C.O.L. and manuals

[Sitting Bull]

Hey guys, as a fairly new reloader, I am finding discrepancies is suggested col in different manuals. ex: I am loading up .270 with 54grs of IMR 4350 and 130 gr Hornady Interlock Sp bullets.
The Hornady manual says C.O.L. 3.210 " Lee manual says 3.340" max, Lyman says 3.250",Hodgdon Reloading manual says 2.730".
So why the differences between them all? If these are to be max C.O.L. who is right?
Thanks for the help guys.

[elkhunter11]

The best thing that you can do, is to ignore the COLs listed in manuals, and base your COL on your firearms. Measure the distance to the lands with your bullet, and start out .010" to .020" off of the lands, as long as this will fit the magazine and cycle through the action. For monometal bullets, start out at. 050" off of the lands.

[Sitting Bull]

Thanks Elk, I am shooting out of a break action single shot.

[elkhunter11]

One more thing to watch out for, is that you have enough bullet shank in contact with the case neck. The general rule is one bullet caliber, but I often use less. It's usually only a concern with a long throat, and boat tailed bullets.

[Sitting Bull]

So I figured out the number to the lands. It comes out at 2.261" 5 times in a row.
I will seat three bullets at 2.259" three at 2.258" and three at 2.257 and see which shoots most accurately. Is this correct?
Now what about crimping? I am no where near a cannelure . By the way this is a flat base bullet if that matters.

[Dick284]

Originally Posted by Sitting Bull

So I figured out the number to the lands. It comes out at 2.261" 5 times in a row.
I will seat three bullets at 2.259" three at 2.258" and three at 2.257 and see which shoots most accurately. Is this correct?
Now what about crimping? I am no where near a cannelure . By the way this is a flat base bullet if that matters.

You are going in too small of steps.
Go in 0.005" minimum.
2.255"
2.250"
2.245"

Hold your calipers up to the light at an opening of 0.005" you'll see how small that is.

I also will point out that you'll be seeing that much error in your loaded rounds too.

I feel it's more to do with setting your combustion chamber for an optimum burn scenario, as opposed to jump to the lands. Think of the lands as trying to catch that boil of mirage on the road in the summer, it's always there taunting you to try and catch it, but it's forever moving.

Don't crimp.
Don't worry about where the cannelure is.

Don't sweat the small stuff, sometimes simpler built bullets(flat base, round nose) will shoot lights out better than low drag, secant ogive, dual core, mono metal, poly tipped wonder bullets. KISS.

[Sitting Bull]

Originally Posted by Dick284

You are going in too small of steps.
Go in 0.005" minimum.
2.255"
2.250"
2.245"

Hold your calipers up to the light at an opening of 0.005" you'll see how small that is.

I also will point out that you'll be seeing that much error in your loaded rounds too.

I feel it's more to do with setting your combustion chamber for an optimum burn scenario, as opposed to jump to the lands. Think of the lands as trying to catch that boil of mirage on the road in the summer, it's always there taunting you to try and catch it, but it's forever moving.

Don't crimp.
Don't worry about where the cannelure is.

Don't sweat the small stuff, sometimes simpler built bullets(flat bare, round nose) will shoot lights out better than low drag, secant ogive, dual core, mono metal, poly tipped wonder bullets. KISS.

Great Stuff! I don't know what I was thinking. I was trying to split gnats hairs.

[Dick284]

Originally Posted by Sitting Bull

Great Stuff! I don't know what I was thinking. I was trying to split gnats hairs.

Ya don't say

[Sitting Bull]

Thank You !