I worked up a new load for my 6.5x55 with H4831s, Berger 140gr Hybrids and Hornady 5x fired brass last week at the range. Shooting in the shade and 65 Degree weather, I went from 45.0 grains up to 51.1 with no pressure signs. I knew 51.2 was a hot but fast/accurate load from another reloader, so I intentionally stayed just below it and didn't exceed it. OCW node and good accuracy was obtained near 50.9 gr, and 0.025" jump, so I went with that.
So yesterday I get out to the mountains with 50 of my new load. It is probably 60 degrees, and no wind... absolutely beautiful. The two hours of shooting go great, I make some really fun shots out to 600 yds and then go to reset and move targets. When I come back to fire another 10-15 rounds, it has warmed up some, probably closer to 80 degrees in the noon sun. About 5 rounds in to my second go, I immediately noticed that one of the shots had significantly more recoil, and even sounded a bit louder. To this point, I had never actually seen "sticky bolt lift", "difficult extraction" or "ejector swipe marks". But right away, I saw all three (Which was neat to see, but also scary to see all three all of a sudden with no prior indications). I (carefully) fired a few more rounds to try to figure if I had just tricked a charge wrong, or if my load was too hot. The next few rounds had the same behavior, so I called it a day and packed up.
In hindsight, I think that the load is probably OK in cool / cold weather, and when the gun / ammo is not hot. But after sitting in the sun for a few hours, I think the ammo was heated up and the chamber of the rifle was hot as well, which pushed me from a borderline load at good conditions to an unsafe load.
Plan right now is to reduce load to the lower end of the accuracy node I found, probably about 0.3g lower and see if I encounter the pressure signs in the heat again. If so, I will be moving to a lower accuracy node or changing powders. Any thoughts or advice?
Pics show every round I fired yesterday, roughly in order. Rounds with pressure signs are near the unfired rounds.
So yesterday I get out to the mountains with 50 of my new load. It is probably 60 degrees, and no wind... absolutely beautiful. The two hours of shooting go great, I make some really fun shots out to 600 yds and then go to reset and move targets. When I come back to fire another 10-15 rounds, it has warmed up some, probably closer to 80 degrees in the noon sun. About 5 rounds in to my second go, I immediately noticed that one of the shots had significantly more recoil, and even sounded a bit louder. To this point, I had never actually seen "sticky bolt lift", "difficult extraction" or "ejector swipe marks". But right away, I saw all three (Which was neat to see, but also scary to see all three all of a sudden with no prior indications). I (carefully) fired a few more rounds to try to figure if I had just tricked a charge wrong, or if my load was too hot. The next few rounds had the same behavior, so I called it a day and packed up.
In hindsight, I think that the load is probably OK in cool / cold weather, and when the gun / ammo is not hot. But after sitting in the sun for a few hours, I think the ammo was heated up and the chamber of the rifle was hot as well, which pushed me from a borderline load at good conditions to an unsafe load.
Plan right now is to reduce load to the lower end of the accuracy node I found, probably about 0.3g lower and see if I encounter the pressure signs in the heat again. If so, I will be moving to a lower accuracy node or changing powders. Any thoughts or advice?
Pics show every round I fired yesterday, roughly in order. Rounds with pressure signs are near the unfired rounds.
