I found this information from Dr. Drew posts.
From the German proof house:
minimal wall thickness at end of chamber, regardless of length, for 12, 16 & 20 gauge guns should be 2.3mm (.0906") for 'ordinary good steel' or 2.1mm (.0827") if a 'Special Steel' was used. For the 24 & 28 gauges, due to their higher pressures, 2.4mm (.0945") was recommended.
Minimal wall of .6mm (.0236") was recommended in the "forward third" of the barrel.
I measured my O frame Parker 20ga and it measured .096 in front of the chamber and my Fox CE 20ga .098.
All my Parkers are Damascus 20ga to 8ga. 99% of my clay target shooting is not for score so in 12 ga I shoot 3/4oz at 1200fps Clay Dot powder @5600psi. If I miss some clay targets due to the reduced load, I could give a dam, because the reduced stress on the gun is more important to me than than my score. But then it comes to live birds I use the max load for which the gun was originally built.
|
Threaded Mode