Weatherby 30-378 Seating Depth Help, PLEASE

TX mountain hunter

Well-Known Member
Dec 17, 2010
West Texas
I have a custom rifle chambered in a 30-378 Weatherby. I'm looking at loading up some 200 grain Barnes LRX bullets, but am wondering what depth will touch the lands. I don't have an OAL gauge and have always had trouble trying to find the lands on my own. What would be the seating depth required to touch the lands for this chambering? I'm magazine restricted to 3.845", which I'm assuming isn't too bad from what I've read on this caliber. I would like to start with some load testing around 0.030" and 0.070" as barnes recommends for maximum accuracy.

Every gun is different. Either buy a tool to measure or seat the bullet long and keep bumping it shorter untill it fits. I take the bolt apart on all of my guns to get rid of any spring tention to help me feel when the bullet hits the lands. You say "custom rifle"....what brand is the action? Did you get the freebore specs from your smith?
I don't have the brand of the action or the specs since I bought the rifle used. I was told that it was chambered to factory 30-378 specs just with a larger mag box. I thought that that would mean the distance to the lands would be the same or at least close in all 30-378 WBYs. I was just wondering if there is a way to calculate it or if someone had already measured the 200 LRX is this chambering.

Thanks for the tip on the bolt, I'm not sure what you mean by relieving the spring tension though (still a rookie).
If its chambered to the factory specs it will have a lot of freebore, i load this same bullet to 3.780" in my sotck accumark as this is as long as the magazine will allow....I do have an OAL guage and seem to remember trying to measure it once and remember thinking it would be really hard to get the bullet to touch the lands in my rifle.....nonetheless it's pretty important as seating depth can affect pressure & accuracy.

Here is a simple trick I used in the old days.....

a) take a fired case and dent one side on your bench to create neck tension
b) take a black sharpie and completly cover the bearing surafce of a bullet,
c) once the ink is dry, insert the bullet into the neck
d) put this into the chamber and close the bolt
e) open bolt, extract case....sometimes the bullet will want to stick in the rifling so insert a cleaning rod and gently push it out.
f) re-assemble the bullet into the case to the line on the bullet and measure it.

This precedure is in the first few pages of every loading manual I have ever seen, I'm sure you could find a ton if stuff on the Google.
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