N550 with 210 grain Matrix/Berger for 308 Win

[Bear_Blade]

Hey guys, been using reloader 17, with Lapua brass, 210 primers, with 210 gr Matrix bullets. Was doing quite well, with velocities of 2620 fps/average.

On a warm day a couple weeks ago, I had 2 primers blow out of their pockets. I was warned about RL17 being temperature sensitive, and can find no other explanation for the primers blowing out.

I want to run with some VV N550, and am looking for a bottom benchmark to safely start from, as well as an upper "Watch it dumbass" load, or a "I have used x.x grains and saw pressure signs" so I have a preconceived max charge.

I am aware your load/gun/set up isn't mine, and will proceed with caution, but I am unable to find reliable data. I have found some loadings, but I think were being "pushed" hot. I really need to figure where to begin.

 

[Boomer]

The Matrix .308/210 VLD is very similar to the Berger. Berger's starting load is 39.0 gr of N-550. A word to the wise, if you're not familiar with N-550, the pressure signs can be subtle, then come up and bite you if you miss them, as could be the case when shooting in bright sunlight. As soon as you see the chamfer between the primer and the primer pocket disappear, you've gone too far. Don't count on a sticky bolt being your final warning. If you work up your load over a chronograph, and your chamber is within SAAMI specifications, 2450 fps from a 24" barrel should be your red flag velocity.

My chamber was cut so that these bullets could be seated long in the case without entering the powder capacity of the cartridge. My normal procedure for determining a maximum load, which was to work up in 1 gr increments until I observed a sticky bolt, proved to be inappropriate with this powder. My purpose was to ensure that when I began to work up to the accuracy potential, that I would be adjusting the powder weight away from the highest pressure rather than towards it. Had it been for a hunting load, I would have simply used a full grain below the sticky bolt load as my working load to ensure that component tolerances wouldn't get me in trouble. I'm not trying to scare you off N-550 but you might as well learn from my misadventure.

The results of 1 gr increment increases. Note that the chamfer between the primer and the primer pocket is gone, the subsequent increment of powder was a problem.


I continue to use N550 and Matrix 210 gr VLDs in my rifle, and it has since proven to be a delightful combination at ranges beyond a half mile.

 

[sundance1972]

Just wondering if Varget is a good powder for the 210's? Marshall gave me about 400 of them, as well as some 185's and 168's. Somewhat new to loading for the 308, but the 168's are quite impressive so far.
Will probably try the 185's and 210's in my 300 Win as well.

 

[Republic of Alberta]

Bear Blade, I have worked loads up with R17 as well. I got very high velocity's with 208g bullets but knew the pressure was sky high even though I was not seeing any pressure signs. I just had the "feeling" with this powder the first sign I was going to see would be gas in my face so I went back to 2400fps and stayed there.

Since then I was talking to a guy that had the same thing happen as you with R17 and the 208g Amx in 308 with Lapua brass. He claimed to have shot lots of rounds then one day blew a primer, his loads were also up in the velocity range you were seeing. Stared to research it on the web and found others that had the same thing happen.

R17 is not a magic powder, the reloading manuals do show top velocity's with it in some instances but it only beats out other powders by a small amount.