Newsgroups: rec.crafts.metalworking
Subject: Re: shear & tension calcs steel
From: Robert Bastow <teenut@home.com>
Date: Mon, 20 Sep 1999 05:32:31 GMT

 Clark Magnuson
> <cmagnuson@home.com> wrote:
> 
> > I bought a 45/70 today. It is a Handi rifle [break action]. I wanted to
> > do some calculation to see if it could be loaded to .458 Win Mag like
> > pressures without the gun blowing up.
> >
> >  The hinge pin is 3/8" in diameter and the case of the
> > cartridge is .5" in diameter. The force = (pressure) (area) =  [50,000
> > psi][(.5)(.5)(Pi)/4]  = 9817 pounds
> > The shear stress = force/ area = 9817 lb/ [[(3/8)(3/8)(Pi)/4](2)]=
> > 44,444 psi {the (2) comes from the fact the pin will have to shear in
> > two places}

You are making a seriously erronious assumption here!

While I am not familiar with the detail design and lock up system of the "Handi
Rifle" I can tell you thet the primary mode of failure of any break action rifle
(or shotgun) is not shearing..But BENDING!!

The action body will bend at the junction of the horizontal and vertical
faces..This will leave the case head unsupported while under Extreme
pressure..Resulting in either a primer pocket blow ou or a case head rupture.

Both events are likely the last thing you will ever see!!  In a bolt action it
is serious enough and they are carefully designed to channel the resulting blast
of white hot gasses and molten brass away rom the shooter's face.  

In a break action you have no such safety backups and the result will be akin to
a Shaped charge going off in your face.

BTW..The 458 Magnum is the LAST cartridge you want to be fooling with!  It is
loaded to the max. as a factory round..to try to get acceptable performance from
a case that is now recognised as being too small.  The factory load is severely
compressed and even in a modern bolt action a great deal of "freebore" is
required to keep pressures down!

If you want a good single shot in a "Dangerous Game" loading..Go with a Ruger #1
...I have seen those in up to .577 Nitro Express!

teenut

Newsgroups: rec.crafts.metalworking
Subject: Re: shear & tension calcs steel
From: Robert Bastow <teenut@home.com>
Date: Tue, 21 Sep 1999 06:33:57 GMT

Clark, it is not physically possible to collect a Nobel prize for mathematics
AND a Darwin award at the same time.

You are going to have to choose!!

teenut


Clark Magnuson wrote:

> The latch lodges between the receiver and barrel. The contact is .16
> x.61". The hinge pin is 16 degrees off the center of barrel measured
> from the breech face. The shear force is then [sin (16 degrees)] 9817 lb
> = 2706 lb of shear. The shear stresses = F/A = 2706/[[.16][.61]] =
> 28,000 psi shear stress on latching surface of barrel. The latch itself
> sees 28,000 psi of compression.
> Clark

Newsgroups: rec.crafts.metalworking
Subject: Re: shear & tension calcs steel
From: Robert Bastow <teenut@home.com>
Date: Tue, 21 Sep 1999 06:37:19 GMT

Why does that not surprise me??  ;^)

Building up for the BIGGEE!!  HUH!

teenut

Clark Magnuson wrote:
> You should see my face now. I have had a lot of accidents.
> Clark

Newsgroups: rec.crafts.metalworking
Subject: Re: shear & tension calcs steel
From: Robert Bastow <teenut@home.com>
Date: Tue, 21 Sep 1999 16:45:22 GMT

In a Rolling Block action there is an arc shaped segment cut in the underside of
the breech block.  As the hammer falls, a matching arc shape on its upper side
engages and locks the block in place.

At the moment of firing there is a true metal to metal lock up making the
rolling block a pretty strong action.  Certainly stronger than a break action,
but a bit springy for maximum accuracy and strength with modern pressures.

teenut

Gary Coffman wrote:

> On Tue, 21 Sep 1999 06:25:39 GMT, Clark Magnuson <cmagnuson@home.com> wrote:
> >Isn't that a FALLING block?
> >Clark
> 
> No, Mike is talking about a rolling block action. The only thing
> holding it shut is the tension of the hammer spring and the
> inertia of the block (around the axis of rotation). Definitely not
> suitable for high power cartridges, but Ok for the little .22lr
> cartridge.