COL measure advice

[Shootist]

I seem to have a bit of a problem with the Hornady COL gauge, as follows. When pushing the bullet towards the lands I can feel first a very slight resistance, then if I apply more pressure, a distinct 'surge' forward for a short distance. At the first 'stop' if I remove the bullet, there appears to be no engraving of the rifling.This hasn't really troubled me too much as most of my rifles are Military, and throated as such, but with my newly acquired Savage F/TR the throat appears to be very short indeed, and this dual measure seems significant. I've spoken to other members of my club who also have noticed this double stop, so I don't think I have a duff gauge. The thoughts and opinions of the illuminate here would be welcome.

[Jagged 77]

 

 

A picture is worth a thousand words!

[Shootist]

Edit: double post

[Shootist]

Edt: Yet more finger trouble!

 

[Shootist]

 

 

A picture is worth a thousand words!

The picture is good, but a few words might help too. Thanks in any event for the picture. If I'm getting it right then it's the second shove measure that's to be used for COL decisions. Given the possible consequences of getting it wrong, some reassurance would help. If I'm getting this right, the first resistance is the start of the throat, so it's the second and final resistance that gives the measure to the lands or rifling?

[Jagged 77]

Hopefully a smith will chime in with their take on it for you, but the first resistance as far as I'm concerned is the throat. When you reach a solid stop with the gauge that's when you have reached the rifling. To avoid doubt use a permanent marker on the bullet to see where and how it has made contact with the throat and lands. I have a few rifles that I have the same issue on - one chambered in .260 by Baldie and the other a .338 by Osprey Rifles. My factory AX also is a bit tight in the throat area.

 

Edit to add, if you start at the rifling, start low and work up. Jamming acts to increase initial pressure - jumping acts a little as a buffer allowing pressure to build as the bullet moves forward into the rifling.

[Shootist]

Hopefully a smith will chime in with their take on it for you, but the first resistance as far as I'm concerned is the throat. When you reach a solid stop with the gauge that's when you have reached the rifling. To avoid doubt use a permanent marker on the bullet to see where and how it has made contact with the throat and lands. I have a few rifles that I have the same issue on - one chambered in .260 by Baldie and the other a .338 by Osprey Rifles. My factory AX also is a bit tight in the throat area.

 

Edit to add, if you start at the rifling, start low and work up. Jamming acts to increase initial pressure - jumping acts a little as a buffer allowing pressure to build as the bullet moves forward into the rifling.

Thanks for that. Very reassuring to a) know the right answer, and that someone else has noticed.

[Tony.H]

the double resistance you talk of, i found it is when you have the bullet drop in, too far inside the brass, so when you push on the back of the rod it, shoves the bullet at an angle against wall of the case first, i had the same thing happening to me, so i just started the bullet futher out the case, or just tilt the rifle down a tad, so that the bullet just slides in the lands, then i push the rod forward feeling for the resistance, hold it there tighten up the brass screw and remove the case and the bullet, i repeat this a few times just to make certain.......

 

 

tony

[gunner]

second the permanent marker , you can see where the bullet has touched the lands around the cercumfrance of the bullet :)atb ... tim...

[jcampbellsmith]

For a given type of bullet, I'll generally measure five or six different bullets and take the average as my nominal OAL for that bullet. Regards JCS

[CCH]

For a given type of bullet, I'll generally measure five or six different bullets and take the average as my nominal OAL for that bullet. Regards JCS

 

 

This is good practice----^

 

It can aso be worth ( Maybe) sorting bullets by overall length to ogive using your comparator first if you are aiming for precise seating depths. I have found that sorting 200 grain Nosler accubonds in 30 cal to have improved consistency in my .30-06 or example.

 

In answer to your question you want to use the most repeatable point for your measurments, irrespective o where exactly that puts the bullet in realtion to the rifling. In practice this wil be the second point you mention and a combination of the gauge and a marker pen will show you what is happening at this point.

[Dark Star]

I've also found that the modified case supplied with the gauge can require its neck to be tweaked so it allows the bullet to slide in and out easily. Depending on the dimensions of your chamber, you may need to turn the outside and/or work on the inside of the neck with some emery paper.