Help with .300wm Load

[spladi]

I am trying to develop a load for a .300wm Christensen Arms Mesa Rifle and can't get it to shoot with a sub 2moa.

This is my current proponents:
205 Berger elite hunters
H4831
ADG brass never fired
Expander mandrel, the pressed for consistent neck tension
Seating depth .080 off the lands (tried right off the lands and same result)
Federal 215M primers

Powder charges:
71.8
72.0
72.2
72.4
72.6

All of them are garbage with random fliers. I've never had this big of an issue with a lid development. We have checked the scope mount and rings. I'm going to try a load I made for another rifle later to see if it does any better.

Did you break in the barrel, to the point of no copper residue on a patch after Butches, Shooters Choice or some other copper removing solvent sat in the bore for about 10 minutes? My last new barrel made a believer out of me for the need to break in
a new barrel. Try H1000 if you have any.

 

[vancewalker007]

I am trying to develop a load for a .300wm Christensen Arms Mesa Rifle and can't get it to shoot with a sub 2moa.

This is my current proponents:
205 Berger elite hunters
H4831
ADG brass never fired
Expander mandrel, the pressed for consistent neck tension
Seating depth .080 off the lands (tried right off the lands and same result)
Federal 215M primers

Powder charges:
71.8
72.0
72.2
72.4
72.6

All of them are garbage with random fliers. I've never had this big of an issue with a lid development. We have checked the scope mount and rings. I'm going to try a load I made for another rifle later to see if it does any better.

First, what does it do with some premium factory loads? If it shoots terrible and inconsistent with factory loads then it may be a mechanical issue.

Second, I've found finding a stable powder load first, before messing with seating depth group tests leads to the fastest result. You are moving your pressure all over without knowing what it's doing. You might be right on some jump points. I read in the posts where someone got you straight on your neck sizing, so that's set.

Third, that bullet powder combo you have may never shoot no matter what you do. It's hard these days with the shortages to try lots of combos. The medium speed powders like H1000, N565, RL26, IMR7977 seem to gives consistently good results. The slower powders like IMR8133, N568, N570, or Retumbo might work great as well. They usually require a drop tube for filling cases and compressed loads to get decent velocities.

 

[robert rex]

300 win mag, 180 Hammer Hunter, .030 off of jam, 71g H4831sc, Lapua brass, Federal Large Rifle Magnum primers seated .003 deep. Five shot group.

 

[BNash715]

Considering supplies are limited and the 205s might be all you have, play with the bullet seating some more. My 300wm tightened up at .020 jump using Bergers.

 

[Teri Anne]

I am trying to develop a load for a .300wm Christensen Arms Mesa Rifle and can't get it to shoot with a sub 2moa.

This is my current proponents:
205 Berger elite hunters
H4831
ADG brass never fired
Expander mandrel, the pressed for consistent neck tension
Seating depth .080 off the lands (tried right off the lands and same result)
Federal 215M primers

Powder charges:
71.8
72.0
72.2
72.4
72.6

All of them are garbage with random fliers. I've never had this big of an issue with a lid development. We have checked the scope mount and rings. I'm going to try a load I made for another rifle later to see if it does any better.

I had similar issues with the Burger Elite bullets with the 170 gr .270 and 180 gr 30 WM. the .270 would not shoot a 4 inch group the 300WM around 3 inches. I gave up and went back to Nosler, Hornady and Sierra and haven't had a problem since. Some rifles just don't like some bullets.

 

[chav0_12]

I have a buddy shooting the same rifle, same bullets using Magpro and getting good results. I think I it's 74.5gr using CCI mag primers, and I'm not sure about the length but he's using Hornady brass and some Winchester too.

 

[Dan swainston]

Bergers can be temperamental with seating depths. Check the lans. Just worked on a christen arm rifle an it had two lans were cut all into the throat. It will throw your bullets. You may have to re bed the barrel that helps.
Went through 4 powders and two bullets til I found one that works.

 

[carl.gotwald]

76.0 4831 SC WITH A 180 NOSLER CT UNDER 1 MOA AVERAGE

 

[mdmiller]

72 @ IMR4350, 180 corelock, 1-10