Retumbo pressure in the cold

[Chandalar]

Today I experienced a bit of a pressure spike in a 338 Lapua. My initial accuracy load was 92 gr. of Retumbo, 285 Hornady's at 32degF. Everything was done the same regarding reloading for both sessions. Today in Fairbanks it was 0 to -5 and I have been shooting these test rounds at 340 yards. in November when the first test was done it had 13 1/2" of drop @340 yards from a 100 yard zero again at 32F. Today at 0-ish my group was at 12 1/2 and there was slight bolt lift pressure. I did not allow the rounds to sit in the fired chamber and "warm up",,, I closed the bolt once I was on target ready to fire. Has anyone else experience pressure in Retumbo at colder temperatures?

 

[Greyfox]

I have personally not experienced it, but if you search this site there are shooters that have experienced increased velocity/pressure with Retumbo when subjected to low temperature.

 

[ShtrRdy]

This thread has been talking about this sort of behavior:

http://www.longrangehunting.com/forums/f28/reumbo-pressure-spike-below-freezing-179248/

 

[tbrice23]

Has anyone else experience pressure in Retumbo at colder temperatures?

Yes, that's my post linked in the above post. Phorwath has a similar experience linked in the last post of the thread.