16" .308 speed

[J52983 0]

Hi all , I'm trying to find out if anyone has chronographed their 16" barrel .308 , with surplus , or commercial .308 , or whatever . I'm curious to see if theres really that much loss of speed in a 16" barrel.

If anyone has an answer please post , or refer me to a previous post . Thanks for the great forum!

[macbeau 902]

I don't have my data handy, but I ran some handloads, South African, 80's PAK, 70's Indian and some Portuguese across the Chrono about two weeks ago. Rounds out of my 16" S-308 go about 100 fps slower than published velocities on just about any given load. Off the top of my head, I recall that the South African averaged about 2550 fps. That same load runs about 2640 fps in my 21" FAL.

[J52983 0]

Hey thanks for the info , I read some posts on another site ,that made it sound like a .308 out of a 16" barrel was so slow it was hardly worth having . Glad to see that was wrong

[macbeau 902]

In my experience on going with shorter barrels (regardless of caliber), shortning a barrel from - say 24", down to 16", you lose around 20 FPS per inch (+/- 15%)- depending on the bore construction and ammo quality. (IE: How "tight" the bore is, chrome plating?, twist..., etc). Once you go below 16", all kinds of wierd things happen, but mostly - you drop from 50 to 65 FPS per inch under 16". A 12", S-308 barrel would probably yield something in the neighborhood of 2300 FPS (with SA surplus ammo) - which is marginally better that 7.62x39 out of a 16" barrel, given the bullet weight of each).

Others may argue this point, but that is my experience. (Don't get me wrong - I think SBR's are way cool, but in a fighting rifle or competition rifle, If I am gonna use .308, I wannna see the benefit of .308)

The 16" S-308 barrel is very heavy (Large diameter) for it's length and stabilizes bullets in the NATO spec weight range very well (at a 1-12.5" twist, according to the SAIGA / Izhmesh site). Most Mil-Spec FAL barrels (1-12") are fairly thin for their length, un-chromed and become victims of heat more quickly...

(Oddly enough - My 13", Ithaca M37, SBS - shooting Remington 7/8 oz HV slugs (@ 1800 fps according to the box info) Chronos them at 1643 fps - average. My buddies 19" Saiga-12 registers 1655 fps with the same ammo from the same lot. That's about an 12 FPS loss for a loss of 6" of barrel. That's only about a loss of 2 FPS per inch of barrel length. I can't explain why and I wondered if my DATA lied, but there it is... just fyi)

Again - just my experience....

[rwsackett 0]

Cool. Good to know. I've got a 21.8" barrel S-308 and am waiting on a 16" to arrive.

[shaneman153a 39]

In my experience on going with shorter barrels (regardless of caliber), shortning a barrel from - say 24", down to 16", you lose around 20 FPS per inch (+/- 15%)- depending on the bore construction and ammo quality. (IE: How "tight" the bore is, chrome plating?, twist..., etc). Once you go below 16", all kinds of wierd things happen, but mostly - you drop from 50 to 65 FPS per inch under 16". A 12", S-308 barrel would probably yield something in the neighborhood of 2300 FPS (with SA surplus ammo) - which is marginally better that 7.62x39 out of a 16" barrel, given the bullet weight of each).

Others may argue this point, but that is my experience. (Don't get me wrong - I think SBR's are way cool, but in a fighting rifle or competition rifle, If I am gonna use .308, I wannna see the benefit of .308)

The 16" S-308 barrel is very heavy (Large diameter) for it's length and stabilizes bullets in the NATO spec weight range very well (at a 1-12.5" twist, according to the SAIGA / Izhmesh site). Most Mil-Spec FAL barrels (1-12") are fairly thin for their length, un-chromed and become victims of heat more quickly...

(Oddly enough - My 13", Ithaca M37, SBS - shooting Remington 7/8 oz HV slugs (@ 1800 fps according to the box info) Chronos them at 1643 fps - average. My buddies 19" Saiga-12 registers 1655 fps with the same ammo from the same lot. That's about an 12 FPS loss for a loss of 6" of barrel. That's only about a loss of 2 FPS per inch of barrel length. I can't explain why and I wondered if my DATA lied, but there it is... just fyi)

Again - just my experience....

 

How fast is a 7.62x39 on average?

[macbeau 902]

Published velocities (supposedly out of a 16" barrel) run 2250-2450 fps. My experience out of an AK is around 2200 - 2250-ish fps, regardless of ammo maker or rifle, when using mil-surp or Wolf ammo.

(Note* - 7.62x39 Wolf 154 grain SP ammo clocked an average of 2062 fps (with an SD of 13) out of my AIA, M-10, 20" bolt gun and was very consistent. low was 2043 fps, high was 2081 fps - out of 20 rounds tested... Much better than any mil-surp or 123 grain Wolf I have tested...)

Edited January 26, 2007 by macbeau

[O.S.O.K. 0]

Yeah, they always quote velocities for a 20 inch tube - SKS I guess...

[shaneman153a 39]

Published velocities (supposedly out of a 16" barrel) run 2250-2450 fps. My experience out of an AK is around 2200 - 2250-ish fps, regardless of ammo maker or rifle, when using mil-surp or Wolf ammo.

(Note* - 7.62x39 Wolf 154 grain SP ammo clocked an average of 2062 fps (with an SD of 13) out of my AIA, M-10, 20" bolt gun and was very consistent. low was 2043 fps, high was 2081 fps - out of 20 rounds tested... Much better than any mil-surp or 123 grain Wolf I have tested...)

 

Dang, that's the ammo I really wanted to know about, since it's about the same weight. I've been sold on chopping my barrel, and I'm still gonna use it for hunting. I think it will still have the stopping power that I'm looking for, thanks for the data. I didn't think anyone would have it!

[ironhead7544 35]

I just saw a report on the Cor-Bon 150 gr x39 load in a 16 incher. Went 2200 fps. The bullet thats used should expand ok out to 100 yards or so on a deer.

[O.S.O.K. 0]

I just saw a report on the Cor-Bon 150 gr x39 load in a 16 incher. Went 2200 fps. The bullet thats used should expand ok out to 100 yards or so on a deer.

 

I'd think you'd be fine out to 150 with that load. A 30-30 with a 150 grain is good to 175 at least.

[cpileri 0]

http://www.tacticalforums.com/cgi-bin/tact...t=000956#000000

 

(from SGN, platform was a FAL with a 16.25" barrel)

By projectile weight:

 

Hornady TAP 110gr 2894fps

Santa barbara surplus 146gr 2611

Horn. Spire point 150gr 2635

Black Hills Boattail 150gr 2643

Horn. TAP 155gr 2567

Rem. Nosler Ballistic tip 165gr 2573

Sellier&Bellot Match 168gr 2419

Black Hills Match 175gr 2378

 

 

Hope this helps,

C-

Edited January 31, 2007 by cpileri

[caned45 4]

I don't have my data handy, but I ran some handloads, South African, 80's PAK, 70's Indian and some Portuguese across the Chrono about two weeks ago. Rounds out of my 16" S-308 go about 100 fps slower than published velocities on just about any given load. Off the top of my head, I recall that the South African averaged about 2550 fps. That same load runs about 2640 fps in my 21" FAL.

 

 

What was your elevation above sea level. I am sure this would effect the muzzle velocity. The higher up the faster the bullet would go(thinner air the higher you go) Also the Saiga has a new barrel of coarse it may be slower you just have to wear it down a little(round after round).

[macbeau 902]

I don't have my data handy, but I ran some handloads, South African, 80's PAK, 70's Indian and some Portuguese across the Chrono about two weeks ago. Rounds out of my 16" S-308 go about 100 fps slower than published velocities on just about any given load. Off the top of my head, I recall that the South African averaged about 2550 fps. That same load runs about 2640 fps in my 21" FAL.

 

 

What was your elevation above sea level. I am sure this would effect the muzzle velocity. The higher up the faster the bullet would go(thinner air the higher you go) Also the Saiga has a new barrel of coarse it may be slower you just have to wear it down a little(round after round).

Well - I am at about 10 - 12 feet ASL (Coastal GA), but that won't effect muzzle velocity in any noticable way. (BTW - Chronograph for all tested ammo was done at a measured 10' in front muzzles.)

Altitude affects bullet performance (flight path) over distance and pretty much any differences would be un-noticable under 15,000' where the range is 100 yds or less. As you go higher, the air density is less (equating to less resistance / friction on bullets) and trajectories generally flatten out as you go higher. However, under 300 yards, you won't see a huge difference in POA / POI from MSL to about 15,000. That's wat the Army taught me anyway...

Edited January 31, 2007 by macbeau