Maine Shooter

Hoe bout that mighty big .44 mag really being just a mere .429

thndrchiken

Let's not even get started about 7.62 or .308 and .311

bigbulls

7.62mm just happens to be exactly .300 inches which is the bore diameter (rifleing to rifleing)of a 30 caliber barrel.

.308" is the groove diameter of a 30 caliber barrel.

.311" is the groove diameter for a .303 brittish which has a bore diameter of .303".


Guys, it's really not that hard to figure out.Most numerical designations for cartridgesactually have a reason for their names. There are exceptions like the .325WSM and 44 magnum and 444 marlin.

SwampCollie

Ah Ha! A like minded indivdual who fell for the gestapo's trap and purchased the .325WSM.

Now, the debate rages on...is it a .323 (8mm)or a .330/.338?

Mr. Longbeard

Sounds like someone has to much free time on there hands...

eldeguello

Well, there's certainly alot of confusion when it comes to cartridge nomenclature. So I suppose thare has to be a way to try to differentiate between cartridges, and using names like ".270" when the bullet diameter is .277"-.278" is one way.

Many calibersare designated by their bore diameter-the size of the hole down the barrel BEFORE the rifling grooves are cut. Examples of this include the .270, the .30's and .300's, etc.But what you are proposing is simply the use of the inside diameter of the barrel after the grooves are cut, or the dimaeter of the bullet, which is usually the same thing.Examples of this are the various .308's, such as the ".308 Winchester", ".308 Norma Magnum", etc. So in fact both sustems are in use in the U.S.

In addition, we have some cartrtidges that we designate using their European names, which are metric. For example, the 7X57mm Mauser, etc. (Which in England is often called the ".275 Rigby").

At the present time, I believe we should leave well enough alone, and call the .270 Win., etc., by the names they have now. To change them now, after all these years, would just result in even more confusion than we currently have! particularly since arms companies insist on introducing new cartridges that are really unnecessary, like the .30 Marlin (or is it the.308 Marlin, or what??)

eldeguello

No debate at all! The "325" WSM is an 8mm, just like the 8X57JS. BOTH fire bullets of .323" diameter...... Which, BTW, is one damn good bore size, despite the fact that most Americans have refused to admit this, starting around 1917.....

thndrchiken

My point was in reference to the 7.62x51 ( 308 win ) and 7.62x 39. Two different size bullets.

bigbulls

Depends on who is loading it and who is making the gun.

But yes, originally they were different.

I have never measured the bore diameter of a true 7.62X39 barrel but it may be .300 inches also but have deeper grooves cut in it to get to .310 inches.

Knightia

I have heard of those diffences in 30 cals.We do have 3 chinese made 30.cals but no way of measureing the barrels i dont think- that i know of(i dont think my micrometer would work?). But they yep do have slightly bigger bullet/diameter- depending on whos making them i agree (99% of all ammo used in them was either chinse or ruski).

How Hornady( minesa little older manual)puts it is thisway - Foreigen produced firearms have a .311 bore - to use .310 diameter bullets.( what they call bore in there book anyways there saying is .311) Also stating that Rugers mini 30 is based on a .308 bore.And that There dies come with various expanders to use with the diffent bullet sizes. (i have never loaded the 7.62 x39)

Yet Hornady lists the 7.62 russian(7.62x 54R) for use with .308 bullets...(no bore size given)

I understand what youall are saying though about the 2 diffent barrel measurements - one each taken from the high& low points ( so does that mean in that first example 7mm barrels are aways cut deeper then -270,s?)



Buy yep math was never -ever my strong point& with old age i aint cant remember numbers etcfor dodo


Heard of those 38,s - are more 36,s?

In my 357/9mm blackhawk convertable- 9mm jacketed bullets have not ever shot very well when i tryed them.


Whatswith the 32-20 winchester - it lists bullets in a range of .308- .312 for use.

Why isnt it a 30-20?