Barrel porting questions

[Terbltim]

Hey Veral,
We started this discussion via email and quickly decided to share the subject with others so lets start over here.

I'm getting my mind right for experimenting with your barrel porting system [forward-slanted ports, very small where they open into the barrel] on a Super Blackhawk (44 Mag).
Mine has a 7.5" barrel which I intend to shorten to under 6" one day.
Your system calls for the ports to begin about 2" rear of the muzzle for handguns, (about 4" for rifles) and proceed with successive port-holes rearward, away from the muzzle, as hole are added.
If the barrel is only 5.5" or 4.35" this puts the ports about mid-way in the barrel.
Is this a correct/desirable location?
I think I understand it but would like to learn your wisdom on the subject.
Thanks for the help in understanding this.
Tim

[Veral]

  I hope you understand clearly that the ports I'm recommending are not forward slanted as if drilled with a straight drill but are drilled with single flute 60 degree included angle champher drills, with the hole punched in square to the bores length, and on centerline.  So the port is tiny where it breaks through the barrel, but wide at the top, with the hole tapering backward and sideways the same amount as forward.   The reason it works is because gasses moving forward at extreme velocity impact the forward surface and back to about the halfway point, imparting forward thrust against only the forward half of the port.  So only a small part of the gasses are diverted, and they don't blast sideways to increase blast, but at a 30 deg angle forward, which throws up a screen to push some of the muzzle blast forward, which is what causes the reduction in muzzle blast.

  Think on the principles laid out above and you'll realize why I say to start the ports a few inches back from the muzzle.  We want the port jets to preceed the muzzle blast, and also want them to act as a jet for a longer period of time than if placed very close to the muzzle.

  I haven't tried it, but believe that if two ports were drilled in, say, a 6 inch revolver barrel, about one inch forward of the frame, one on each side of vertical centerline at about 30 degs, the recoil would be reduced probably more than with 8 holes placed forward, starting just behind the front sight ramp.       That's just a notion I have but never tried, and a part of that notion is that with the far greater chamber pressure at the beginning of the barrel, blast might increase.    Just guessing and pondering.    You see, when I finally found what worked so well, I immediately quit ruining barrels to try new ideas!

  I believe I mentioned in the post on this matter, that the front sight is constantly blackened, with no sheen or shine, by the powder blast, a point which I really liked.

  All other ports which I'm aware of impart near equal force against all faces of the port, and derive their recoil reduction at the cost of atomic type blast to the shooter, and by diverting muzzle blast sideways to prevent it's jet propulsion backward.

[Veral]

  While doing mundane work today I was pondering my answer to this post and realized that I had recommended drilling the ports at about 30 deg from vertical.  They should be drilled at an angle closer to 45 degrees.

  The ports will reduce recoil no matter at what angle from centerline they are drilled, even if all blast straight up, but the blast reducing feature of this system requires that the blast coming forward and out from the ports send out a sound pushing wave broad enough to deflect  the muzzle blast which would reach the ears, forward as much as possible.

In that same vein.  Ports should not be drilled straight in horizontally, as doing so would only reduce recoil but not muzzle rise.  The blast must be directed upward to hold the muzzle down.      I don't believe that I previously tried to quantify the amount or direction of forces put against the barrel by this porting method, so will expound a little on it here. --  I have no way of giving anything like real figgures so will simply explain what I believe might be the forces when magnum handgun loads are fired.  If barrel pressure were 3000 psi when the bullet passes the ports, some of this gass will slam against the forward half of the port surface, but none, or very little against the back surfaces.  I would guess that PERHAPS 3000 psi would exert somewhere around 500 psi against the forward half of each port, but the time is indiscribably short.  Just while the bullet is moving the last few inches out the barrel and until gas pressure falls after bullet exit.  Also the surface which pressure is being applied to is tiny, when square inches are calculated.  Maybe 1/20 of a square inch or far less, per port, depending on barrel thickness.  Again, all the numbers are hypothetical, and given just to make a picture of the principle of recoil reduction which is involved.

[Terbltim]

Veral,
I often think I should visit the forum more often to keep current on the outpouring of information.
Not this time.
In this instance, I'm glad I dragged my feet a little.
It gave you time to add information that was VERY enlightening and important re: what I was getting ready to do...and significantly simplified the project.
I am having a little difficulty locating the bits (types) you recommend but once that hurdle is passed I'll have information to share on this project.
I sure won't keep the results a secret.
Thanks again!
Tim

[Veral]

  Hit MSC.com.   Or do a search on MSC.    It's a monster machine tool company, a bit too much of a Walmart for my liking but they have everything.    You may have problems getting an account with them, if you aren't a company.  If so, search     Machine Tool Supplies         There are many good sources of all types of tooling, such as mills, taps dies, drills reamers etc etc.  All large cities have machine tool supplies.  We don't up here in wonderful no mans land so I have to purchase mail order, and use MSC.