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

I just purchased a shotgun with 2 1/2 inch chambers. At present I load a recipe that is 6000 psi in a 2 3/4 inch hull from the 16 gauge society. Do I recall correctly that it would be OK to shoot the longer hull in the shorter chamber if the pressures are low. Thank you.

No issues IMO at that pressure level.

There are 2 considerations when using a 2.75 inch shell in a 2.5 inch chamber: pressure and recoil.

Using a low-pressure load, you should not experience excess pressure that would endanger the barrels, lockup or gun generally.

OTOH, using a 2.75 inch shell in a 2.5 inch chamber will result in a marked increase in recoil. It just does. That may not be good for the stock, and it may lead to other things working loose. If, as I suspect, your gun is a pre-war double that means the wood is >85 years old. Not just age, but also you have no way of knowing what the gun and stock have been subjected to in the intervening years. Probably a steady diet of higher-recoiling 2.75 inch shells for a good chunk of that time when 2.5 inchers were unobtainium. So, you might wind up trashing the stock while saving a few bucks on shells.

It's your gun and your choice, of course.

This might be helpful, and includes a summary of Bell's study
http://parkerguns.org/forums/showthread.php?t=34360&page=2

and
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=607809&page=1

https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=621506

I would emphasize that we have NO modern pressure data regarding 16g and 20g long shells in short chambers.

Some 16g shells (of course after being fired) are shorter than the nominal 2 3/4"; esp. Fiocchi. Components change however and it might be worth doing some dumpster diving for 16g empties at the club and measuring those of different makers.

Winchester Super-X 16g 1 oz 1165 fps 2023

as for the wood, Dave is spot on....

as for the barrels, its about your safety period...

so, find yourself a good smith, with the tools needed to measure barrel wall thicknesses...

have him measure barrel walls in front of chambers and out to 2 3/4 inches...

and then, seven inches down from the muzzles...

ask if he would feel safe lengthening chambers...and shooting this gun with one ounce factory field loads...

also, let us know results of his measurements and his overall opinion of gun...

and what is make and model of 16 ga is this gun and its overall weight...

and if looking for Maine Gunsmith, Cole out on harpswell, comes to mind...

Thanks gentlemen. The shotgun is a Parker Bros 16 gauge manufactured in 1921. It has 2 1/2 inch chambers. Barrel measurements indicate it has not been honed out to remove any pits. I presently reload two and three-quarter inch Cheddite recipe that is 6000 psi for my other Parker of two and three-quarter inch chambers. The wood is solid and not oil soaked. In order to accommodate the new shotgun, I need to order a shorter SG 16 wad. I was just wondering because I have thousands and thousands of components of the prior recipe, and I thought I read here or on the 16 ga Society that it didn’t make much pressure difference to fire a two and three-quarter inch hull in a 2 1/2 inch chamber if the pressures were low. As of now, I cut down the hull and roll crimped the recipe, it just takes more time.

For those worried about excessive recoil, the speed of the load and size of the load are two other issues to factor in. If you are shooting a lighter load with 6,000 PSI and velocity is less then 1150 FPS and you are shooting 7/8 oz loads imo blaze away. Knowing your exact load might give some more insight.

PS. Think about how many 2 3/4" oz loads have been shot in this gun in its life unless it was a safe queen. Folks between 1960 and when RST starting making ammo just shot what they could find and back in those days they shot a lot. I believe (could be wrong) that RST has been making ammo for about 30 years.

I've been loading 16ga, 2-3/4 RGL's for my 2-1/2" grouse gun for about 10 years without issue. 6160psi with 7/8oz at 1119fps. Its the 20/28 load off of the 16ga forum.

In my 20ga damascus Flues, I also shot 2-3/4' reloads @ about 7k. Chambers were 2-1/2" with good barrel wall thickness. I wouldn't think twice about it if the barrels are good.

Hope this helps.

Bill

IF your empties look like this, you have a problem, with your gun



'Feathering' of the case mouth might be a concern



Otherwise, I don't disagree, but believe it is reasonable to find some shorter that 2 3/4" hulls. Maybe someone could kindly measure some current 16g hulls for us?

most likely the barrels are safe...however, if we knew the measurements of the barrels in question, then we could at least put the safety issue to bed...

then we could go to discussing the wisdom of opening the chambers and the forcing cones...

or we could continue to flounder around in the dark, not knowing enough qualitative data to make informed decisions...