COL?

[G33InMyPocket]

I tried searching, and I'm sure it's been asked before, but what do you use for a COL? I have the Lee modern reloading book and Mettalic catridge reloading and they list the Max overall length and the Min overall length for each finished cartridge but not what to use for a COLon the cartridge. Do you just pick a number in between the min and max or something? I read in the back of the Lee book "best accuracy is usually obtained with bullets seated at the maximum overall length and factory crimped."
Any help greatly appreciated. Thanks.

 

[brickeyee]

Below the min indicated is likely to produce higher pressures than anticipated by the loading manual.
Longer than given may not fit in some magazines (but may fit in yours).

 

[G33InMyPocket]

So basically anywhere in between the min and max?

 

[scrat]

yes and no.

You see you need to set a standars of uniformity when loading. Try to set your depth to a certain number then maintain at or around that length. For a new load you that you have never tried you may extend the col to optimize on pressure. When increasing powder charge you can reduce the COL but must stay within specs.

 

[Ol` Joe]

You need to find the point the bullet will contact the rifleing and seat the bullet "just to", or below this lenght. The bullet touching will raise pressure over the bullet haveing a little jump, this lenght also risks the bullet sticking in the throat of the rifle and pulling out of the case if the rifle is unload with a live cartridge in the chamber with a hunting rifle. I use this COL for load work up only!
I set my COL to have the bullet at this just touch lenght and work up my load with it in this position. I then, after determining my max, check the COL for compliance with SAAMI max lenght and if too long seat to the SAAMI max lenght and check for accuracy. I then "tune" the load by reducing the COL in 0.005" increments until acccuracy improves or I feel I am seeing accuracy deteriorate and call that the COL I want my load set at. I also use a comparator tool to measure this COL off the ogive as the tips will vary with each bullet seated giveing false measurments. The next bullet brand or type I experiment with will start out seated to this prefered lenght to ogive and the load worked up around that COL.

 

[brasskeeper]

I Start with what they call "jam Length". I take a fired case and start a bullet into it. Then I place the case in the chamber and close the bolt. When I extract it I measure the OAL and this will be my jamb length. I seat the bullet a couple thousanths deeper then darken the tip of the bullet with a match and put it back in the rifle and close the bolt. When I extract the case if there no scratches on the tip of the bullet in the darkened area this is my max over all length provided it is not to long for the magazine. If there are scratches I seat the bullet another thousanths deeper and try again.

This is my method and it works for me. You can by tools to measure from bolt head to the riflings if you want.