300 Win Mag COAL question

[sled_mack]

I've just put together a rifle in 300 Win Mag. It has a "RemAge" style barrel nut setup.

I'm using Berger 215 hybrid match bullets. The brass is virgin ABM.

To find the lands, I used the method of closing the bolt on a bullet seated really long, kept seating it a bit deeper, until the bolt falls closed with no resistance. The ejector and firing pin were removed for this.

I got a COAL of 3.669 and a distance to ogive of 2.895 (I realize this is almost useless as no two comparitors are the same).

Book max COAL is listed as 3.34. So I am way over max COAL when I am at the lands. But, the rounds still fit in the magazine (internal box mag). It's close, but they do fit.

As far as I can tell, the bullet is deep enough in the neck of the brass that the boat tail is below the neck/shoulder junction.

I have checked, double checked, tripled checked, and checked the headspace again. It is still good.

Should I be concerned about this? Should I start load development at book max COAL or start at a small jump to the lands? I plan on doing an OCW workup to find powder charge, then check for seating depth - I know Berger has a page on their web site with recommendations for finding the jump with their bullets.

This is my first belted magnum rifle, so I'm being extra cautious here. If this were my 308, I'd start load work at 0.020 off the lands and not look back.

Thanks,
Steve

 

[briang7511]

you should find about .020 to .030 jump will work fine with the 215. my coal is 3.630 with a .020 jump

 

[Okanogan]

I'm using Berger 215s in my 300 WM. I started 0.010 to 0.040" off the lands with only slightly better than 1 MOA groups. I was a little disappointed and decided to try 3.625" COAL (about 0.115 off the lands) so they would run in my ACIS magazines. I figured why not try it if the Applied Ballistics factory ammo was supposed to be 3.60 COAL. My groups tightened up to consistently 1/2 MOA or better. I'm running 2840 fps through a 1:9 Bartlein barrel. If you don't find closer to the lands working well for you, then you might consider backing off further as you look for a load your rifle likes.

 

[sled_mack]

First round of testing today. Started with a .110 jump, a COAL of 3.57. Found a promising node.

Another question - first round I loaded in 0.6 grain steps. How fine of a step should I take for the second round?

For 308 size cases I usually start with 0.3 and move to 0.1 for the second round. That seems like a big jump with this much powder.

Thanks

 

[wapiti16b]

I plan on using the BERGER Hybrids also and the HORNADY 212 ELDX , What jump does the ELDX prefer if anyone knows ?

 

[mdmp5]

Book OAL means absolutely nothing. That length is usually given as the max length you can get away with when using the shortest throat rifles on the market. If you have measured your throat, then you are free to seat all the way to your measured lands. As a reference, my oal for 210 smk is around 3.68 or so.

You don’t need any special considerations for a belted cartridge over a non belt either

 

[Shoots 700's]

i am running my 215's at 3.625 and getting 1/2 moa at 100 yards