doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Does a Doll's Head really do much good?

Of course they are! So are running boards. And didn't we just do side clips the other day?

How many guns out there do you look at and, after it has digest umpteen thousand rounds think, "Man, if only it had had a dolls head."

Well I have semi-auto pistols in .22LR, .32ACP & 9mm Makarov by Ruger, Colt, Walther & East German in the case of the Makarov, forget the exact maker. Not a single one of these has any grooves in the chambers or anything else special about them. They will all function reliably even with a dry chamber. I think those grooved chambers were for some special experimental uses which never really took hold.
""IF"" the bolt did not move prior to the bullets exit, it would not move at all. It is true it will have only moved a very short distance prior to the exit, but that movement is sufficient to impart the necessary inertia/momentum to the bolt to continue its rearward travel. When the projectile exits the muzzle the gas rushes out dropping the pressure instantly, if that bolt had not already received its rearward impulse it certainly would not receive it then.

We definitely need a slo-mo film of the action on firing. I left a message to the slo-mo guys who post on Youtube but so far got no reply.

Whatever happens to a break action during firing I feel that it is not what we have been told so far, that the breech face receives a hammer blow from the cartridge head, which flexes the action back, and the explanation stops there. If it does go back it must recover. It does not just gape open from that point on.

A slo-mo sequence might help us understand why some guns shake loose and some do not. And it might surprise us about the utility of third bites and fitting on the circle etc.

So, who knows any slo motion video specialists?

This is not quite what you are looking for, but it does suggest strong backward force by the shell casing against the breech (watch the second iteration of this "experiment" in the second half of the video).

Totally agree on that Shotgunlover.
I'd love to see such footage.
Many people have argued aboud third bites and their construction and that is based on one's understanding of the physics, not real data.
The people who have some real experience are the one who made long lasting shotguns & double rifles that were shot a lot and whom staid in business for a long time.
Westley-R comes to mind as an example.

There are usually two ideas behind the 3rd bite.
- the first one is to keep the gun shut (Purdey et al.)
- the other one is to keep the action from flexing under the backward force at the breech. This is a clear fact of life as otherwise nobody would be rounding the action root.
The old doll's head without bite only tries to address this second phenomenon.

Some third bites do both: Greener (not the best), Webley screw grips ,Rigby Bissell Rising bite ,Ideal , Westley Richards C bolt, etc.

Of course, the best doubles to investigate this phenomenon are not shotties, but double rifles.

Best regards,
WC-

As was mentioned; IMO all the gizmos work if fitted correctly. Were they possibly dropped mainly because of better metal developement and of course cost?

The Beretta 680 series over under with removable and replaceable side thingies is an example of a useless extra that actually does what it is advertised to do when fitted properly. When fitted properly, the barrels are actually cammed toward the breech and stay in the cammed position while in the firing position. You can actually feel the barrels tightening up against the cams as you close the gun. On guns without the replaceable cams, or on guns with barrels that did not come on the action being used, you can't usually feel the beginning of the camming action. The camming action is so slight that the trunnion contact is not lightened to any extent and you have full contact at both the cam and the trunnions. The 680 series action is so "correct" that the fitted thingies are not used in lower end guns and their longevity record is as good as the more expensive models. Kind of like Purdeys with and without side clips and third fasteners. By the Beretta action being "correct", I mean that the trunnions and the cams only serve to add to the locking lugs that protrude from the receiver and plug into the barrel breeches. I think the gun could be safely fired with any two of the features deactivated. It would be an interesting experiment.

Obviously the "Springing Back" of the standing breech upon firing does not exceed the elastic limit of the steel, or it would remain gaped. W W Greener did tell about fitting one of his guns up so that instead of the cross bolt being moved by the lever he simply fitted it with a knob so it could be inserted or removed by hand at will. He fitted a strip of brittle mat'l between the bbl rib & breech. Firing several ordinary service loads up to the max with the cross bolt removed did not break the strip. He continued with heavier loads un til he did begin to break the strip. He then began inserting the cross bolt & continued on with still heavier loads with no further breaking of the strips as long as the cross bolt was in place.

The Greener experiment and Field magazine trials are echoed by Gough Thomas, who also did the dot of plasteline on the action flats experiment.

What would be useful is an experiment that would exclude the Poisson effect as the cause of the phenomena observed.

The plastic limits and recovery of the action during bending imply a forceful process. I am wondering if the recovery of the action body delivers a hammer blow to the barrels, pounding them onto the cross pin.

I also wonder if cheap folding guns, where the barrel lumps are trapped in place via a through cross pin, avoid this pounding. Folding guns seem to be less prone to shaking loose. But that might be a false conclusion drawn from the ones I examined.

The practical reason for my preoccupation with these things is that a clarification would allow more robust design and safer repairs. It is not just theory.

Where is a slo-mo guy when you need him!

For about $5xx you can have a used Casio EX FH100 which will give you about 1000 fps.

But I suspect you'll need higher frame count.