i can't find good answer. are these really interchangeable? as in can i shoot both in a sig 716? or in a cet?

They are not interchangeable...at all...

 

Unless the rifle has been proofed for both

3 minutes ago, CAL. .30 M1 said:

They are not interchangeable...at all...

 

Unless the rifle has been proofed for both

thank you. so essentially, if the rifle's stamped for 7.62 onlyrun that, and vice versa.....

 

 thank you man. appreciate the quick answer.

20 minutes ago, CAL. .30 M1 said:

They are not interchangeable...at all...

 

Unless the rifle has been proofed for both

That's a bit misleading.

Cartridge dimensions are identical.  .308 is higher pressure than 7.62x51.

Basically, a firearm designed for .308 can handle either .308 or 7.62x51 (AKA 7.62 NATO).

A firearm designed for 7.62x51 should only fire 7.62x51.

More details:

https://www.shootingillustrated.com/articles/2018/8/19/308-win-vs-762-nato-whats-the-difference/

 

Quote

The actual pressure differences between aren’t all that large—a 62,000 psi limit for the .308 Win. and 60,200 psi for the 7.62 NATO—but it’s enough to be concerned with; a tight chamber, or an overly dirty chamber could pose a pressure issue. No one wants to damage a firearm, and we certainly don’t ever want to see anyone hurt; so keep the golden rule in mind: a .308 Win. chamber can handle both .308 Win. and 7.62 NATO ammo safely, but if your rifle is marked for 7.62 NATO ammo, it’s best to use only that.

 

2 hours ago, DirtyDigz said:

That's a bit misleading.

Cartridge dimensions are identical.  .308 is higher pressure than 7.62x51.

Basically, a firearm designed for .308 can handle either .308 or 7.62x51 (AKA 7.62 NATO).

A firearm designed for 7.62x51 should only fire 7.62x51.

More details:

https://www.shootingillustrated.com/articles/2018/8/19/308-win-vs-762-nato-whats-the-difference/

 

 

That's is my understanding, as well. 

4 hours ago, DirtyDigz said:

That's a bit misleading.

Cartridge dimensions are identical.  .308 is higher pressure than 7.62x51.

Basically, a firearm designed for .308 can handle either .308 or 7.62x51 (AKA 7.62 NATO).

A firearm designed for 7.62x51 should only fire 7.62x51.

More details:

https://www.shootingillustrated.com/articles/2018/8/19/308-win-vs-762-nato-whats-the-difference/

 

 

It is not at all misleading - at all - is the rifle is stamped 7.62 NATO fire 7.62 NATO - you also forget 7.62 CETME - Put a 308 in that - watch the fun !!

And you left out the balance of my statement - "unless it is proofed for both"

How many people put .308 in old RFI 2a or 2A1's and stretched the receiver - sure the round will chamber but that gun is lucky it can handle the 7.62 let alone .308

 

The problem is that most folks do not bother to know or care (not suggesting the OP) what goes on behind the scenes in the round.

Yes dimensionally they are the same - BUT, you did not mention that the MILITARY brass is much thicker than commercial brass as well - hence a loading in a commercial case has more room than a military case.

 

The absolute easiest rule of thumb - fire what the rifle is proofed/stamped to shoot.

 

Hence, if the rifle is proofed/stamped for 7.62 use 7.62 - if the rifle is proofed/stamped for .308 - fire 308 - KISS.

 

Now my M1A is proofed to 308 - but I fire factory 7.62 and handloaded 7.62 168Gr SMK

 

 

TO THE OP - they are NOT *easily* interchangeable.......and should not be considered to be so - IMO YMMV

2 hours ago, CAL. .30 M1 said:

It is not at all misleading - at all

Yes it is.  Your first post, taken alone, leads people to believe that there are no circumstances in which one caliber can be used instead of the other.

2 hours ago, CAL. .30 M1 said:

is the rifle is stamped 7.62 NATO fire 7.62 NATO - you also forget 7.62 CETME - Put a 308 in that - watch the fun !!

...

How many people put .308 in old RFI 2a or 2A1's and stretched the receiver - sure the round will chamber but that gun is lucky it can handle the 7.62 let alone .308

When did I suggest using .308 in a 7.62 anything?

2 hours ago, CAL. .30 M1 said:

Yes dimensionally they are the same - BUT, you did not mention that the MILITARY brass is much thicker than commercial brass as well - hence a loading in a commercial case has more room than a military case.

Covered in the article I linked.

2 hours ago, CAL. .30 M1 said:

Now my M1A is proofed to 308 - but I fire factory 7.62 and handloaded 7.62 168Gr SMK

So your M1A is proofed for .308, but not proofed or stamped for 7.62, but yet you use that round anyway?  Because you have enough information to make an intelligent decision? Like I was trying to provide in my earlier post?

4 hours ago, DirtyDigz said:

Yes it is.  Your first post, taken alone, leads people to believe that there are no circumstances in which one caliber can be used instead of the other.

When did I suggest using .308 in a 7.62 anything?

Covered in the article I linked.

So your M1A is proofed for .308, but not proofed or stamped for 7.62, but yet you use that round anyway?  Because you have enough information to make an intelligent decision? Like I was trying to provide in my earlier post?

You are missing the point....   do what you want

Give advice you want to give...I don't really care.

And you said it 11 hours ago...

However, for the general uneducated user ( not pointed at the OP )...yes my comment stands.

Until such time as they educate themselves...in depth, too little knowledge, following unsound advice, will get them hurt 

 

 

My 7.62 M14 eats ONLY Nato 7.62 Period.

I found an article on SOFREP that stated that the 7.62 NATO measurement is in CUP and that the difference in pressure between 7.62 and .308 is 58000 PSI vs. 63000 PSI, not a significant difference. 

 

"This is where things get a touch confusing. The maximum pressure numbers for these two calibers are typically shown to be around 63,000 PSI for the .308 Win and just 50,000 PSI for the 7.62. That may seem like a significant difference and grounds for people to think it an ill-advised move to fire a higher pressure .308 cartridge in a rifle that’s fitted for the 7.62 NATO. But hold your horses there, fella. It really isn’t that simple.

The truth is that that so-called 50,000 PSI is not accurate, at least not in terms of pounds per square inch. 50,000 is more accurate if you’re talkin’ copper units of pressure or CUP which is a whole other animal. CUP is an inferior method of measuring pressure which depends on looking at how tiny an amount of copper disks compress when you fire your weapon. The approximate difference between CUP and PSI works out to about 8,000 which I think we can agree is a giant leap in terms of rendering a precise figure.

To put it another way, the max pressure for the 7.62 NATO is somewhere closer to 58,000, placing it closer to the PSI of the .308 Win than one might be led to believe. The 4,000 difference is hardly a difference at all, at least not one that would disrupt the trajectory of a shot aimed at a sluggish boar."

Problem being, the possible variation in NATO 7.62 from various countries. Do I really want to try 308 on my 4K Texas Devine M14, or my 5 liner M14? NO.  Or my 2500 M1 Garand with 7.62 barrel? NO. 

13 hours ago, CAL. .30 M1 said:

However, for the general uneducated user ( not pointed at the OP )...yes my comment stands.

 

 

i am the uneducated user in this instance, so i get it, and am reading all of this.

 

5 hours ago, 1LtCAP said:

i am the uneducated user in this instance, so i get it, and am reading all of this.

^^^^^  this...

 

Read, dive deep...learn...

 

If you a general user that just wants to drop a round in to go boom.... follow the chambering on the gun

 

If you want to get to the ballistics behind it all...  well done....  then you can do the deep dive...

As well as semi version bolt...  rear locking lugs front lugs...safety lug no safety lug..etc.

Example

The ENFIELD RFI 2a and 2A1 are interim rifles to get the indians using 7.62 prior to FAL adoption -  that used .303 smle actions that have one lug ...  it is a 7.62 barrel on a .303 action....there are those that will tell you that 308 win is fine in it...  really?  

The headspace on the RFI's are all.over the place..generous chambers and mild ww2 steel 

They r lucky they can handle 7.62 let alone 308...  you. The internet is awash with those that say it is fine...me not so much

Remember this,  all it takes is One...only one detonation in front of your face to go bad to make a very bad day for you.

12 hours ago, antimatter said:

 

Watch this and learn something!!