Boy, Am I stumped

7.62x54r and .308 (7.62x51) are not interchangeable. x54r is rimmed, and has a much more tapered shoulder. (Never heard of 7.62x45, except the Czech mg round)

.308 winchester is closer to 7.62x51 NATO, not 7.62x54r. None of them are completely the same, but the nato round is often said to be interchangeable with a .308 win. I'm not saying to use them that way though. The 7.62x54r is not going to fit in a .308 win rifle. It's longer, and it's rimmed. .308 win and 7.62x51mm Nato are both rimless cartridges. Also, because Russia (whose guns usually but not always chamber the 7.62x54r cartridge) measures their bores differently than western countries, a 7.62x54r may have the same number represented (7.62) but it measures it across different parts of the chamber. Thus, the bullet needed to fill the rifle's bore diameter is larger than .308". Usually .311"-.312".
As for 7.62x45, I don't know exactly what it is but it sounds from your description like a .223 rem with a .308 bullet crammed down the neck of the case.
Hopefully I was helpful. Please check and recheck the chambering of your gun and match it with the head stamps on your cartridges before you shoot.

7.62x51 is the same as 308. people just don't realize that the metric pressures are measured in...that's right... metric and the american is measured in... you guessed it...'Merican. two names for a cartridge that is nearly identical and in truth fully interchangeable... gotta love the internet for perpetuating myths.

as for x54R, no the two are very different. one has a large rim like 45-70 or 303 british and is more tapered kindof like the 7.62x39 cartridge for SKS and AK47 rifles, only larger. it was used mainly in the mosin nagant rifles with some lesser known models like the dragunov, SVT38/40 and DP27. it is in no way interchangeable. even though the two have the metric measurement of 7.62mm, the russian uses a .311 diameter bullet while the US and NATO counterparts use a .308 diameter bullet. never try to shoot x54R out of a 308.

I've never heard of 7.62x45 ruger, can you offer a link? there is a 7.62x45 czech which had a very short service life and to my knowledge was only used in the VZ52 battle rifle.

Actually, the .308 Winchester's pressures are measured in Pounds per Square Inch (PSI) using modern strain gauges and computers. The 7.62 x 51's pressures are measured in Copper Units of Pressure (CUP), a method used and specified by the US military. CUP used to be the standard method of measuring pressure in a rifle or pistol, while Lead Units of Pressure (LUP) was used to measure shotgun pressure. Both CUP and LUP use lead of copper plugs that are deformed by chamber pressure & then measured to calculated their respective results.
The pressure measurement systems (CUP and PSI) do NOT correlate with each other, They do NOT read the same nor can they be compared to each other.
Using PSI, the .308 Win and the 7.62X51 are essentially identical. The only difference between them is minor chamber dimensions (looser) for military weapons and slightly thicker brass (again for military weapons such as machine guns with VERY loose chambers.)
The above is not true for 5.56 x 45 vs the .223 Remington, they in fact are loaded to different pressure levels.

Roger

velocette said:

The above is not true for 5.56 x 45 vs the .223 Remington, they in fact are loaded to different pressure levels

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The 5.56 and 223 Remington produce similar pressure levels when fired in their respective chambers. The difference in is that the pressure of the 5.56 increases when fired in a 223 chamber and the pressure of the 223 drops when fired in a 5.56 chamber

7.62x54R is closer related to 30-06 in terms of energy than .308WIN/7.62x51. Hence why a Mosin Nagant is often called a "$100 30-06 rifle." 7.62x45 is "new" to me as the only firearm I know that uses it is eastern bloc crew served weapons with no western nations picking it up. Ruger, being an American company, rarely measures a caliber in metric so you might have confused some numbers.

Never heard of 7.62X45 nor can I find anything about it on Rugers website. Sure you are not confusing it with something else.

7.62X51 and 308 have been used interchangeably since the beginning with no reported issues. Same with 223 and 5.56. It wasn't until the internet that some folks discovered that just maybe there might be a slight difference in pressures and chamber dimensions.

Guess what. You will find just as much variation in pressures and in chamber dimensions if you go out and test several batches of ammo or guns chambered in any other cartridge.

You are just as likely to run across a batch of 243, 7mm magnums, 270's or 30-30's that are going to be a little hotter than normal in some guns as you would between 223/5.56 or 308/7.62X51.

It has always been that way. The manufacturing tolerances for guns and ammo is just as great as the differences between the military and civilian designations for the above rounds.

If we used the same criteria for 30-06 we should have at least 3 maybe 4 different names for the round depending on the pressures it is loaded to.

Trying to figure out why a cartridge is called what it is will give you brain damage. However, a 7.62 x 54R's bullet isn't 7.62mm or equal to the .308. It uses a .311" bullet(despite what Hodgdon thinks) at roughly .303 British velocities(2400ish fps, depending on the bullet). Mind you, 7.62mm doesn't mathematically convert to .308" either. .308" converts to 7.82mm. 7.62mm is the bore diameter, everything else being equal.
The 7.62 x 45 had nothing to do with Ruger. Czech MG cartridge.
"...metric and the American..." No such thing as American units of linear measure. Metric and Imperial only.
"...the .308 Win and the 7.62X51 are essentially identical..." Before there was such a thing as the Internet, they were identical. So was the .223 and 5.56 NATO.

NO the 308 is not even close to the 7.62x54r

308 is a little faster than the 7.62x51 round and a little higher pressure. Just the opposite from the 223 and 5.56x45. Do Not fire the 308 in mil spec WWII rifles.

A modern version of the 7.62x45 would seem to be a mystery round.

CALAVERASSLIM Where did you find that 7.62x45 cartridge from ruger .

Do Not fire the 308 in mil spec WWII rifles

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and just what WWII military issued the 7.62 NATO cartridge? this made me lol.

and just what WWII military issued the 7.62 NATO cartridge? this made me lol.

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They are probably talking about the WWII surplus that were converter over later like some Spanish Mausers.

The only "Interchangeability" you will find with ..308 , 7.62X54r, 7.62X51 wioll be selecting the range, the animals and the effect you want down range.

The X54r and the X51 cases, bullets, and primers wont interchange, being that cartridges are rather precise in measurements, its that apon shooting, the bullets being in nearly the same size and speed bracket, the effects of useing such are close.

Basicly , if you can use a X54r on a target/animal/human, you can do the same with X51 and vice versa

7.62X45 was a Czech round used in the Cz 52 'She' rifle and their Vz 58

This link discusses the difference between .308 and 7.62x51
I found it useful in understanding those issues.

http://www.303british.com/id36.html

A 7.62x54R cartridge, is a Lower pressure cartridge than the .308, 7.62x51 and .30-06.( 45,000 CUP for the 7.62x54R Vs 50,000 + for the .308 ,7.62x51 and .30-06)
But Volocities are close ,even at lower pressures.
But it can be loaded to higher pressures to maximize it's performance in a rifle that is designed to hold those pressures.
A Mosin Nagant is Not designed for the higher pressures.

caribou said:

The only "Interchangeability" you will find with ..308 , 7.62X54r, 7.62X51 wioll be selecting the range, the animals and the effect you want down range.

The X54r and the X51 cases, bullets, and primers wont interchange, being that cartridges are rather precise in measurements, its that apon shooting, the bullets being in nearly the same size and speed bracket, the effects of useing such are close.

Basicly , if you can use a X54r on a target/animal/human, you can do the same with X51 and vice versa

7.62X45 was a Czech round used in the Cz 52 'She' rifle and their Vz 58

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Assuming you mean the CZ52 semi-auto handgun, that would be a 7.62x25 Tokarev, which is a Russian bottlenecked handgun cartridge.

Never heard of a 7.62x45. The rest of the thread contributors appear to have set the OP straight on what interchanges and what doesn't.

Wikipedia shows a 7.62x45 is a rifle cartridge for the VZ52 rifle. http://en.wikipedia.org/wiki/7.62%C3%9745mm_vz._52 But this isn't the same as a CZ52 obviously.

tahunua001 Yea your right , did not make war time in ww2 but was devolved in the grand design before wwII but the old standard 06 made the carry over . Just had to wait for nam.

Calaverasslim Most of use are getting old. Your hang'un with good company.

Thanks for asking this question Ive wondered about it too.

The 7.62x45 is a great round for the VZ52. It never got beyond the prototype stage for the VZ58 (ie not fielded).

I saw a '52 back in the 90s. The owner was angry he could not get ammo for it.

Mike

Sunray said:

"...metric and the American..." No such thing as American units of linear measure. Metric and Imperial only.

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Quibbling here, but actually you're the one who's wrong on this point.

http://en.m.wikipedia.org/wiki/Comparison_of_the_imperial_and_US_customary_measurement_systems

For what it's worth, the system of measurement we use is not properly called the 'imperial' system anymore, as that system was based on more or less arbitrary physical criteria. And since 1959, our standard for length has actually been a derivative of the Meter, so really there's only the Système Internationale, and a largely retarded and anachronistic way of stubbornly trying to pretend SI doesn't exist or is inferior, somehow. And that may as well be called the American system, anyway, because we're the only country left using it in any significant form. It's truly 'exceptional' (which should be read the same way we call certain people 'special').

Though it's funny buying plywood in Europe, because the sheets are all still 4ft x 8ft, and don't conform to any even metric increment.

There's one UK company I work with that has an interesting product where the product is sold in half meter increments- one can buy a 1 meter section, a 1.5 meter section, a 2 meter section, etc… But the welding that makes up the assembly is actually done in decimal feet. In other words, the foot is divided into 10 'inches', instead of 12. Which makes integrating it into American construction projects very entertaining.

LemmyCaution said:

And that may as well be called the American system, anyway, because we're the only country left using it in any significant form.

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Actually..it is still used by the British very regularly. Their speed limits are posted in mph not kph.

British people still use the Imperial system in every day life even if many other official uses are metric.