Home Forums Reloading Big Game Rifles Seating Depth Question in .308

Hey guys, wanted to run something by you, sort of a sanity double-check. I am switching bullets for my Savage Lightweight .308; I'd been loading and shooting the Barnes 168 gr TTSX, for which I'd established a good seating depth/COAL using the Stoney Point bullet comparator tool (measuring case head to ogive). I am now going to the Barnes 150 gr TTSX, which is a fair bit shorter bullet than the 168. So I have a couple of questions related to this, sort of conceptual but also, applicable.

First, is it reasonable to expect that the 150 bullet would perform similarly (as far as accuracy) if it is seated such that the COAL is the same as how I had loaded the 168? It would therefore be the same distance from the lands which I presume is the biggest factor in performance. My other thought was that in that scenario (same COAL) the shorter bullet would have more empty space/volume in the case so then would the combustion and other physics result in different performance?

Second, to produce the same COAL in the 150, I would just use the existing setting in the seating die that I used for the 168, correct?

Maybe I'm overthinking this, I just want to get to a load I'll be happy with minimal time and component usage. Anyway, thanks in advance!

That would depend on how closely their ogives match. Why not just back off a bit and adjust to suit?

Yeah, load up some using the same seating die setting, and see how they shoot. Chances are that the differences in ogive dimensions are not enough to matter. If they don't shoot as well as you'd like, adjust the die to seat deeper.

Why not just find the lands with that bullet, so he knows for sure. Then it's not a guessing game. He can try different seating depths because what one bullet likes, the other may not. Some of you guys not willing to start at the start and trying to take shortcuts are ridiculous. Quit being lazy. This schidt isn't hard to do..

Do you say that to everybody shooting factory ammo? Seating a bullet to a depth that allows the firearm to function appropriately IS the start.

We don't know that he found the lands with the first bullet, unless I missed that somewhere.

I assume a .308 Savage lightweight is a hunting rifle? Do you really need more accuracy than Federal Gold Medal Match? Maybe you could get a Fed GMM, or Black Hills, round or two, use it to set your seating die and soldier on. If your group at the bench opened up a .100 thou...would you really care or know out hunting? Unless...you enjoy gilding the lily.

That doesn't relate very well to a 150 grain Barnes.

Crusader, I load the Barnes TTSX in 130 grain in a Model 70.....Barnes site says 2.735 for the 130 and 150 COAL in the TTSX. I load at 2.750 and get 1/2 MOA using TAC power. I would try that depth and see how it groups.....you know Barnes like a nice jump.

Yeah, you're right, how could i have missed that after the hell I went through when the Emperors that rule here in the land of Fruits and Nuts decreed copper bullets or death. Switching over 8 cartridges to copper was an exercise designed to make old men weep. When you add the variables of throating dimensions, increased cost and inventory of the copper/platinum alloy (I'm sure they have platinum judging by the price) bullets, choked supply lines, powder shortages etc etc it became the stuff of nightmares. The constant drumbeat of, "Oh, they like a jump of .xxx thousandths" did not solve many problems in my little world. My best copper bullet tip is, carry a couple in your pocket to show the game warden in case he's interested. Sierra Pro Hunters got some copper around 'em, that's good enough for me.

All the people I have ever seen who had problems with Barnes had a shortage of RTFI.

Start at 40 thou off lands. Problem ? Seat deeper. It always works.

I run 2.760" with 150 TTSX

The lands are usually further than what will run in a repeater anyway. Additionally, the lands are a moving target. Don't concern yourself with lands other than ensuring the bullet stays out of them on a hunting rifle.

Each bullet should be worked up independently without regard for how other bullets prefer to be. There will be nodes along the way, load as long into a node as you can so that as the throat erodes, you can stay in it.

I was following Barnes seating depth instructions off the web page, says to start .050" off, then seat deeper in .025" increments until best group is achieved. 4 of the 8 chamberings worked great, 4 remain only adequate, and the problem child is the 7x57...maddening lack of accuracy from a rifle of known accuracy. One thing that stands out, the three of the four that shoot well were born in the USA. The 4 that are disappointing are all born in Europe...does CIP have different chamber/throat prints?...or a simple coincidence? I used to enjoy a reloading challenge...not so much anymore.