300 Win Mag Reloading

[mitch308]

I've just started reloading for my new 300 win mag (savage BA110) , I loaded up 50 new Norma cases with 208grn Hornady ELD to the 3.340 COAL stated in the manual and fired them off (not very good grouping), I've since measured the chamber using the hornady OAL tool and the distance to the lands will give an OAL of 3.630 (.29 longer), also when I measured the shoulder of the fired cases compared to the new cases the measurement to the shoulder is now .017 longer than the non fired case, these measurements seem extreme to me. is anyone experienced in loading this caliber, I could do with some advice. 

[onehole]

Not experienced with the calibre so have no knowledge of freebores that may exist but for the second part of your ask considering shoulder movement then this could well be an acceptable amount of initial growth and good reason to only use a case that has been threaded after fireforming in your rifle and not an of the shelf "modified case" for obtaining touching lands measurements ,,,,if that was the method used of course.

[Andrew]

There is nothing wrong with your load (generally speaking) other than you used new Norma cases. New UPB cases will generally head space on the belt. On the next loading, size them to headspace on the shoulder. This is the way the US Army rifle team produced their handloads for the 300WM.

Seating to Hornady's recommended length is fine and your accuracy will be much improved  -provided the load is well balanced to begin with. I will be loading some of the new Nosler 210 grain RDF's this week to test in my 300WM and will seat them to Nosler's recommended OAL.  Hopefully I will be able to get out to shoot them them at extended ranges shortly thereafter.~Andrew

[furrybean]

The 210 rdf looks like an interesting bullet. How has it been performing?

[gyr]

I have my 300wm loaded to 3,618 COL with the 208 eld. This is from base of case to tip of the bullet, but I normally use a bullet comparator to measure from case base to ogive+ the comparator.

That is about 0,04 in. off the lands, and shoot well.

 

[Andrew]

On 10/13/2018 at 3:30 AM, furrybean said:

The 210 rdf looks like an interesting bullet. How has it been performing?

It is a very accurate bullet but I have yet to take it to any serious distance. My initial loads of RL22 were too anemic and then I got distracted and the project got shelved til after hunting season~Andrew.

[Hobbit]

I have just started reloading 300 win mag - I have a custom Bartlein 30' heavy barrel fitted to my AI AXMC

The distance to lands is quite long deliberately to accommodate the newer high BC bullets

I load a hornady ELD-M 225 gr to an dal of 3.73 which is still 30 thou off the lands

I am using N165 to protect the barrel but 72.3gr gives me a sedate 2720 fps (note the extra length to lands increases available space in case and reduces pressure - as ever - you work up your own loads) but the BC deals with the wind

as a side note I am using Peterson brass which I sorted but in truth was at least as uniform as my Lapua in other calibers - really good stuff, out of production at the moment but I added 200 pieces to my 100 last week from Dauntsey

I have Redding competition sets but actually now use a lee collet die on the neck with threading body die because I get less run out than with the much more expensive competition bushing neck die from Redding

I also noticed 10 thou of growth in the case on first firing and will headspace from neck from now on - by setting the should back by 3 thou or so - I am not an expert but this is my experience