signs of pressure

[retiredcpo]

just fyi
I have been shooting 64.5 gr of 4831 under 168 gr bergers
for about three months now with no problems no hint of pressure signs
but the temp has never got above 60 and was cloudy most of the time
today was sunny up around 70
and had Major pressure signs bolt extremly hard to lift primmer flat
So ill be backing hte load down to 63 gr to where i started.

 

[Pdvdh]

Which caliber and cartridge? IMR or Hodgdon 4831 powder?

 

[retiredcpo]

opps sorry
7mm rem mag
hodgen powder 4831sc
in a new remington sendero

 

[retiredcpo]

opps sorry
7mm rem mag in a new sendero
using winchester brass and primers

 

[bigngreen]

Same powder lot ? Seems a little excessive over a 10 degree temp movement for a Hodgdon extreme powder.
I use some of the other powders that they have listed as the Extreme powders and I can go from below 0 to 80 degrees with a maxxed out load with no problems at all.

 

[jimbires]

I've also had pretty good luck with the extreme powders being stable . it seems like 90* F is where sensitivity starts to happen .
was your ammo setting in direct sun ? or getting baked in the car ? if so this could be your problem . try keeping your ammo in the shade .

 

[Michael Eichele]

Sounds like it could be 1 of 2 things.

1: A different lot of powder.

2: A slightly worn (erroded) throat. This will cause friction on the bullet driving up the pressure.

 

[J E Custom]

just fyi
I have been shooting 64.5 gr of 4831 under 168 gr bergers
for about three months now with no problems no hint of pressure signs
but the temp has never got above 60 and was cloudy most of the time
today was sunny up around 70
and had Major pressure signs bolt extremly hard to lift primmer flat
So ill be backing hte load down to 63 gr to where i started.

The WW 2 H4831 was my favorite in a 7 rem mag with 67.5 grains behind a 168 SMK.

The newer H 4831 had to be reduced to 65.5 grains and stilled matched my velocity.

When I switched to H4831sc I had to reduce it even more to keep the pressure with
in limits.

64.5 is still a hot load and will cause problems if it is left in the sun or a hot car.

If you are seating close to the lands this could cause pressure to be on the high side.

J E CUSTOM

 

[retiredcpo]

the rounds where in direct sun light on the hood of the truck
most of the previous days ahve been cooler and overcast.
cant imange it would be a throat problem the gun is 4 months old.
taking tnhe gun back in to my smith just to have him look it over before we shoot again

 

[Pdvdh]

the rounds where in direct sun light on the hood of the truck

Ouch! If that hood is painted anything but white, I would guess the cartridges may have warmed up a fair amount.

 

[retiredcpo]

the truck is silver and we use a grey blanket of the hood
Now im not sure backing back down to 63 gr will be enough
according to berger the load range is 61 to 64.5 so 63 is in the middle.
also im 20 thou off the lands