Ruger New Blackhawk 45 Colt, still strong as ever?

The constriction at the end of each cylinder bore is called the "throat". If the throat is smaller than the barrel you are going to have accuracy issues and at times Ruger has shipped guns in that state. We also have the issue of pre-2007 large-frame Rugers having throats each cut with a different bit/reamer set (all six going at once) so you can have variances between chambers...not good as far as accuracy goes.

To really do chamber reaming right, push a round lead slug through your barrel and measure it, and then set your throats to fractionally over it.

Since I did a completely custom barrel and cylinder for other reasons (in 9mmPara) I set my throats (which in an auto caliber are very long, damn near an inch!) to .3555" to be fractionally over the .355" barrel. I then buy .356 lead hardcast bullets for best accuracy, or at least I would if I could score pistol powder :(.
 
I have had for 10 years, a Ruger Blackhawk 45 Colt made in 1986.

I have only fired one round in it ~~ 23 kpsi.

I know less than anyone above about the specifics of the Blackhawk, but I do know a few things about blowing up revolvers.

1) Revolvers are harder to blow up than you would think if you have not tried it.
2) The failure in an overload is most often a split cylinder. Half the time there is a secondary failure of a broken top strap.
3) Sometimes the timing gets loose as the first failure in a work up. The bolt, bolt slot in the frame, and bolt slot in the cylinder start to make a sloppy fit and the cylinder can be slightly rotated. Rugers come this way from the factory. S&Ws get it from enough abuse. Colts with the Police Positive type lock up do not get loose.
4) The Aluminum frames may bend.
5) Hot work ups for me have never produced end shake, but I find it in used revolvers.

So how do I predict how much pressure a revolver can take?
To a first order approximation, it is hoop stress on the rear of the chamber.
I know it is open ended and should be a Roark type formula. I know a cylinder is not a simple tube shape and it has slots. But it works to a first order.

Thin wall hoop stress is simply, steel stress is equal to the pressure times the inside diameter divided by twice the wall thickness. Lame's thick wall is more complicated, but thin wall is good enough for this.

My Blackhawk measures

0.071" ~ .074" to the outside
0.059" ~ .061" between chambers
The inside diameter of the chamber is 0.484"
I know I should subtract off the brass thickness and residual elastic radial tension in the brass, but it is down in the noise.

If I look at "Speer 12" 1994 45 Colt Ruger and contender loads only, and plug them into Quickload I get 31,700 psi.

The stress in the Blackhawk cylinder steel is then ~ 31.7 kpsi [.484"]/[2]0.06" = 128 ksi

That would correspond to an RC harness of ~ 30.
And that is reasonable, as I can easily machine RC30 4140 steel..., except for where is the safety margin?

Well, it turns out things never yield per the equations with a few 1 ms pulses.
 
Every day I am irritated by posts with inconsiderate abbreviations I do not recognize.

But I feel so innocent and natural when I do it:rolleyes:
 
Many things irritate me, but then I am considered irritable by many. :rolleyes:

Besides the common usage of 3-4 letter groups for any and every word/phrase longer then 5 letters these days (and many here do it constantly as well) one more thing that bugs me is the apparently indiscriminate and inconsistent use of mixing of terms, usually with no explantion.

Such as, ok, "k"=1000 (latin? kilo - metric system) Fine. In print one often sees "$23K" as 23,000 dollars.

SO why are "millions" the letter "m"?

"M" is the Roman Numeral for 1000. NOT 1,000,000,000. So why does every celebrity and sports star that gets big bucks get a "$6M" contract? The press knows they mean millions, but writes M (Roman for 1000) Where has consistency and basic intelligence gone? Its certainly not living in our daily headlines....

pressure measures in psi (psig -pounds per square inch, gauge) I get. I even get Kg/cm2 (kilogram per square centimeter) Converting between the two systems gives me a headache, but I do understand it.

Now (and I say now, only because I am just discovering it) we are blending the terminology of the two systems? Kilopounds? Really?

Where does it end? Are we someday going to be given velocity readings in Meters per Fortnight? (M/F?) Density in grams/hogshead?

Maybe its just me, but I am much more comfortable seeing 23k psi than 2.3ksi
 
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