Been reloading for year and years. Learned something new the other day.... Loading a wildcat... not a big deal anymore but I switched bullets to a heavier one. Powder I was using was on the slightly fast side for the bullets I was using so I switched to a slower powder. Long story short I loaded lots of test loads (like 20) and shot them over chronograph. Bullets were slower than expected pressures low so I kept putting more powder in. Case filled slight compression of powder was second last load. Slightly sticky lift and speed was more than acceptable but weather was warm. Tried the next load. 0.5gr more powder. Small neck case in .22 cal. Powder right to the top. Compress powder with bullet and pull trigger. No smoke, same noise and recoil. Very stiff bolt lift. Case separated and stuck in chamber. Primer pocket and case head .004" oversize. Head stamp on case nearly flat with brass flow into ejector slot. Swelled chamber but I have my eyes and no bolt in my head. Apparently powder burn rates get substantially faster when compressed.... I knew things would change but had NO idea that it would change that fast with such an extreme pressure rise! Measuring case head expansion I knew my brass would hold for 6-10 loads before primer would loosen on the load just .5 gr less powder.
Hope this helps someone someday.... My buddies think I'm a dumb*** and I should have known better many years ago I have never run into this before..
