6.5 PRC

That’s good info! That’s good velocity too. Is that on a chrono? Berger data suggest 2644fps at 54.5
That load data from Berger has changed a few times - I've seen threads (wanna say it was on snipershide or Rokslide) where members posted emails from Berger and the data was definitely different.

Your rifle is telling you that you were too hot. Back it down and find another node.
Do you have the latest load data? If so would you mind either posting it here or sending it to me?
 
I think 58 gr of H1000 is too much powder for 156 gr Bergers regardless of the temperature.
I am loading 156 Berger's over 56 gr of H1000, 2.280 CBTO with velocity 2950 and .3 moa with no problems in Texas. This is the sweet spot for my 6.5 PRC , Zermatt TL3 action and 26" Proof CF barrel. Any loads hotter than this (and I stopped at 56.8) showed pressure and groups expanded to 2" @ 200yds. Back off the powder in increments until find a sweet spot with good MOA and velocity.
 
That’s good info! That’s good velocity too. Is that on a chrono? Berger data suggest 2644fps at 54.5
That's an average through my chronograph. I don't have the data in front of me, but it was pretty consistent. Less than 25 fps variation if I recall correctly. I live at 4300 feet and the temp was about 70 degrees when I shot to get that data. Seems to be pretty close, but not perfect on my ballistic app. I shot it at 411, 522, 650 and 833 yards this morning and it was consistent and accurate. (I know, odd yardages, but that's how my range sets up due to topography.)

You'll get it figured out. Best of luck. The guys on this site have excellent insight and experience.
 
I think 58 gr of H1000 is too much powder for 156 gr Bergers regardless of the temperature.
I am loading 156 Berger's over 56 gr of H1000, 2.280 CBTO with velocity 2950 and .3 moa with no problems in Texas. This is the sweet spot for my 6.5 PRC , Zermatt TL3 action and 26" Proof CF barrel. Any loads hotter than this (and I stopped at 56.8) showed pressure and groups expanded to 2" @ 200yds. Back off the powder in increments until find a sweet spot with good MOA and velocity.
I use 56.0 grs. RL26. If it's warm out I get sticky bolt. Same thing happens with 80.0 grs RL26 with 180-182 Hammer when gets hot but shoots great. I tried 90.0 grs RL26 WITH 182 Hammer in 300 RUM a week ago. It was about 75 degrees. Not very warm. Had no pressure signs and shot great. Going to load hotter. I'll bet if it's a warm day I'll get pressure signs quickly .
 
I have burned many 8lb jugs of H1000 in 3 different .300 Win Mag rifles and multiple barrels over the last 20 years or so and have found it to be very temp stable. If your load is showing high pressure, I'd say it probably has more to do with just too much powder, and less to do with the temperature.
I'm going to try some loads with H1000 also after today. I have quite a bit of it and Retumbo. May try Retumbo also. Have to sight in today .
 
If you need a mallet to open the bolt, then your loads are too hot. You are pushing the brass to its limit, in my cautious opinion. 95 degrees is warm but not as warm as carts left in the sun.
Have you stretched the brass just above the extractor groove? I wouldn't use that brass again.
 
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