Subject: Re: Gun Barrel "Drilling"

From: [email-masked] (grego)
Date: Mon, 22 May 1995 10:42:28 -0800

In article <[email-masked]>, [email-masked]
(Michael J. Edelman) wrote:

> [email-masked] wrote:
> 
> :       --I remember seeing an episode, possibly of The Woodwright's 
> : Shop, wherein a demonstration of gun barrel-making was illustrated, In 
> : this instance, a tube was created by wrapping a piece of (hot) metal 
> : around a mandrel. The seam was welded by hammer-blows on the hot metal, 
> : while it was around the mandrel. B4 it cooled too much, the completed 
> : barrel was slid off of the mandrel. Can't recall what happened next... 
> 
> That's the essence of forging 'damascus' type shotgun barrels. Many
> old black powder rifle barrels were made this way, too. It's fine 
> for low pressures but not for the 50,000+psi that can develop
> in smokeless powder cartridges.

 You probably did see it on the woodwrights shop, because Roy Underhill is
one of the head honchos at colonial williamsburg where they keep alive the
traditional crafts. I visited there at christmas and was eager to see the
gunsmith shop, as I too have wondered about the proper way to make gun
barrels (and also have wondered at the dearth of information on the
subject!)  It proved very facinating. From a flat bar of good gunsteel, it
is heated up and then peened into a half round swage block with a hammer
that has a cross section like the wing of an airplane ( the striking face
rounded and approximately the inside dia. of the barrel). Next it is
reheated and a cold bar smaller then the bore diameter is inserted and the
metal is forced by hammer welding around the bar. The rod is then removed,
and the next step is to use a boring machine which uses a long rod
supported at both ends (This is how you get your bore) The rifling machine
is next and uses the same principle as the boring machine, except the
boring tool is advanced by means of a screw mechanism. Bear in mind that
these machines are all made from wood. 
  I have to disagree with the statement that this method is not good for
smokeless powder cartridges. I recently took a gun safety course, and the
instructor showed a rifle which was fired after a misfire lodged a bullet
in the barrel. It was peeled back like a banana along a perfectly straight
seam, indicating to me that the barrel was manufactured from a flat piece
of stock. I have since learned that most steel pipes including high
pressure pipes are constructed the same way. As far as the statement about
not being good for 50000 psi, I have my doubts about that too. most of
that energy is discharged out the barrel. I'm not aware of how much
pressure is developed in one of those old rifles, and i don't know if they
are considered low pressure, but you should have heard how loud them
summabitches sounded!

-- 

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From: [email-masked] (Mark Y. deLevie)
Date: 26 May 1995 15:49:31 GMT

<interesting stuff deleted for brevity, no discredit to authors>
: ...  As far as the statement about
: not being good for 50000 psi, I have my doubts about that too. most of
: that energy is discharged out the barrel. I'm not aware of how much
: pressure is developed in one of those old rifles...

I think the 50,000 psi figure is precisely the barrel-pressure figure.  I
think they measure peak pressure as the powder burns and the bullet accel-
erates down the barrel; the highest it gets would be 50,000 psi in this 
example.  No doubt if you contained the powder charge (one good way to do
this would be by lodging a bullet in the barrel, as you mentionted), the
maximum pressure would be *much* higher than this.  That might explain the
banana-peel barrel...  ;>

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From: [email-masked] (Chris Youngson)
Date: 29 May 1995 23:33:31 GMT

>The Design News mag I just got today had a graph of P vs T for a "A-bolt II
>Stainless Steel Stalker rifle firing 300 Win mag caliber bullets";

Does this magazine deal with the technical side of firearms? I'd be very
interested! 73

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From: [email-masked] (Daryl Bender)
Date: 29 May 1995 20:59:59 GMT

In article <[email-masked]>, [email-masked] (Mark

> maximum pressure would be *much* higher than this.  That might explain the

Missed the beginning but...

T=.0000 sec, P=0 psi
T=.0001 sec, P=2000 psi
T=.0002 sec, P=7000 psi
T=.0003 sec, P=20000 psi
T=.0004 sec, P=35000 psi
T=.0005 sec, P=55000 psi
T=.0006 sec, P=62000 psi
T=.00063 sec, P=65000 psi <-- peak
T=.0007 sec, P=60000 psi
T=.0008 sec, P=49000 psi
T=.0009 sec, P=35000 psi
T=.0010 sec, P=24000 psi
T=.0011 sec, P=19000 psi
T=.0012 sec, P=15000 psi
T=.0013 sec, P=10000 psi
T=.0014 sec, P=0 psi

I would design with some safety factor too. To do otherwise "wouldn't be
prudent, wouldn't be prudent".

Daryl

-- 
Working but not speaking for BNR

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From: [email-masked] (Daryl Bender)
Date: 30 May 1995 20:09:28 GMT

In article <[email-masked]>, [email-masked] (Chris Youngson)

> Does this magazine deal with the technical side of firearms? I'd be very

No its more "just" mechanical engineering design. This particular article
was called "HOT SHOTS" and was about the use of the PRO ENG cad package to
design a screw on unit (about the size and shape of a muzzle suppressor) to
"improve rifle accuracy by altering the frequency of barrel vibrations."

And to Pete, the graph was in KSI which I converted to PSI. This is not to
detract from anything you said.

Daryl

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From: [email-masked] (Daryl Bender)
Date: 5 Jun 1995 21:23:53 GMT

In article <[email-masked]>, [email-masked] (Scot Heath)
wrote:

> For the 300 Win. Mag quoted in another
> post, the highest pressure load is listed as 60,800 psi.
> 
> -Scot

That was my post and it was 65,000psi (even higher) so the moral is never
put a 300 Win. Mag round (or lots of smokless powder) in a black powder gun
or the term "big bang" will have new meaning.

Daryl (thinking of Bugs Bunny for some reason) 
-- 
Working but not speaking for BNR

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From: [email-masked] (Daryl Bender)
Date: 5 Jun 1995 21:23:53 GMT