cold weather preasures

[harfman99]

Hello everyone.

I was out doing some load workup with my 7 ultra today and had some problems with over preasuring cases. The temp out today was a balmy -5 deg F. The loads was 91-93 grns of T870 in half grn increments,fed 215's, berger and jlk 180's. The avening did not yield very good results. I started out with the bergers and doing five rounds of microlon with the sighters. The first round sounded and felt really good untill i ejected the spent case. I did not expect to see what i did. There was a nice shiny extrusion where the brass flowed into the extractor. Being that the bolt didn't lift heavy I fired another four and still showing preasures. the rifle being sighted in i moved back to 200yrds to see if either bullet was going to work at these preasures. I shot the jlks first @ 91grns and also still showing preasures. Next were the bergers with the same charge. By this time I was getting cold and put five down fairly quickly and noticed as the barrel warmed the preasure signs went away. The barrel is a Shilen select match in a 7H taper @31".

The Question is has anyone had this same problem. From the data that i have found 91 grns should have been a good starting point.

Any info would be greatly appreciated.

Thanks
Chris