Reamed out the blanks the other day and honed them out. They didn't quite come out as glass smooth as I had hoped, but for testing I'm sure it'll be fine.
As I mentioned before, I wasn't able to locate tubing that was exactly what I needed, so I had to bore out the 0.624" ID tubing to close to the right size. I had a little bit of time this evening, so I faced and drilled out the tubing to 47/64ths (just under the final 3/4" size). Later I'll ream it to 0.75" and run a hone through it to clean up the surface.
You can see a decent amount of material was removed.
Since I didn't have an +8" long drill bit, I had to drill the tube from both ends. If you look closely, you can see a slight step in the middle. That will come out when the tubes get reamed and honed later.
Short video clip.
This is my new thought on going to a sleeve over the receiver design, which is still very conceptual at this point. I would essentially be taking my piece of 1.0" OD x .75" ID material for the receiver and cutting the barrel threads in it, then pressed it into a 1.125" OD x 0.995" ID tube. Then I would finish doing the rest of the machining on the receiver.
Parts are starting to roll in.
On Friday my ejectors and rivets came in from Ruger.
And the UPS man just dropped off the steel for the test receivers.
It wasn't too easy to find correctly sized tubing in anything but aluminum. I could find 1.0" OD x .760" ID, but thought that would be a little sloppy and have a negative affect on accuracy, so I found steel tubing from one of my favorite metal vendors, (http://www.speedymetals.com/) which just happens to be right up the road, in 1.0" OD x 0.624" ID. Because of that I'll have to ream it out most likely with a .749" reamer, then hone it the rest of the way to get it to .750".
Someone's comments got me thinking
" The route I would take would involve a conventional suppressor on the front, with a sleeve that telescopes over the barrel that is the same diameter (1") as both the suppressor and the receiver. A little O-ring groove in the barrel so the sleeve will be sealed at the rear. You could then drill (I would EDM, but I'm not set up for that) holes in the barrel and they would expand into the chamber between the thinned barrel and the inside of the sleeve. Since your suppressor can be conventional, you get all of the advantages of superior suppression but the added benefit of the around-barrel bleed chamber.
If I understand you right, this defeats your purpose of having a monolithic upper but so be it."
Their comment and this video I watched (at the 1:00 mark) a while ago:
got me to do a little thinking. Instead of trying to squeeze everything into a small 1" OD piece of tubing, why not just fit up the frame to a large diameter receiver?
This is a 1.25" OD piece of tubing that I had laying around.
It might cause me to have to make some changes to the mechanicals, but for the increased volume, I think it'll probably be worth it.
Today I spend a little bit of time putting together my testing plan. I want to get an idea of what barrel length bullets will stay sub-sonic. My plan is to start at the factory length barrel and cut it down by 0.1" until it's 2.0" in length and record a number of variables along the way using a couple different kinds of ammo.
I also called up Ruger today to order a handful of ejectors and rivets for the new receivers I'm going to machine for the test barrels. It was about $50 for 10 of each, which should give me a few extra in case I mess up any.
Tore out the LCI, because frankly, who needs that pile of crap?
The next order of business was to take the MK II prints that I was able to find online and turn them into a solid model and print for the receivers that I'm going to make.
This is the print that I started with
And the horrendous looking receiver it yields.
Changed the ejection port a bit to be a little better looking.
All the cuts in the bottom.
Wire frame to see all the innards.
d.wilson mfg works on interesting projects from time to time, so this is the place we'll share some of them.