Decided to try a short on-line article. There are few things more frustrating at a match than having a hull stick or jam in your shotgun. Hopefully, here are a few ideas to help avoid that from happening. Shotgun ammo needs to be gauged before shooting it at a match. Even brand new Winchester AA feathelites (LowNoise, LowRecoil) have sporatic problems. I have found many individual shells in a case of shells that had slight bulges in the side walls and were difficult to chamber and would not shuck. You want to find these shells before a match, not during a match. I shoot doubles, 87s and just recently tried a couple of 97s I have had for over 20 years but not shot. I also shoot trap several times a week. At present I have three gauges. What is truly amazing is that ammo that fits into one of these gauges may not fit into the other gauges. I do cross checks occassionally but use a specific gauge for a specific gun type. Here is a shot of the gauges.
My favorite 97 is a late E series solid frame. At several matches I had jams and malfunctions I could not intially explain. This was with new and reloaded ammo. I finally completely disassembled the gun so I could get an inside micrometer into the chamber. Chambers have minimum and maximum dimensions. When reamers are new they are close to the maximum dimension. As they wear they get smaller and then need to be replaced. My 97 is dead on the absolute minimum chamber dimension. Must have been the last gun chambered before they threw away that reamer. So a maximum round in my minimum chamber and things got sticky or jammed when the gun was fired. For the 97 I use a case gauge that is made to measure a minimum spec chamber.
Rounds that are above minimum chamber spec hang on the edge of the gauge.
I use a collet style sizer on my 97 ammo to make sure the ammo head diameter is BELOW the maximum spec for factory ammo. This ensures the shell will drop freely into the gauge and, more importantly, my 97. If loaded rounds stick in the gauge and cannot be corrected by a second trip through the sizer they go into the goof around practice box.
For trap loads I have a gauge that was cut with an actual chamber reamer. If the rounds drop into the gauge they will fit any of my trap guns. If they are a slightly tight fit it makes no difference as you can manually push the shell into the chamber and the ejector will kick it out when it is fired.
Ammo for the double barrel needs to be the most precise. The rim has to pass the gauge test but more importantly the crimp area has to gauge properly or it might not shuck after it is fired. Most problems with shucking are not caused by the case head expanding as SASS ammo is loaded light so that is not generally an issue. Most problems are caused by the crimp unfolding when fired and not shrinking back enough to be released from the chamber mouth. The more often a shell is reloaded the more apt the case mouth is to get a slight mushroom shape. The next gauge is designed to help fix that problem.
You are checking for two things with this gauge. First if the rim is sticking it won't seat in the gauge.
The bigger problem on most shells is, however, the crimp area and it is the more likely culprit in keeping the round from dropping into the gauge. To fix the problem you stick the shell in the other end of the gauge and give it a couple of twists or wiggles and then try it again in the other end.
IF you can drop the shell into the gauge and it drops in freely up to the rim AND drops out of the gauge when you turn it over it will most likely work fine in your double. If the rounds do not drop in and dump out freely put them in your junk box practice rounds. Trying to wring every reload out of a five cent shotgun hull is a false economy, especially if it sticks on you in a match. When the plastic gets pin holes the crimp will tend to loosen after the shell is reloaded. Even using this gauge the case mouths can open a bit if they aren't fired within a reasonable time of gauging the shell. I do a final gauge of my shotgun ammo at my cart when I am replacing shells fired during that stage.