# Overbore?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by benzh, Sep 28, 2003.

1. ### benzhNew Member

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4
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Feb 9, 2003
Is there a formula that can be used to quantify the degree a catridge is "overbore"?

Thank you

2. ### Varmint HunterWell-Known Member

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2,735
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Dec 26, 2001
Here is my formula:

If the largest safe charge of the slowest practical powder, in a given cartridge, does not fill the case to the bottom of the neck, than it is OVERBORED.
VH

3. ### DANTECWell-Known Member

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390
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Jul 6, 2002
commun formula is V = 1000 d²

but shape of case can make difference short fat case with sharp shoulder are more efficient ex :

6 Norma BR compare to 243 WIN
22 Dasher comapre to 22.250 Rem

basic idea is when you reach max water capacity for one caliber exemple 70 grain of water in 6.5 cal if you go over your gain in velocity became low compareto the increase of powder volume and if you go to extreme you sometime lose velocity or burn powder for nothing
exemple :
7 STW and 7/378 Wea

so except for fun or fashion better to use a longer barrel than a hudge quantity of powder and avoid by this fact carbon fouling effect wich is very commun with real overbore cartridge

good shooting

DAN TEC

4. ### benzhNew Member

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Feb 9, 2003
DAN TEC

re commun formula is V = 1000 d²

Does "V" = Velocity?
What does "d" represent?

Also can you give me an example formula for a .308 Winchester load vs. a 300 Ultra Mag? It seems that there should be some logic about the term that can be quantified.
Thanks
Howard

5. ### DANTECWell-Known Member

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390
Joined:
Jul 6, 2002
v is volume in grain
d is bullet diamter in inch

good shooting

DAN TEC