twist, and therefore more accurate?
All things considered equal, would not a 204 Ruger out of a barrel optimized for a 40 grain bullet not outperform a 308 bullet from its optimized barrel just based on speed, drift and drop? Can that 204 bullet not be stablized and therefore be as accurate as a 308?
I'm speaking strictly from wanting to hit a gong out at 600-1000 yards, not because of interest in competitions (i.e don't care about class restrictions etc)
I read that thread linked above and it doesn't really say anything about one round being inherently more accurate than another.
Basically, this is a conversation I was having with a buddy of mine. We are both wanting to get a Varmint type gun for shooting out a bit further. I really would like a Tikka HB Varmint, Tactical or Sporter if one came up for a good price. Then we got talking about what caliber we would want to go with. He was saying that he was reading something about the 223 being particularly accurate due to the rate of twist of the barrel they usually come in, acting with the ballistic coefficient to make that round particularly accurate, even if the ballistics charts don't look all that great compared to the 204 I was thinking of. Then I started wondering if it was even worth getting a separate rifle for long distance paper punching when I already have a pretty good 270 (Savage FCSS). Now reading all this stuff makes me wonder about the 308 again because I see a lot of them on the EE. I would not be competing, or putting hundreds of rounds a year down the barrel so cost of shooting is not really a huge deciding factor for me. At this point it's more a question of "do I really need another gun for this, and if so, what caliber would I want?"
All things considered equal, would not a 204 Ruger out of a barrel optimized for a 40 grain bullet not outperform a 308 bullet from its optimized barrel just based on speed, drift and drop? Can that 204 bullet not be stablized and therefore be as accurate as a 308?
I'm speaking strictly from wanting to hit a gong out at 600-1000 yards, not because of interest in competitions (i.e don't care about class restrictions etc)
I read that thread linked above and it doesn't really say anything about one round being inherently more accurate than another.
Basically, this is a conversation I was having with a buddy of mine. We are both wanting to get a Varmint type gun for shooting out a bit further. I really would like a Tikka HB Varmint, Tactical or Sporter if one came up for a good price. Then we got talking about what caliber we would want to go with. He was saying that he was reading something about the 223 being particularly accurate due to the rate of twist of the barrel they usually come in, acting with the ballistic coefficient to make that round particularly accurate, even if the ballistics charts don't look all that great compared to the 204 I was thinking of. Then I started wondering if it was even worth getting a separate rifle for long distance paper punching when I already have a pretty good 270 (Savage FCSS). Now reading all this stuff makes me wonder about the 308 again because I see a lot of them on the EE. I would not be competing, or putting hundreds of rounds a year down the barrel so cost of shooting is not really a huge deciding factor for me. At this point it's more a question of "do I really need another gun for this, and if so, what caliber would I want?"
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I get that at longer distances the 204 will start to drop more due to more rapid loss of energy, like a .22 but in my mind right now I'm thinking out to 500-600 yards and wanting to choose an inherently more accurate round (if that's even possible). I see what you mean though, where a 308 may be a better all rounder if just bullet drop was the main deciding factor.
Muzzle velocity is a depreciating asset, ballistic coefficient is forever. Sure the lighter bullets start out faster, but at long range the heavier bullets maintain their velocity longer. This and the higher BC mean they drift less in the wind.
What can you throw further, a tennis ball or a tennis ball-sized rock?
What can you throw further, a tennis ball or a tennis ball-sized rock?
Yeah, I get that (as stated above). Good analogy heh heh. But is there an innate ability to stabilize heavier bullets and thus make them more accurate when shot from a barrel with an optimized rate of twist for that particular caliber, as in 308 vs 204?
Stability is one of the factors affecting the BC of a bullet. BC is highest when stability is 1.5, and drops off by 3% when dropping stability by 0.1
Doesn't mean barely stabilized bullets (eg SG of 1.1) can't be very accurate, just they are running with a depressed BC.
As for inherent accuracy, a little bit. Fast twists will exacerbate issues with poorly balanced bullets, which will affect your precision. One of the reasons short range benchrest shooters use medium weight bullets and twists. Use quality match bullets and you won't really have to worry about it.
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The answer is simple. BC. The 300gr .338 Sierra MK have a BC of 0.77. That's not possible in a smaller diameter caliber.
I am not a fan of .308 but understand it's popularity. Mic McPhee builds one barrel. 30 cal. It's a proven winner in many disaplines and is easy to reload and tune. This is true of .223. FTR is a really good example of this.
I am not a fan of .308 but understand it's popularity. Mic McPhee builds one barrel. 30 cal. It's a proven winner in many disaplines and is easy to reload and tune. This is true of .223. FTR is a really good example of this.
