Standard disclaimer: DO NOT begin a suppresor project without first obtaining approvale from any and all state and Federal agencies: ATF Form 1 is required from the feds.
This is part 2 of my attempt to build an integral suppressor on a Mauser VZ-24.
My next step was to turn down the barrel.
I started at the widest point on the barrel and worked my way down and back a little at a time
After the barrel was turned down (I did it in stages to keep the barrel as "beefy" as possible) I cut it down to 18 inches, recrowned it, and threaded it at 5/8 ths inch National Fine. Remember that the barrel is cut down because the "overtube" will extend another 8 inches beyond the muzzle to allow for a series of expansion chambers. Without cutting down the barrel the length would be too unwieldy.
The chamber end was also threaded. These threads are the same as the barrel reciever threads, 1.1 by 12 TPI.
Here is the barrel after being turned down, cut down, crowned, and threaded. The next step is porting.
Ok, a few things about porting this puppy. I wanted to maintain as much accuracy as possible so it was imparative to drill the ports into the center of the grooves without touching the lans. Now to some of you folks out there this may be childs play but I was clueless and agonized over it for a long time. How to do it? Find the center of a groove at the muzzle and measure back from there. You must know the twist rate of the barrel (there is also a way to figure this if you do not know) and having only four lans and grooves makes the process much easier. With four lans and grooves once you determine the location of one groove then a few 90 degree rotations and you are drilling into the center of all four grooves.
Here is a pic of the barrel with one line of ports in it. Above the barrel is a dowle rod with a thread twisted around it. The thread is twisted in the same ratio as the grooves in the barrel. As you can visualize here each port is some variant of 90 degrees off of that thread. Pretty neet hu?
Another pic showing the ports at 90 degrees to each other
Some information on drilling the ports. Because I wanted them only going through the grooves I had to ues a very small bit. 5/64ths to be exact. That makes the bit very flexable and very problematic. Allow only enough of the bit to expose from the chuck as is necessary to drill the port. Any more only allows for the possibility of "deflection" of the bit as you drill the port.
Also, it is very important to use only sharp bits, no more than two holes per bit (a drill doctor comes in handy here). Use LOTS of cutting oil and go very slow. Watch out for any kind of "chick, chick" noises that may be the bit chipping, because it can happen. If it does change bits and clean out the hole to get ANY pieces of the bit out - if those pieces remain, it will only chip the new bit.
Ok, here is the barrel after porting is finished.
Notice right in the middle where there should be a port. It looks like a smudg mark on the barrel. Actually if you blow up the picture to its full potental you will see that you are seeing through both ports all the way through the barrel!
Alright, that concludes part two. I'm not as far along as I hoped but I'm getting there. Next step will be to sand out all the guid lines on the barrel and polish. Then I'll make the end caps, muzzle support and tube. Then the baffles for the last 8 inches. Stay tuned. . . . .
