24 inch vs 20 inch


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DML2007
February 13, 2008, 08:21 PM
High Road,

What am I gaining or lossing in barrel length in a 30-06 or a .308 with either a 20 or 24 inch barrel?

Im looking to hit paper up to 800 meters. Basically just have fun and challenge myself.

Id like to keep it rather cheap (600 or less rifle only) and I like the Remington 700 SPS with a 24in tapered compared to the Remington Tactical 20 inch bull.

What does a heavy/bull barrel do compared to a tappered?

Thank you, Dave

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nathan
February 13, 2008, 09:07 PM
Bull is less vibration and barrel whip. I would pick it vs the 24 inch. ANyway powder burns in the first 18 inch of travel.

MCgunner
February 13, 2008, 09:18 PM
ANyway powder burns in the first 18 inch of travel.

True for shotguns, not really for high powered rifles.

Depends on the case as to how barrel length affects it. The .308 shoots a fast powder from a small case capacity. The .30-06 powders aren't really THAT much slower, but a little. Conventional wisdom is that belted magnums work best with 26" barrels and lose more as the barrel is trimmed, but most factory rifles including my Savage in 7 mag come with 24" barrels. I'd go with a 24 on a .30-06, but here again, most long action cartridges come with a 22", which really is fine. My .308 in my Remington M7 works quite well with a 20" barrel and it's a very short gun, very handy and light hunting rifle. I get 2800 fps out of a 150 grain bullet, so I'm happy, wouldn't want any more barrel on that gun, not and give up some handiness and light weight. That's why I bought the gun. The old M7s had 18" barrels, but I reckon 20 is a little better for ballistics in the caliber, good compromise between the handiness of the rifle and performance of the bullet IMHO.

R.W.Dale
February 13, 2008, 09:48 PM
If you'll take things to extremes and compare reloading data for a 14" handgun vs a 24" rifle in 308 and 30-06 you'll find that there is no real reason to carry a rifle with a bbl longer than 18"

According to hodgon shooting a 150grn bullet with a max load of varget

308win

14" handgun 2675 FPS vs 2937 for a 24" rifle for a loss of 262FPS for 10" of barrel or 26fps per inch

30-06

2582 FPS for the handgun vs 2975 for the rifle, for a loss of 393 FPS for 10" difference or 39 FPS per inch

raz-0
February 13, 2008, 11:35 PM
If you'll take things to extremes and compare reloading data for a 14" handgun vs a 24" rifle in 308 and 30-06 you'll find that there is no real reason to carry a rifle with a bbl longer than 18"

According to hodgon shooting a 150grn bullet with a max load of varget

308win

14" handgun 2675 FPS vs 2937 for a 24" rifle for a loss of 262FPS for 10" of barrel or 26fps per inch

30-06

2582 FPS for the handgun vs 2975 for the rifle, for a loss of 393 FPS for 10" difference or 39 FPS per inch

For the .308, at 800 yards like the OP stated, you are talking an extra 40 inches or so of bullet drop.

For the 30-06 you are talking nearly 60 inches of extra drop.

down range that 250-400fps matters. It's also not going to be completley linear inch per inch. Not to mention with handloads, you can go with slower burning powder to maxmise the benefit of a longer barrel .

Barrel length vs. twist also plays a part in how heavey a bullet you can use, which also makes a difference down range.

From my reading, an 18" barrel in .308 is less than ideal. A good 20" barrel can perform quite nicely, 22" is generally regarded as the sweet spot, and more than 24" starts to have diminishing returns in general even with handloading.

a 20" barrel makes for a very handy bolt action.

Art Eatman
February 15, 2008, 12:24 PM
For the '06, figure roughly losing 75 ft/sec/inch when going from 24" to 20", or 300 ft/sec.

For the .308, roughly 40 ft/sec/inch, or 160 ft/sec.

Given how important muzzle velocity is when looking at Ma Bell distances, I'd definitely go with a 24" barrel.

jimbob86
February 15, 2008, 12:48 PM
ANyway powder burns in the first 18 inch of travel.

Not necessarily so. That depends entirely on the burn rate of the powder. Pistol powders need to develop their pressures much faster than rifle powders. Rifle powders don't need to have as steep of a pressure curve.

Here is my experience: In loading for two different .270 WIN rifles, one with a 22" barrel, and one with a 24", I found that the shorter barrel generated 100 to 150 f/sec less with a slower powder (IMR 7828) than the longer barreled rifle with the same load. The difference was greatest with heavy for caliber (150gr) bullets. With a quicker powder (IMR 4064) and light (100gr) bullets, there was less difference in MV.

I have also read in one of my manuals somewhere that you should not expect to reach to reach the advertised muzzle velocities of factory loads (generally measured with a 24" test barrel in standard chamberings) with a shorter barrel.

mighty2
February 15, 2008, 02:06 PM
I would recommend the Savage 10FP, very good weapon for the money.

R.W.Dale
February 15, 2008, 02:12 PM
For the .308, at 800 yards like the OP stated, you are talking an extra 40 inches or so of bullet drop.

For the 30-06 you are talking nearly 60 inches of extra drop.

TRUE but those numbers are for a 14" handgun vs a 24" rifle. As I stated two extremes. the difference from a 24 to a 20" tube is almost meaningless at all but the longest ranges. Especially given that there are no garentees . As an above poster alludes to a short but "fast" barrel can sometimes outperform a longer barrel.

In my opinion with only 4" difference the "speed" of the particular barrel will play more of a role than the length diffrence.


Another MYTH being repeated is the powder burnrate vs Barrel length theory.

Just look at reload data for rifle caliber handguns VS rifles in the same chambering, 9 times out of 10 the fastest powder for a 24' rifle is still the fastest powder in the 14" or 15" handgun as well. The fact is that ALL of the rilfe powder that is going to burn will do so in the first 5 or 6 inches of bullet travel.

Zak Smith
February 15, 2008, 03:21 PM
Amount of powder "burned" in X inches is mostly irrelevant. If you really want to know about it, buy a copy of QuickLoad and see how various loads fare. What you'll find is that for the vast majority of loads, 98-100% of the powder is burned at any legal barrel length. However, this does not mean that additional barrel inches do not increase muzzle velocity. That "burn" served to create a lot more volume of gas, and as long as that gas is expanding with sufficient pressure, it'll accelerate the bullet.

-z

skinewmexico
February 15, 2008, 03:48 PM
I know that if I'm shooting at 800m, I want all the help in barrel length I can get.

rangerruck
February 15, 2008, 10:32 PM
i concur, I like minimum 24 inch bbl, with either of those cals. the other dude is
very right as well, another 200fps at the muzzle, shows up in vert. inches way out there.

General Geoff
February 15, 2008, 11:11 PM
If you want to maximize dividends with your caliber, then go with the 24".

conrad carter
February 23, 2008, 12:57 AM
American Handgunner had a good article about barrel length in the Mar/Apr issue. I think JD Jones wrote it. He compared short barrels to the longer ones.

ALS
February 23, 2008, 10:42 AM
Ideally a 26 inch barrel would be the best for the 3006 or .308.
But since you are specifying a 20" or 24" barrel go with the 24"

MachIVshooter
February 25, 2008, 01:47 AM
For bench work, there's no good reason not to go long. When talking about hunting rifles, you want the best compromise between weight/length (portability) and performance. What that generally means is ~22" for SA cartridges, ~24" for LA cartridges and ~26" for the bigger magnums. And believe me when I tell you that a 26" tube can be a whole lot more cumbersome than a 24 incher-it is amazing how many more branches, etc. are snagged by that extra 2".

But for a range gun, that extra length simply does not matter and will only serve to increase velocity, which means that your bullet stays super sonic longer and has less flight time, which translates into better accuracy (all else being equal). More barrel means more velocity, period (unless you start talking incredibly ridiculous lengths at which the friction actually does exceed the gas pressure and begin to slow the bullet, but that's a really long barrel WRT centerfire rifle cartridges.

One of my upcoming projects is a 300 RUM with a 30" tube.

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