Craig: as you know that statement was based on a study of 12g shells
https://docs.google.com/document/d/1...A/edit?tab=t.0

We have NO data regarding using long for chamber 16g or 20g shells.

Again, some modern nominally 2 3/4" shells are shorter than 2 3/4". It was recently reported that Aguila 16s were short
https://trueshotammo.com/ammunition/...1-oz-1200-fps/

Are Manufactures supposed to release the pressure for their various loads?
I've been using Fiocchi 12 ga 2 3/4 " 1oz 1250 fps 7.5 shot shells in an $800 Trojan which I found out yesterday, when I got my little feeler gauge, only has 2 1/2" chambers.
I immediately switched to using RST 2 1/2" shells.
The Fiocchi cost $120 a flat
the RST $230 plus shipping.
I can:
Practice with an old Remington 1100 I have, which I would rather not do.
Have the chambers lengthened on the Trojan.
Continue to use the Fiocchi in the 2 1/2" chambers.
Or be distracted by the thought that every time I pull one of the triggers it will cost me a dollar if I switch to the RST, and accept the fact that using the old gun I like will cost me.
Your thoughts please.....

The U.S. makers decline to provide pressure data, and with the exception of Tom Armbrust, those doing ballistic testing won't test factory loads.
Most of the Italian makers do.
B&P Comp One 28 gm is only 6530 psi

IMHO it is likely your 12 g chamber is 2 5/8"
There is an easy way to measure chamber length using a 3" x 5" index card, rolled lengthwise, and slid into the chamber. It will partially unroll and expand to the chamber diameter.
Gently advance the card until it stops at the end of the chamber (where the forcing cone constriction starts), use a pencil to mark the card at the breech end of the barrel, and repeat the steps to see if it always comes to same spot.
Then use a ruler to measure the length marked on the card.
The chamber must be clean, and it works best with a new 3” X 5” card.

Let us know what you find.
If 2 5/8" (and I recognize we're quibbling over 1/8") pick a 1 oz at 1200 fps, shoot and be happy.
It's more difficult with 16g and 20g loads.

Or a 1 1/8 oz., 1145 fps load.

My comment was meant to imply the fact that components aren’t so cheap anymore, not just for 2 1/2” loading.





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Getting closer to figuring this out...
3 X 5 card resulted in more or less the same as the feeler gauge
Pic 1 is a 20 ga sold to me as a 2 1/2 chambered gun
Pic 2 is a 12 ga which I thought was 2 3/4 but probably 2 5/8 the way the markings fall compared to the 20 ga
I checked my 16 ga and the markings fall the same as the 20 ga - so that one must be 2 1/2 and currently cannot find shells for.
Clays ammo has them in a container off the coast of Florida.
My plan is to use the light load 2 3/4 shells in the 12 ga
RST 2 1/2 shells in the 20 ga
And continue searching for the 16 ga 2 1/2 shells.
Would love to find shells for the .410 that was just offered for sale, but that may have to wait a while :)

You can certainly shoot 2 3/4” ammo in a Trojan without lengthening chambers. I’ve been doing it in all of my Trojans since 1961…





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Your picture seems to me to show your chambers are 2 5/8", intended for 2 3/4" ammunition.

If they fit in the hull and allow for a good crimp then more power to you. Speaking for my experiences, using standard wads in my 2 1/2” hulls did not result in good crimps. The majority of my 2 1/2” loading is with 16g hulls. I do load 12g too and use short wads for them too.

Please measure your fired shells. I have found many fired cases in 12 and 20 are short. If the ones you shoot measure to your chamber case closed.