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CajunJedi
November 14, 1998, 02:31 AM
Today I was fooling around studying my rifle and I noticed something I think is a little odd. When I tried to see if the tip of a .300 Weatherby bullet (yes the bullet not the case) it would not fit inside the muzzle of the rifle. The bullet would only fit about halfway in the muzzle, then would go no farther.

It seems like this would really affect the velocity of the bullet and slow it down very much. Is this true?? I know for a fact I have the right ammo for the right gun......but why is the actual bullet larger than the barrel at the muzzle??? It would seem like the barrel needs to be a little wider than the bullet itself.

Sorry if this is a stupid question, but any info would help. Thanks.

CajunJedi.

.
November 14, 1998, 04:14 PM
CajunJedi,

The bore of your barrel is actually lined with a series of lands & grooves. It's cross section appears as a "gear shaped hole". The bullet actually distorts and is molded to the "bumps" and "dips" to form a metal to metal seal, so that the hot expanding gases behind it cannot escape past it. That gas pressure building up overcomes the initial friction and moves the bullet forward. As it moves in the bore, the heat from the friction causes it to soften a bit and allows it to flow and accomodate the lands & grooves with an even better seal. The heat also liquifies the outer molecular layer of bullet metal and allows it to "slip" down the bore even faster, up to the point that the gas pressure behind it begins to drop off.

This leads to at least two results:
a) the impression of the bore on the bullet, which is used in forensic science to match the bullet and the barrel.
b) the implication that there is an optimum barrel length for a given bore/cartridge combination.

If your bullet had dropped thru the bore as you'd originally expected it to, then the bore was either "blown out" (eroded) or you had the wrong diameter bullet.

Hope this helps, as it is really only the "tip of the iceberg".


[This message has been edited by Mykl (edited 11-14-98).]

Doc Lisenby
November 26, 1998, 12:12 PM
Cajun, Mykl explained it well. Now to get a little technical to maybe help clarify it a little. The bullet (projectile) in the 300 Wby is .308" in diameter. The barrel is approximately .304" in diameter between the lands and approximately .308" in diameter between the grooves. If you try to figure all firearms this way it won't work; some are downright dumb. You owe me some of those delicious crawfish and alligator tail. Doc