A starting COL for a Weatherby 338-378

[OU812]

I'm a reloading rookie with a COL question. How does one determine a good starting point for the COL. I'm using Nosler 250 grain partitions but don't know at what depth to seat them. Retumbo powder states a COL of 3.660, I've seen RL-25 at 3.760. With the Weatherby freebore there is no way I can come close to the lands (W/O being a single shot) so do I seat the bullets as long as possible while still fitting well in the mag box and chamber or do I follow the powder companies listed COL?

If a load is not working well at what point do you try to determine if it's the COL rather than the powder or bullet? I'm sure I'm making more out of the COL thing than needs to be but I had a question so I had to ask.

Does any one know why Nosler does not list a COL in the reloading manual? It would be a nice thing to see when your using Noler bullets and thier manual.

Bill

 

[JD338]

OU812,

The Wby's have a lot of free bore so you won't be able to get close to the lands unless you load as a single shot. I have a 338 RUM and face the same issues as you.
Load your COL to the length of the magazine.
Also use the Federal GM215M gold match primers.

JD338

 

[OU812]

JD338,

That is what I have done so far. The max COL is listed as 3.763 and I can fit 3.760 in the mag box and chamber just fine and I'm with ya on the primers. I was wanting to try more RL-25 but I have heard it does not like temp varying temps. Retumbo seemed like a good choice for elk hunting but they have the COL listed at 3.660. that may be the seating depth to get the vel they have listed.

 

[JD338]

I don't think you will have any problems. Just watch for pressure signs.
Any changes, if any, in velocity would be small. You have a real powerhouse caliber and you will get pleanty of velocity.
Focus on accuracy.
I use RL25 in my 338 RUM with the 250 gr PT and the best 4 shot group is .490". I am 1 gr below Noslers listed MAX but I am ok with that, its the accuracy that I like. There is more than enough speed and energy to take on any game on the globe!

JD338