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Old July 13, 2009, 01:36 AM   #1
Telgriff
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Barrel Length for .270

Been going back and forth on the .270 and .308 for my next rifle. From what I have read around the net, it seems the .270 requires a longer barrel for peak performance, somewhere in the vicinity of 22" or longer, where as the 308 seems to prefer a shorter barrel (20" or shorter).

I know that barrel length equates to velocity, so my main concern is whether there are barrel length limitations to the .270

Is this correct?
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Old July 13, 2009, 01:55 AM   #2
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The smaller case capacity of the 308 (and larger bore volume) means that it can burn all its powder in a shorter barrel. BUT the still expanding gasses will give it an effective velocity boost the longer the barrel. For this reason it isn't uncommon to see 24 and 26 inch barrels for 308 rifles. Even longer for some competitive shooters.

If you want a short handy rifle, the 308 makes a good choice. If you want a flatter shooting rifle in a common caliber the 270 is a good choice. For hunting there isn't much advantage of one over the other.

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Old July 13, 2009, 03:58 AM   #3
Telgriff
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Was more for consideration of hunting where a longer barrel may be a hindrance (where I consider 24" or longer as long). Sectional Density the .270 seems to have the edge unless using 165 and heavier projectiles for the 308. So it seems to be a case of one or the other trade off.

Thanks for the input Jimro.
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Old July 13, 2009, 05:43 AM   #4
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I find 22" to be a pretty good compromise with either. If you want a shorter barrel go 308. There is not much difference between 22 and 20". I might be tempted to go as short as 18" if you really want a shorter barrel.
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Old July 13, 2009, 06:10 AM   #5
Telgriff
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20" would be suitable (though I haven't found many rifles chambered in .270 with a 20" barrel). Was more a concern for velocity on either cartridge and whether those few inches will cause any loss of performance.
Doesn't help most ballistic tables are based on 26" barrels.
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Old July 13, 2009, 08:12 AM   #6
flyguyskt
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look at the velocity of a 308....then a 270. no way to honestly compare the 2. the 270 will shoot flatter because it is faster.

you may lose 100 fps per inch you cut off the barrel
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Old July 13, 2009, 09:08 AM   #7
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In like rifles the difference in trajectory between the .270 and .308, both shooting 150gr bullets is less than 15yds figuring MPBR; 287 vs 275yds for the .308. They are not as different as many would believe. If most all your shots are 250 yds or less, it's pretty much a moot point, IMO. The .308 will be slightly shorter and lighter in like rifles, due to it being a S/A vs L/A for the .270. They are both excellent cartridges that I use often and interchangeably for any deer hunting I do. I doubt you, or any deer would be able to see any big difference in performance inside 350 yds.

A link to a chart showing velocity loss in 2" increments:
http://www.loadammo.com/Topics/October05.htm



Here is a quote from an article found on Guns and Shooting Online by Chuck Hawks reference relative velocity loss for several popular calibers.
*************
For standard high intensity cartridges in the same test, the Lyman technicians chronographed the cartridges in barrel lengths ranging in length from 24 inches down to 20 inches with the following results:

The average loss for the .270 Win./130 grain bullet was 37 fps per inch.
The average loss for the .270 Win./150 grain bullet was 32 fps per inch.
The average loss for the .300 Sav./180 grain bullet was 17 fps per inch.
The average loss for the .30-06/180 grain bullet was 15 fps per inch.
The average loss for the .35 Rem./200 grain bullet was 11 fps per inch.

After a bunch of disclaimers, the Lyman people concluded, "The rule of thumb is that high speed, high pressure cartridges shed more speed in short barrels than do the low speed, large bore types." It's funny, but that is what I had suspected all along! ************

Last edited by pilothunter; July 13, 2009 at 02:07 PM.
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Old July 13, 2009, 12:38 PM   #8
Art Eatman
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Dunno if its the use of more modern powders or what, but the numbers from Hawks' tests don't jibe with those given from repeated cut-off experiments written up in "The Dope Bag" of the American Rifleman, back in the 1940-1980 period. These articles showed up every five to ten years or thereabouts. Generally, for such as the .270 and '06 class, it tended to run about 75 ft/sec/inch from the beginning 26" length. Around 40 ft/sec/inch for such as the .308.

Anyhow, the .270 is somewhat overbore and velocity is pretty much best from barrels around 24" to 26". I've always figured that if a person wants a barrel more toward a carbine length, go to a shorter-case cartridge. E.g., a .308 or 7mm08.

FWIW, going back to its earliest days, hunters have always had good results on deer with the 130-grain bullet. Articles about elk hunts usually spoke of using the 150-grain bullets...
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Old July 13, 2009, 12:49 PM   #9
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telgrif,

A 20 inch barreled 308 can be quite accurate at long range, 600 meters plus. Just use heavier pills and know your ballistics. If you are hunting in an area where a long barrel gets snagged on vines and brush then a 20 inch 308 would be a very good choice.

The 308 and 270 are dead even when it comes to killing power, so I wouldn't worry about either. Just find the rifle that fits your body best in the configuration that will be most useful to you when hunting. Good luck.

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Old July 13, 2009, 12:50 PM   #10
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Barrel Length

For me the length of the barrel on the rifle I am carrying is determined by what and where I am hunting. Or what type of cover I am hunting in(heavy vs. sparse).

I think for the heavier areas with shots under 200-250 yards I will go with a shorter-faster handling rifle. And I want it to be in a larger bore. So that means at least 30 caliber-or preferably even larger. It is pretty hard to beat the 358 Winchester or the 338 Federal for a fast handling rifle out to that distance. Remington makes a pump carbine rifle in 30-06, they used to make it in 308-not sure if they still do or not. However this rifle or a fast handling lever is the berries out to the 250 yard mark.

If you are hunting in open country then the longer barrel with the higher performance velocities are the proper choice.

So it really depends on you, and how and where you hunt. And what you already have in the safe. You indicated that this is going to be your "Next" rifle. So I am assuming there are some dandies in the safe already. Tom.
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Old July 13, 2009, 01:55 PM   #11
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22" in the 308 (150gr) will give you 2900+ and 24" in the 270(130) will give you 3100+.
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Old July 13, 2009, 02:54 PM   #12
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your ballistic coefficient on the 270 is greater than the .308

around .496 for a 140 grn 270

around .435 for a 150 grn .308

so the 270 will shoot flatter given that and the 100 plus fps from equal barrels.

couldnt go wrong with either of them with a 20 inch barrel.

maybe a featherweight 270 if heft is a concern.
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Old July 13, 2009, 05:17 PM   #13
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I've never seen anything in print showing anything close to 75 fps/inch loss in velocity. According to a Remington ballistics chart I have.

If your muzzle velocity with a 24" barrel is within the following ranges either add or subtract.

2000-2500 10 fps/inch
2500-3000 20 fps/inch
3000-3500 30 fps/inch
3500-4000 40 fps/inch.

Rifles are individuals as well. It is not unusual to see a 22" barrel from one gun shoot the same ammo faster than a 24" barrel in another gun.
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Old July 13, 2009, 05:21 PM   #14
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Oh come on!

Ballistics charts!? Throw em out!
B.C. You should be looking at .260 Remington or 7mm-08?

There is NO .270 Bullet superior to the best offerings in 6.5/7mm/.308, so just buy the handiest rifle and get over it!
The great Jack O'Connor wrote the .270 Winchester into mythological magic. Fact is the .280 Remington is superior. But in the end the differences are so miniscule it doesn't matter. Please buy a .308 (or a 7mm-08)
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Old July 13, 2009, 05:32 PM   #15
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I have to disagree with the last post. Barnes offers it's Original bullet in 180gr in 270. This bullet has a sectional density that is superior to the 175 7mm, or 200 gr 308. Maybe you threw out the tables too soon, should have read them first maybe.
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Old July 13, 2009, 05:32 PM   #16
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Either round will harvest game handily. The comparative lack of high BC competition bullets in 270 bore hasn't stopped it from being a damn fine round for hunting. On the flip side the "rainbow like" trajectory of the 308 hasn't stopped it from killing animals either.

Get the rifle that fits you best.

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Old July 13, 2009, 06:47 PM   #17
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Get the rifle that fits you best.

Jimro

Handler,

He's right and so are you. your SD reference to a newer bullet still means nothing to the animal hit. The BC is more important in placement of that bullet.
A 260gr 6.5 in the boiler room of an ELK still means the same thing as that "new" 180gr .270

Seeing as how you're out there in Big Sky Country, I'll respectfully defer to your experience though
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Old July 13, 2009, 07:48 PM   #18
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A QUOTE:
I've never seen anything in print showing anything close to 75 fps/inch loss in velocity. According to a Remington ballistics chart I have.

If your muzzle velocity with a 24" barrel is within the following ranges either add or subtract.

2000-2500 10 fps/inch
2500-3000 20 fps/inch
3000-3500 30 fps/inch
3500-4000 40 fps/inch.

Rifles are individuals as well. It is not unusual to see a 22" barrel from one gun shoot the same ammo faster than a 24" barrel in another gun.**END QUOTE

Now, there's someone who has, quite obviously, studied the subject and done RECENT research!
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Old July 13, 2009, 08:30 PM   #19
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Do you prefer a shorter length rifle, but want the benefits of a long barrel? Take a look at the falling block from Ruger (#1B).
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Old July 13, 2009, 08:41 PM   #20
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Stop picking nits! I have both, using them interchangeably. They are both effective.
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Old July 14, 2009, 01:11 AM   #21
Telgriff
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The S/A is the winner

Appreciate all the feedback, opinions and data everyone has provided, its been a big help.
As I mentioned before, the .270 was only a contender because of its high SD, and the .270 chosen over the 6.5 SE due to nearly completely lack of factory ammunition for the Swede here.

Range wise it would be both open field shots (200 yards would be maximum for my confidence) as well as brush shots if I go up into the hills/bush, so mobility in those areas is to be considered also.

The 7mm08 seems very good also, **edit**
Wait what? Similar ballistics to the 308, good long range and less recoil?

Last edited by Telgriff; July 14, 2009 at 01:31 AM.
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Old July 14, 2009, 03:14 AM   #22
Jimro
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The 7mm-08 was developed for silhouette shooting and took the step from wildcat to factory ammunition. It is equivalent to the 7x57 in terms of effectiveness. Don't expect a significant recoil reduction, the laws of physics will not be denied.

That being said it is not a very common caliber like the 308 or 270. The 308 is a good choice because it is a common military round in use by governments the world over. From Australia to India to South Africa as well as all the NATO members. Surplus ammo (or new FMJ) makes great plinking/practice fodder.

I own exactly one "rare" caliber, a 9.3x62 Mauser. There is no way that I can reliably pick up ammo at any store. Even Cabelas leaves me high and dry. However they carry ammunition for all my milsurps (308, 30-06, 8x57, 7.62x54, 5.56x45) and 270. And I have a really good chance of having 308, 270, and 30-06 being available even in remote areas.

If you are worried about recoil, get a thick buttpad, muzzle break, and add weight to the stock. All big game rifles kick, but there is a lot you can do to fix it.

However, if you find a 7mm-08 that you absolutely love and you can live with limited ammo availability (you handload or buy in bulk) then by all means get it. For ranges 200 and under even a 30-30 can do you just fine (deer size or smaller). Remember, having the rifle fit you is the most important part.

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Old July 14, 2009, 06:18 AM   #23
Telgriff
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I agree, a recoil reduction, even if its only minor, is hardly worth it for my needs.
308 is the winner for me, which also opens up a huge range of rifle options instead of a select few...
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Old July 14, 2009, 10:20 AM   #24
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Hoorah!

Telgrif- good for you!

Jimro-you're my new hero!
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Old July 14, 2009, 02:18 PM   #25
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I love .308 because its got great performance in a short action package. Plus, the amount of information out there about the .308 for hunting, target shooting or so called "sniping" is insane. it might not be the flattest shooting bullet ever but with the information you can get about it you will hit your target.
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