doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Lengthing chambers and safety limits

There are failures caused by overloads, but most are tracked down to bore obstructions.Even failures in or near the chamber can result from obstructions, such as 20 ga shell in 12 ga or loose base wad from previous shell.
Mike

I don't recall the details of the actual load, perhaps someone here does. Some 10-12 yrs ago maybe longer, Buck Hamlin took a 12ga hammer L C Smith having welded bbls, don't recall now if they were twist or Damascus. Barrels were heavily pitted & considered very poor condition. He lengthened the chambers to 3�" & proceded to begin firing the heaviest loads of Blue Dot listed for 3� shells in Hercules/Alliants manuals. As nothing unusual occured he began increasing the load & continued doing so until he just physically ran out of space in the hull, but never succeded in Blowing it up.
Note also the guns mentioned above which were blown up, Bells's test being at some 30K psi, none blew at the chamber/cone juncture, nor down the bbl.
It should not of course be supposed that in a well designed & made gun, using any normal loads that the wall between the chamber & extractor hole is a particular weak spot. Those which did blow at this point were not ordinary.

Miller, I recall reading those tests that Buck Hamlin did with the pitted L.C. Smith Damascus barrels in the LACA newsletter. I think he actually did eventually succeed in blowing up the barrels with what he called "Nuclear Loads", but it was only after reaching a point where the gun was blowing itself open at every shot. I'm not sure just how that occurred in a rotary bolted L. C. Smith, but the pressures had to be at least as high as Sherman Bell was reaching when his barrels finally let loose.

All the same, I think it should be a felony, punishable by hanging, to lengthen the chambers on vintage doubles. Just my opinion, but proper length shells are readily available, and modern magnum shotguns are just as available should the need arise. There is no need to turn nice original vintage cars into street rods either.

Keith;
Yes the LACA newsletter was where I read of Bucks experience. As I recall it though he didn't actually blow up anything but quit when the bbls started blowing open. I have probably heard of more guns with rotary bolts being blown open than any other bolting system. As I recall this was a big problem with some NIDs, I recall Elmer Keith encountered it with one.
As I understand it when the bbl hook puts enough upward pressure on the bolt it simply cams it around, the slope of the hook being greater than its coefficient of friction. Sort of like pushing down on a watermelon seed & squirting it out.

In the case of the blown Fox I saw, I would have initially voted for bore obstruction, probably a base wad, had the shooter not checked his reloads later and found a couple with no powder charge. That makes a double charge more likely, although it still could have been a base wad.

Re reloading, I'm aware of at least one modern double gun (from a "name" European maker) that blew from a factory shell. Inspection revealed that incorrect barrel boring was the problem, with a very thin spot (I don't recall for sure, but I seem to remember something closer to .010 than to .020) where it gave way.

I have been reloading target shotshells for over 50 years without a mishap, so far anyway
Given the bulk of such powders as Green Dot, Unique, and so on, if I have a double charge of 32 grains in a 12 ga hull I can't get hardly any shot in, so I see a problem right there.
Unlike pistol brass, too easy to put a double load in a 38 Special hull, that's why I charge the hulls and put them facing up in a block 50 at a time and shine a flashlight down to see they are all level with the powder before seating the bullets.
A big worry is to have no powder in the primer will blow the bullet halfway up the barrel = a bulge

MB in MB:
+1 and AMEN to your handgun reloading in units of 50 at a time, and over viewing all 50 cases to ensure each has powder. If one case does not have powder, your eye (MY eye, anyway) will IMMEDIATELY be drawn to the empty case - as it will not conform with the visual pattern. This powder check is an "unintended consequence" of using a single stage loader. This particular check doesn't exist with a progressive loader.
Just my $0.02, your mileage may vary.