Bullet Diameter vs. Caliber


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dedgunner
November 12, 2008, 10:59 AM
As a noob to reloading metalic I am wondering about the relationship of bullet diameter size to claiber. I have noticed that in searching for a 308 caliber bullet the sizes range from .307 to .309. Also will these same bullets fit any 30 cal cartridge 30-30, 30-06, etc. ?

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lordgroom
November 12, 2008, 11:45 AM
You will find information about bullet size in reloading mnuals. If I am at work and a manual is unavailable, I consult wikipedia.

RPCVYemen
November 12, 2008, 12:50 PM
Note that what is conventionally called "caliber" is only loosely related to bullet diameter. For example a 44 Magnum shoots a 43 caliber bullet.

The reloading manual is your friend.

Mike

rcmodel
November 12, 2008, 01:27 PM
At one time, 30-30 Win bullets were made in .307" by some manufactures. Maybe they still are?

But .308" is the correct size Jacketed bullet for almost any .30 caliber rifle, including the 30-30.

Cast Lead .30 cal bullets are often sized .309".

But the advice to buy a good reloading manual or two is very good.
Then read them cover to cover several times.

I especially recommend the Lyman manual for a complete understaing of cast & jacketed bullet sizes for all calibers.

interlock
November 12, 2008, 03:33 PM
"But .308" is the correct size Jacketed bullet for almost any .30 caliber rifle, including the 30-30."

i think that some bullets are very slightly bigger or smaller than others. I think nosler bullets are very slightly bigger than speers.

rcmodel
November 12, 2008, 04:48 PM
Not to confuse the issue, but Nosler doesn't say what their bullets measure.

They just say they are .30 caliber bullets.
Not .308", or .3085", etc.

interlock
November 12, 2008, 05:54 PM
RC,
you are right. the speer bullets i use are .308 i found that when loading the speer bullets easily slip through the seating die into the section of the die that actually seats the bullet (lee dies) but the noslers don't. they stick slightly which can be a pain because it pulls the bullet out of the neck sometimes. the noslers also get to pressure signs very early. i checked the box and it says 30 cal.

they are deadly accurate though

interlock

Hairballusmaximus
November 12, 2008, 05:59 PM
Manufacturers may vary the dia a thou or so possibly due to jacket thickness. A thick jacketed .308 may create too much pressure due to increased friction where a .307 will still bite the rifling and seal just fine while not increasing pressure. But this is just a guess.

Be careful of too much variance though. I have been told NOT to use the russian import 7.62X39 in american made guns due too larger dia bullet in the russian stuff. Winchester for example uses a .308 dia bullet and the russian stuff is supposedly .311

Walkalong
November 12, 2008, 07:55 PM
Some bullets have a "pressure ring" from the manufacturing process. They may be .308 for 99% of the bullet with a pressure ring at the base of .3085 or so. Most bulk bullets do not, but some do. Test some out. ;)

Japle
November 12, 2008, 09:06 PM
Much depends on your rifle. You have to try different bullets. The rules are variable.

In my Mosin Nagant M44, which should require .311 bullets, I have the best accuracy with 200 gr .308 Sierra BTs. Guess my M44 never read a loading manual.

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