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swmike · May 13, 2008, 08:18 PM

Vihtavouri likes real long COL's for some of their powders. I load VV3N37 and they spec 1.142" using a 124gr JHP. If follow this my CZ won't go into battery. I have to shorten the cases to 1.125" which works great in both my CZ75 SP-01 Tac and my Sig P-229.

If you want to find the longest COL that your pistol will accept, take a case that has been trimmed to .750" (Design Std for this round). Insert a bullet in the unloaded case leaving it extra long, drop it into the chamber and press in until the case mouth engages the front of the chamber (where it headspaces). Remove the bullet/case assy and measure. Subtract .005" from this measurement (for freebore) and THAT is the longest round (using that bullet) that will fit. Then make sure it will fit in your magazine. If so, it probably will be very accurate as well as the bullet is not wobbling around in the chamber a lot before it engages the rifling.

Beware of MINIMUM COL's as they are there to prevent extreme case pressures by squeezing the charge too much.

May 13, 2008, 08:18 PM	#8
swmike Senior Member Join Date: June 25, 2005 Location: Marysville, WA Posts: 670	Vihtavouri likes real long COL's for some of their powders. I load VV3N37 and they spec 1.142" using a 124gr JHP. If follow this my CZ won't go into battery. I have to shorten the cases to 1.125" which works great in both my CZ75 SP-01 Tac and my Sig P-229. If you want to find the longest COL that your pistol will accept, take a case that has been trimmed to .750" (Design Std for this round). Insert a bullet in the unloaded case leaving it extra long, drop it into the chamber and press in until the case mouth engages the front of the chamber (where it headspaces). Remove the bullet/case assy and measure. Subtract .005" from this measurement (for freebore) and THAT is the longest round (using that bullet) that will fit. Then make sure it will fit in your magazine. If so, it probably will be very accurate as well as the bullet is not wobbling around in the chamber a lot before it engages the rifling. Beware of MINIMUM COL's as they are there to prevent extreme case pressures by squeezing the charge too much.