Well I guess I have been lucky with mag lengths. I have 6 personal guns and in all of them I can load to the lands if I want and still fit the mag. Must confess that if I procure a rifle where that is not possible then I will get rid of it or custom rebarrel it to make it happen.
| shooter4 wrote:|
What method do you use to find the right COL (Cartridge overall lenght) for your rifle? Any good tricks for optimum length?
To me this is a 2 part question. The first is the mechanics of actually finding the COL. There are several tools to do this. The most common is the Hornady OAL Gauge
and you will need a modified case in your caliber
It is simple and foolproof (which helps me out) and you don't need to worry about the headspace difference between your modified case and your brass like you do with the Hornady. You just insert your bolt in your gun and make sure it is cocked (firing pin retracted), insert the rod into the muzzle to the bolt face and lock the rear collet
retract the rod, insert the bullet to the lands (hold in place with a dowel or use the Hornady tool if you have one), insert the rod to the bullet tip and lock the front collet
measure between the collets
I have tried the slightly tight neck and bullet method and the cleaning rod method and got inconsistant results either because of the bullet being pushed into the lands with different force or the lands grabbing the bullet and pulling it partway back out.
The 2nd part of the question is how to find the best length to seat the bullet that will give you the best accuracy in your rifle. That is pretty much trial and error but in my experience I just seat a bullet I am going to try out at .025" and vary the powder type and weights and usually find a good load before I have to worry about seating depth. However in my experience if you try to seat too close then you will have problems with more flyers when your COL varies. It is hard to seat a set of bullets without some variance, commonly .005" or so. So if you are seating .005" off the lands then some will be touching and some will be .010" off and accuracy will suffer. Bullets themselves are not always consistant in bearing surfaces, ogive curves and length (not to mention weight). If you back off then the seating depth variances will not have as great an effect as they have when seating close.
So if your magazine is restrictive, seat to fit the mag and vary the bullets, powders, primers and cases. If you can hit the lands, back off .025" for common bullets or .050" for monolithics like Barnes TSX, and vary the other factors.