Throat location help!

[DennisPA]

I am getting a barrel built for a long range bench rest rife. I plan to use a "heavy for the caliber" bullet a Berger VLD, so I will be single loading and I am not concerned with cartridge overall length. My question is while I have the chance to move the throat I'm wondering if I should and how to determine how much.
I have made some dummy rounds putting the junction of the boat tail at the junction of the case shoulder to case neck. Since this is a new round for me and there is not a lot of data out there for it, how do I determine how far out to put the lands? Should tell the barrel manufacture dummy round plus .020 thousands of an inch and call it a day? Thanks for any help.

 

[Damascus]

Throat length will be set when the chamber is being finished.
You probably won't want a .020" jump using Berger VLDs. In most instances, they shoot best with jammed into the lands, or at least "kissing" them.
I would have my chamber cut to standard specs, then load some rounds long enough to where the ogive is contacting the throat - then test.
You can always buy a throat reamer and lengthen your throat yourself, by hand... But once you deepen it, you can't go back.
Having a chamber with a standard length throat may require you to seat the bullets so deep into the case that accuracy suffers - in that case, lengthen the throat .010" and try again, always recording your results.
Just let your barrel maker know the bullet you intend to use, and almost certainly, they will have a good starting point for you. Unfortunately, Berger VLD's are unpredictable from rifle to rifle (in my experience anyways), and what works in one chamber may not work in another.

 

[Hired Gun]

I always specify Saami spec chambers and the Bergers work great. I load them to feed and never a thought to the jump to the rifling as long as I'm at least .015" off the rifling. In the RUM and Weatherby chambers they jump a mile and shoot great. Get them too close and pressures can fluctuate wildly and accuracy goes to pieces.

 

[shortgrass]

Throat length will be set when the chamber is being finished.
You probably won't want a .020" jump using Berger VLDs. In most instances, they shoot best with jammed into the lands, Unfortunately, Berger VLD's are unpredictable from rifle to rifle (in my experience anyways), and what works in one chamber may not work in another.

Funny,,, my 6XC will land one on top of the other with 108g. Target when loaded .020" short of the rifling. There are few "absolutes" when it comes to rifles and loads. Start with a SAAMI speced chamber and go from there.