doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Shell length 2.5” or 63.5-65-67mm.

If you have short chambered gun, 2 1/2” finding proper length shells can be an issue. Looking at some British shell boxes and CIP rules, they say safe for guns chambered for 2 1/2” or 65mm and the shells are 65 or 67mm. 2 3/4” chambers use up to 70 mm. 2 1/2” converts to 63.5mm. But they consider 65 and 67mm as still, ok which tells me a few mm is less important than chamber pressures. Sounds reasonable.

Measuring a large number of Remington 20 gauge hulls most came up with an average just over 2 9/16 “ = 2.5625” = 65.1mm. Weird because we consider them to be 2 3/4”=2.75=69.8mm. Might just be one lot but it is about four thousand, so not just a short box. My Remington 20’s were closer to 2 1/2” than 2 3/4”. A few were 2 3/4” but most nearer 2 9/16”. Winchester AA were closer to 2 3/4”. Length can be different from lot to lot and some of my hulls are old. But as a group the Remingtons measured under 67mm. I just need to sort the longer ones out.

So I’ve decided to use hulls which have an overall length under 67mm and have built a simple gauge for go or no go. Once measurements are confirmed I intend to just keep my pressures down to the 8,00-9,000psi levels for 20 gauge loads. In the end, this eliminates trimming hulls, eliminate special wads and simplified reloading. Have not decided to trim all hulls down to 67mm but I might.

Next I am going to look at a 12 gauge hulls and see if Fiocchi, B&P, Remington, Federal or AA has a similar hull as a starting point. If not, I’ll just trim one group down to 67mm and load as normal.it would be nice to just reload instead of making so many special trips, special shells, wads and adjustments. And I think getting things to fit into a 67 mm shell might be a lot easier than finding things to fit into a 2 1/2”= 63.5mm shell. Going from 70 to 67 has got to be easier than going from 70 to 63.5mm.

or, when in doubt shoot 7/8 oz light target loads in 20 ga guns and 1 oz light target loads in 12 ga gons...ammo mans. are now providing fps data on boxes...most anything under 1200 fps should be fine...

and if you really wanna resolve your worries, have chambers opened to 2 3/4, so long as gunsmith agrees it is safe to do so...

american made gons, usually no problem...

but be extra cautious removing metal from barrels of light weight foreign made gons...

what ever you do, remember the 90 - 30 guidelines...

STFU Ed.

I'm in the process of making a chamber length gauge. I've been trying for fit in all of my doubles and it is pretty clear to me that chamber length is a bit arbitrary. Some guns are a little longer than stamped, some seem to be a little less. Some are quite different from one bore to the next on the same gun. I imagine at least some of this is due to the particular method and tools used to cut the forcing cone, but in any event, there is a lot more variation that I expected.

no reason to reinvent the wheel...

been using one of these for about 30 years now...

https://connecticutshotgun.co/professional-shotgun-chamber-length-gauge-with-integral-choke-gauge/

Says a lot ed. You keep it.

Ed you really area a moron aren’t you? Have you every looked up what factory pressures are? They all run high enough to operate a dirty, semi auto. Even the 3/4 ounce loads are running 9,500 to 11,900 psi. Saying light loads, or low brass shells is a completely dumb thing to do. It is pressure, not the pay load, not the velocity, not how tall the brass is. By your logic the old Active loads ought to be best because they had the very least brass height you possible could have, none. Payload and velocity might be important to recoil but have zero effect on pressure. Please block me and stop responding to my post. You are becoming a waste of keyboard clicks. You bring nothing to any post that I can see. Go back to whatever board you came from, assuming they will have you.

KY Jon - Brent,
I've been in same boat since the disappearance of RST shells and the like. Kent shots hells had some 2 1/2" available, but with only 3/4 oz. of shot. I've recently scored a bunch of Fiocchi and Rio 2 3/4 " shells loaded with 7/8 oz. shot at 1200 fps. I've shot them in my 2 1/2 " chambered Churchill with great results. The hulls show no harm at all to the ends, and they feel better than the RST's did. Perhaps just reloading the shortest 2 3/4 " measured shell to the 20 gauge equivalent would work. I have to admit, I haven't missed the 1 oz. that I normally shot.
Hope this helps,
Karl

careful karl, you too could be labeled a moron, for offering safe solutions to simple problems...

well ky, i have been a member of this fine forum for longer than you have...

if you dont like my posts here...well, then... thats too bad for you...