New 300 Win Mag with 215 Bergers

[Kevin87]

Yep. Started at 73.0 and worked up in 1/2 gr increments. Perfect barrel break in.

 

[trailrider121]

I just built a 300wm with a 26" 9.4 twist Proof barrel and had it chambered with the Rhian Mantha reamer designed to shoot 215 Bergers. I wanted to run VV N570 powder as it has the best velocity I have found for the 215. It meters like crap because the grains are huge but I am getting right at 3100 FPS with the 215. I for sure recommend starting low and working to a max load. If you cant find the VV N570, then the H1000 is the next go to powder with a slight velocity loss of 100-150 FPS.

I have the same reamer using a Brux 9 twist 28" #4 contour. Using Gunwerks 300 wm brass, 215's, 77.7grs H1000, and getting 3045 fps. This 300 wm absolutely hammers.

 

[Okanogan]

Question, for all you gents running the 215 Burger LOL is your throat standard or SAAMI ? or did you opt for a bit longer throat to run these bullets. I get the feel that the benefits are multiplied if you "long throat" your 300 a bit??

I'm am running a long throat in both my 300WMs. They both have what GAP calls their NSW reamer. One rifle has a AICS detachable mag that manages to let me squeeze out 3.620 COAL with the 215s which puts me about 0.075" off the lands. The other rifle isn't limited by a detachable magazine and I'm running 0.035" off the lands. I think I saw in another post that you are mag limited for COAL so that might make the 215 and similar bullets less attractive. Or, you may get lucky and just be able to back off powder charges and get them to shoot well, albeit a little slower.

 

[Double Dropper]

yup the box has me limited and the 3.510 is max. Still running some decent loads with the 212ELD-X (215 Bergers are not in yet) 74.5 grains of RL-25, 77 grains of 8133 and working on a load with H1000 so the SAAMI throat has not become an issue yet. The ADG fresh brass has been a limiting factor but I keep hearing not to worry about the reduced capacity. Still basically fire forming the first 100 cases with test loads.

 

[brentc]

Worked up a load yesterday--ended up at 77.5g H1000, .020 off the lands, CCI 250 primers. Average was 2953 fps with no pressure signs. Very happy with the Ridgeline so far. Thanks for all the input!View attachment 151339

That was exactly my load in my Ridgeline before I had to reduce with the new powder lot.

 

[FURMAN]

Worked up a load yesterday--ended up at 77.5g H1000, .020 off the lands, CCI 250 primers. Average was 2953 fps with no pressure signs. Very happy with the Ridgeline so far. Thanks for all the input!View attachment 151339

That should work!

 

[Russ661]

Wow, I must just have a slow barrel. 300WM, 24 inch 1:10 twist. With 215 Burger hybrids over 70 grains of H1000 in twice fired ADG brass I'm already seeing flattened primers and only 2692 FPS. At .010 off the lands it shoots .6 MOA. Thoughts?

 

[Wolf76]

Wow, I must just have a slow barrel. 300WM, 24 inch 1:10 twist. With 215 Burger hybrids over 70 grains of H1000 in twice fired ADG brass I'm already seeing flattened primers and only 2692 FPS. At .010 off the lands it shoots .6 MOA. Thoughts?

7 grains of powder and a shorter barrel will account for your velocity. You found the low node.

 

[FURMAN]

Wow, I must just have a slow barrel. 300WM, 24 inch 1:10 twist. With 215 Burger hybrids over 70 grains of H1000 in twice fired ADG brass I'm already seeing flattened primers and only 2692 FPS. At .010 off the lands it shoots .6 MOA. Thoughts?


What rifle and what are you loading your OAL to?

 

[Okanogan]

Wow, I must just have a slow barrel. 300WM, 24 inch 1:10 twist. With 215 Burger hybrids over 70 grains of H1000 in twice fired ADG brass I'm already seeing flattened primers and only 2692 FPS. At .010 off the lands it shoots .6 MOA. Thoughts?

I doubt it is the ADG brass. I can get everything out of it I get with Norma, but with less powder. I'm shooting 24 & 25" barrels but definitely get more than 2700 before I start to show pressure signs and I am running a 1:9 twist. (I have never tried as low as 70 gr but that would certainly account for the lower fps but not the pressure signs) If you're not loading short COAL (i.e., some near SAMMI) then I would think it is your barrel or the particular batch of H1000.

 

[Russ661]

Wow, I must just have a slow barrel. 300WM, 24 inch 1:10 twist. With 215 Burger hybrids over 70 grains of H1000 in twice fired ADG brass I'm already seeing flattened primers and only 2692 FPS. At .010 off the lands it shoots .6 MOA. Thoughts?

What rifle and what are you loading your OAL to?

Rifle is a trued Remington 700 with a Muller barrel. Best accuracy comes with the bullets seated .010 off the lands for a OAL of 3.656; magazine length is 3.725.