I wonder how much impact the actual length of the hull you are shooting has when the shell is longer than the chamber. Certainly it has a bearing, but at what point? I see mention of 2 3/4" shells but I don't know if I have ever measured a 2 3/4" shell. I have measured plenty that were intended for guns with 2 3/4" chambers. I never really paid much attention until the first time I trimmed some 16 gauge Fiocchi GT hulls down to 2 1/2" for a short chambered English gun. Everyone told me I could shoot low pressure shells for 2 3/4" guns but that gun will turn one hundred in just a couple of years and I'd be nervous every time I pulled the trigger. I don't think that would make me shoot my best so I decided I was going to load shorties for it. What I noticed was the little ring of hull that was trimmed off was nowhere near 1/4". The shells ended up measuring 2.6" prior to trimming. Today I measured a few other hulls that I have laying around. The 12 gauge hulls, particularly the Remington and Federal, came close to 2 3/4" but none of the 20 gauge hulls I measured did. Even after I trim 20 gauge hulls back to 2 1/2" they are still longer than the chambers in my old 20 gauge Fox by about 1/8". Here is what I got checking a handful or two of several different hulls:
20 ga AAHS 2.61" - 2.64"
12 ga AAHS 2.68" - 2.70"
16 ga Rem. 2.67" - 2.69"
20 ga Rem. 2.66" - 2.67"
12 ga Rem. 2.72" - 2.74"
20 ga Fed. 2.64" - 2.65"
12 ga Fed. 2.70" - 2.72"
I know this gets off topic but what about the effect of crimp depth? The first time I read how much that can have an effect on pressure I didn't believe it was true. That impact is far greater than what I saw from the Bell or Garwood tests when using hulls 1/4" (or less) longer than the chambers.
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