.338 RUM seating depth

[USCGLongBow]

I'm not new to reloading, but this caught me a little off guard and I was hoping you guys could give me some insight. The round on the left is my tried 200gr Bal Silvertip loaded to just engage the lands as the bolt closes, and the round on the right is a fired case with a 265LRX seated by running the bolt forward in the gun. Both rounds will allow the bolt to close without moving or scarring the bullet. Is this usual with the ogive difference between a BT and TSX bullet?

 

[300 ultra]

Do you have a bullet comparator for your calipers to measure? That looks like a dramatic difference between the 2 by the picture.

 

[USCGLongBow]

I don't right now, I might need to run and grab one. I agree, it looks like a big difference and the ogives don't even seem to line up. But I have always used the rifles to determine the necessary seating depth, and this is the first time I have seen this type of difference.

 

[Speedygoss]

I'm guessing when you get a bullet comparator you will find that the silver tips are not to the lands as you thought. My 265 LRX and 250 Bergers look allot like the 265 LRX in your photo for length.

Let us know what you find out.
Thanks.

 

[Engineering101]

I suspect Speedygoss had it right. The short round isn't near the rifling. Rather than buying any tool just take a beat up case ready to load a bullet, split the neck with a hacksaw so you can put it in your rifle with a bullet just seated and use the rifle to seat the bullet as you did with the 265 LRX round. You will need to file the cut to be smooth and adjust the tension so the bullet doesn't get stuck in the rifling. You should be able to move the bullet in or out of the case by hand but just barely. Seat the bullet several times and verify that you get the same reading every time within 0.002" or so. I have one of those cases for everything I load. That is how I determine max load length for every bullet and I also use it to setup my bullet seater.

 

[USCGLongBow]

I suspect Speedygoss had it right. The short round isn't near the rifling. Rather than buying any tool just take a beat up case ready to load a bullet, split the neck with a hacksaw so you can put it in your rifle with a bullet just seated and use the rifle to seat the bullet as you did with the 265 LRX round. You will need to file the cut to be smooth and adjust the tension so the bullet doesn't get stuck in the rifling. You should be able to move the bullet in or out of the case by hand but just barely. Seat the bullet several times and verify that you get the same reading every time within 0.002" or so. I have one of those cases for everything I load. That is how I determine max load length for every bullet and I also use it to setup my bullet seater.

I did this with the Silvertip already, that is how I determined seating depth for loading. My gun has an unusually short throat and the bullet will catch in the rifling if not seated that deeply. I actually didn't believe my original readings, and left the bullet out .005" with my first box. But after not being able to close the bolt on half the rounds, and having two bullets stick in the rifling and pull out of the casing, I settled on this seating depth for safety.

 

[USCGLongBow]

I apologize, and am also a little more confused. I tried the silvertips in a fired case again, and the new length is MUCH closer to that of the LRX. So I was seating them too deeply, but the issues I had with them catching on the rifling and marring the bullet was two months ago after having not fired the gun in two years. And I'm a little curious to know what caused the false readings I was getting. Thanks for the help guys, if I ever get to the bottom of what happened I will post the results.