doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 2.5 inch 20 gauge ammo

I called about the Caledonia shells, which are Scottish, by the way, and asked why they are listed on the website as 2 5/8" instead of 2 1/2" and was told they are 2 5/8" ,but they meet the CIP limits for the 2 1/2" ammo standards. This does not make any sense to me as the whole theory of shooting longer shells in shorter chambers is that they have no room to unfold and the shot column has to squeeze past the end of the case to enter the forcing cone, thus raising pressure. Am I missing something here? Any thoughts?

Many 2 1/2" chambers really measure 2 5/8" and are still "in proof". 2 5/8" shells should be fine. How much are the 20 bore Caledonian shells, btw?

He quoted me $7.07 per box and $17 freight per flat from Wis. to S.C. You know, I recently bought a bunch of Winchester 20 ga. shells from Wally world for $5 a box and they shoot damn good for cheap shells. I've used them in sporting clays and the hulls measure 2 5/8" unfurled, so I'm wondering, why not shoot them in this new 20 ga gun with 2.5" chambers, if the case length is the same?

I'm no expert, but I think shells are measured with the mouth open, i.e., without the shell loaded and crimped. The Win shells will likely be higher pressure unless feather lights. What kind of gun are you shooting? BTW, $7.07 is pretty reasonable for an English (scot) shell imho. Like I said earlier, the 12 ga are great shells with high quality shot.

It is an E.J. Churchill Hercules grade with 2.5" chambers, proofed for 7/8 oz. loads, wgt. 5lbs. 6ozs. The length thing still does not make sense to me. If the 2.5" shell is actually 2 5/8"unfolded, why not just shoot any 2 3/4" factory 3/4 or 7/8 oz. load? You are still shooting a long case in a short chamber regardless. In regards to the shells, the freight cost seem to be a large factor in the overall cost. the Caledonia would be almost $9 a box delivered to me.

You can lead a horse to water but it's hard to make him drink. Wally World Win promo loads are high pressure loads meant to function the action of an automatic...a steady diet of those would be very hard on a less than 5 1/2 lb English gun, such as your Churchill. Besides, how much will you shoot a gun that light?? Not much, I'm guessing, so cost of shells is not all that important. I'd get the right shells for the gun. RST shells are great, but even more costly than the Caledonians.

Buzz, I understand that the RST, Polywad, etc. are low pressure, but what I don't understand is why a 2 1/2" shell ain't really a 2 1/2" shell. It defeats the whole purpose of a short chamber when the ammo is not the right length to unfold and be within the chamber proper. That's what this horse is asking.

Note that at least as Early as 1910 W W Greener stated the actual length of the "Nominal" British 2� gun's chamber was from 2 9/16" to 2 5/8".
As stated earlier most "2�" chambered guns have chambers a bit longer than an actual 2�". When the fold crimp replaced the roll crimp length of the hull was extended a bit as the new crimp used more of the hull's length thus cut down on internal capacity.
The load remained essentially the same. It was proved at that point in time this had virtually no effect on the pressure. The "Loaded" length of the new longer shells was no longer than the older ones with roll crimp, thus there was adequate clearance for the crimp to unfold without resistance. The one major caveat to be aware of is these shells a "Bit" longer than actual chamber length should only be used in chambers having a normal or longer forcing cone. "DO NOT" use than in a chamber which has a sharp step at the end rather than a cone. The end of the fired hull Should not lap into the bore itself, a bit into the cone is no big deal.
The pressure to which the shell itself is a Big Deal, IE SAAMI vs CIP etc. & the older the gun the bigger the deal.

2-piper, You answered the question for me perfectly. Thank you very much. This particular gun has the short chambers , but someone has relieved the forcing cones, probably for the very reason you state. By the way, is that statement by Greener in The Gun and its Development, by any chance?

Yes that is where I read that statement, as I recall he had a chamber drawing which accompanied it. As I recall the date is 1910. Anyway a good bit of what is found therein was written in earlier editions of The Gun so unless one has access to all of his writings its hard to say just when a statement was made. All I have by W W Greener is this reprint of his 9th edition of "The Gun & its Development." Have the 1834 reprint of his Father's work The Gun (William Greener).