doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 2 1/2 vs 2 3/4 chambers

Randy:

Make sure to check your forcing cones. Most older guns have steep angled, short forcing cones which can lead to hull damage as seen in one of the responses above when using 2 3/4" hulls in 2 1/2" chambered guns.

To avoid such hull damage, simply trim down the 2 3/4" hull length to 2 9/16", use your existing reload data, toss in an overshot card, and crimp as you always do for 2 3/4" hulls. Any increase in pressure from the overshot card should be slight. And the hull should fully open in the existing chamber without damage from the forcing cones.

Recipe: plastic Cheddite hull two and three-quarter inch
19 gn Solo 1250, Cheddite 209 primer, SG 16 wad
7/8 oz lead
1211 fps, 6200 psi
Recipe from Accurate Arms

I fired a couple of these in the 2 1/2 inch chambered 1 frame Parker Bros 16 ga.
The resulting fired hulls showed no damage or feathering, also, I don’t know if it is significant, but the felt recoil when only wearing a T-shirt was no different than when firing the same shells through the same type of shotgun with two and three-quarter inch chambers, or no difference when shooting a 2 1/2 inch shell through the 2 1/2 inch chambers.
I decided to go ahead and order the same SG 16 wad in the short version and load 2 1/2 inch shells

Thanks Russ that is an idea I may try

FWIW, the old Remington Game Loads in 16 gauge in Black were 2 9/16" length after firing. If you can find these anywhere they will work. I shoot them out of my factory Fox 16 gauges with short chambers. 2 9/16" were what these older guns were designed to shoot. I do find them snappy, but they are imo no more snappy then the Gamebore 2 1/2" factory loads in 16 gauge currently being sold by Clay Shooters Supply.

Those Remington game loads are still out there. Reloaders love them.

According to testing done and published in the DGJ several decades ago, shooting a 2 3/4" shell from a 2 1/2" chamber, IN A 12 GAUGE, raises the pressure max in the 600 to 800 pssi range. As you go to smaller gauges, the increase in pressure gets bigger. But for a 16 gauge, you can think in terms of 1000 psi.

So a 6000 psi load becomes a 7000 psi load. Both levels safe for guns we generally think of as requiring low pressure loads. Assuming barrel wall thicknesses are appropriate.

Not to put too fine a point on it but pressure generated has very little impact on recoil and what it does is quite oblique.

You rightly point to weight of the ejecta and speed it's accelerated to as key factors. The other significant element, in terms of what we feel, is weight of the gun, which is a moderating influence.

Its been my observation that far more damage is done to older gun by shooting shells with too much recoil than too much pressure. Its just that when you exceed the pressure threshold, the results are a little more likely to send you to emergency.

There are various tested recipes like Randy's above, using different components. Using Herters (Cheddite hulls) and other components that don't match Randy's, I've had one recipe tested by Tom Armbrust with 7/8 oz shot with an average velocityof1182fps; pressure 7420 psi. I won't list all the components. The value of the reloaders'group is that you can search for components you already have or know to be available. If you hit on a recipe you like, stock up on components to keep from
getting caught short.

If you have problems with cases like Drew H. pictures a lot of times 2 3/4" components can be used in a 2 1/2" hull with a shallow roll crimp. If someone else mentioned this I'm sorry I missed it.

I make a simple hull cutters that work with a utility knife from copper plumbing fittings that index off the rim instead of the base wad so hulls are always the same length,

10ga 3.5 to 2 3/4(I have a loader set up to star crimp 2 3/4 10ga and they work in my 2 7/8" 10ga double.


12ga any length to 2 1/2"


sorry having a bit of trouble posting a pic, I think I've got it.

Very good idea with the copper tubing,Oskar, I had been sticking a short dowel rod inside the shell and eyeballing it.

I can sit in the living room with my wife(wife time is good) and cut a whole bag of shells, all the same length and never have to measure. Cut off just fall in my lap, no digging the out of a BPI Trim Dr.