Firearm & Gun Forum - FireArmsTalk.com > Long Guns > General Rifle Discussion > shooting 308 in 7.62x51 rifle

Reply
 
LinkBack Thread Tools Display Modes
Old 10-31-2012, 02:11 PM   #11
Feedback Score: 0 reviews
 
303tom's Avatar
 
Join Date: Sep 2011
Location: Missouri
Posts: 3,342
Liked 1084 Times on 747 Posts
Likes Given: 1103

Default

.223/5.56...........
According to the official Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (C.I.P.) guidelines the .223 Remington case can handle up to 430 megapascals (62,366 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. This is equal to the NATO maximum service pressure guideline for the 5.56x45mm NATO cartridge.

According to the official NATO proofing guidelines the 5.56×45mm NATO case can handle up to 430 MPa (62,000 psi) piezo service pressure. In NATO regulated organizations every rifle cartridge combo has to be proofed at 125% of this maximum pressure to certify for service issue. This is equal to the C.I.P. maximum pressure guideline for the .223 Remington cartridge, that is the 5.56×45mm NATO parent cartridge.

.308.7.62............
Although not identical, the 7.62×51mm NATO and the commercial .308 Winchester cartridges are similar, and even though the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) considers it safe (by not listing it) to fire the NATO round in weapons chambered for the commercial round, there is significant discussion about compatible chamber and muzzle pressures between the two cartridges based on powder loads and wall thicknesses on the military vs. commercial rounds.

According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) guidelines the .308 Winchester case can handle up to 415 MPa (60,190 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers...............

__________________

When all else fails.

303tom is offline  
 
Reply With Quote
Old 10-31-2012, 02:32 PM   #12
JTJ
FTF_SUPPORTER.png
Feedback Score: 0 reviews
 
JTJ's Avatar
 
Join Date: Oct 2010
Location: Lake Havasu,Arizona
Posts: 5,800
Liked 1739 Times on 946 Posts
Likes Given: 547

Default

The problem in the 223 chambered rifles is the throat. It is longer in the 5.56. While it is only a 10% overload which is easily handled by most actions the shorter throat can cause a pressure surge to 30% or higher especially with the heavier bullets. Now as to the 308, I have fired surplus 7.62x51 in a 308 and had heavier recoil and mild signs of high pressure. The NATO round was hotter than the 308. I believe it was South African. I have never had an opportunity to fire 308 in a NATO chambered rifle.

__________________

Patron Member NRA
"I would not be an old man if I had not been an armed young man." JTJ
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and promoted by mainstream media, which holds forth the proposition that it is entirely possible to pick up a piece of feces by the clean end."

JTJ is offline  
 
Reply With Quote
Old 10-31-2012, 02:32 PM   #13
Moderator
FTF_MODERATOR.png
Feedback Score: 0 reviews
 
JonM's Avatar
 
Join Date: Nov 2009
Location: Rochester WI,Rochester WI
Posts: 17,191
Liked 5314 Times on 2774 Posts
Likes Given: 335

Default

Quote:
Originally Posted by 303tom View Post
.223/5.56...........
According to the official Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (C.I.P.) guidelines the .223 Remington case can handle up to 430 megapascals (62,366 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. This is equal to the NATO maximum service pressure guideline for the 5.56x45mm NATO cartridge.

According to the official NATO proofing guidelines the 5.56×45mm NATO case can handle up to 430 MPa (62,000 psi) piezo service pressure. In NATO regulated organizations every rifle cartridge combo has to be proofed at 125% of this maximum pressure to certify for service issue. This is equal to the C.I.P. maximum pressure guideline for the .223 Remington cartridge, that is the 5.56×45mm NATO parent cartridge.

.308.7.62............
Although not identical, the 7.62×51mm NATO and the commercial .308 Winchester cartridges are similar, and even though the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) considers it safe (by not listing it) to fire the NATO round in weapons chambered for the commercial round, there is significant discussion about compatible chamber and muzzle pressures between the two cartridges based on powder loads and wall thicknesses on the military vs. commercial rounds.

According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) guidelines the .308 Winchester case can handle up to 415 MPa (60,190 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers...............
The difference is in throating. 556 and 308win have longer throats than 223 and 762nato have shorter throats. When you load longer profile bullets into those chambers the pressure jumps radically to dangerous levels. The 762nato is chambered to use a 147grain bullet when you use larger ones in the 175grain and up the ogive can touch the lands. Thats why you dont use 308win in a nato chamber.
__________________

"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith

The problem with being stupid is you cannot simply decide to stop doing dumb things...

JonM is offline  
 
Reply With Quote
Old 10-31-2012, 06:55 PM   #14
Feedback Score: 0 reviews
 
Yunus's Avatar
 
Join Date: Jan 2009
Location: |,Maryland
Posts: 4,715
Liked 1038 Times on 613 Posts
Likes Given: 319

Default

If I am not mistaken I believe another difference is the method used to measure pressure is different for the american specs (.223, .308) than for the european specs (5.56, 7.62). This means the numbers are not an apples to apples comparison.

__________________

"Good people drink good beer."
Hunter S. Thompson

Yunus is offline  
 
Reply With Quote
Old 10-31-2012, 07:33 PM   #15
Weapons Aficianado
FTF_SUPPORTER.png
Feedback Score: 0 reviews
 
Threetango's Avatar
 
Join Date: Aug 2012
Location: South Carolina, a gun friendly state.
Posts: 2,416
Liked 4418 Times on 1489 Posts
Likes Given: 1358

Default

I've had no problem shooting both 308 and 7.62X51 in my Bushmaster MOE 308 and according to Bushmaster it's fine.

__________________

NSDQ

Threetango is offline  
 
Reply With Quote
Old 10-31-2012, 09:33 PM   #16
Feedback Score: 0 reviews
 
Join Date: Aug 2011
Location: nowhere,that other state
Posts: 944
Liked 319 Times on 197 Posts
Likes Given: 399

Default

Quote:
Originally Posted by Yunus View Post
If I am not mistaken I believe another difference is the method used to measure pressure is different for the american specs (.223, .308) than for the european specs (5.56, 7.62). This means the numbers are not an apples to apples comparison.
Pressure in psi (Pounds per Square Inch) is the same no matter who measures it. Now if one were cup and one psi then yes. There is no formula to derive one from the other.

CUP = Copper Units of Pressure.
__________________
gunnut07 is offline  
jpattersonnh Likes This 
Reply With Quote
Old 11-01-2012, 12:26 AM   #17
Feedback Score: 0 reviews
 
jpattersonnh's Avatar
 
Join Date: Apr 2007
Location: South central,NH
Posts: 4,922
Liked 672 Times on 462 Posts
Likes Given: 677

Default

Quote:
Originally Posted by gunnut07 View Post
Pressure in psi (Pounds per Square Inch) is the same no matter who measures it. Now if one were cup and one psi then yes. There is no formula to derive one from the other.

CUP = Copper Units of Pressure.
The man has a point! The fomulas that try to change CUP to PSI, or visa versa just don't work.
__________________

Freedom is not free. The best of us always leave too soon.

jpattersonnh is offline  
 
Reply With Quote
Old 11-01-2012, 12:31 AM   #18
Feedback Score: 0 reviews
 
Yunus's Avatar
 
Join Date: Jan 2009
Location: |,Maryland
Posts: 4,715
Liked 1038 Times on 613 Posts
Likes Given: 319

Default

Quote:
Originally Posted by gunnut07 View Post
Pressure in psi (Pounds per Square Inch) is the same no matter who measures it. Now if one were cup and one psi then yes. There is no formula to derive one from the other.

CUP = Copper Units of Pressure.
WHO is not relevant to the measurement but WHERE is a very important factor.

http://guncentral.net/Articles/SAAMIvsNATO.html
Quote:
Test barrels made for 5.56 mm NATO measure chamber pressure at the case mouth, as opposed to the SAAMI location. This difference accounts for upwards of 20,000+ psi difference in pressure measurements. That means that advertised pressure of 58,000 psi for 5.56 mm NATO, is around 78,000 psi tested in .223 Rem test barrels (SAAMI .223 Rem Proof MAP is 78,500 psi so every 5.56 mm round fired is a proof load, very dangerous).
__________________

"Good people drink good beer."
Hunter S. Thompson

Yunus is offline  
 
Reply With Quote
Old 11-01-2012, 12:53 AM   #19
Guest
 
Posts: n/a
Default

I don't worry about it any more. I sold my .308 and bought a Remington Model 722 bolt action in .300 Savage. I love the older cartridges that everyone at the range does not have. I get sub-moa accuracy from this old rifle at near .308 velocities. I make brass for it from .308 brass, and it is very easy to do. Just an old fart having fun.
cottontop

__________________
 
 
Reply With Quote
Reply

Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Firearms Forum Replies Last Post
First rifle for an adult.. just for shooting fun rog1311 General Rifle Discussion 12 02-22-2012 01:03 AM
7.62x51 howquig General Rifle Discussion 15 11-17-2009 07:53 PM
.308 or 7.62x51 FCross7 Ammunition & Reloading 2 07-29-2009 11:13 AM
.308 vs. 7.62X51 9RobertJ Ammunition & Reloading 12 03-26-2009 11:01 PM
WTS:7.62x51/308 Training Ammunition 500rnd.Case $105.00,7.62x51/308 DAG Blanks $55.00 Cope's Distributing Sponsor Display 1 03-24-2009 03:46 PM