Project "Silent 22-45" Part 2

[L1A1Rocker]

OK, obligatory disclaimer here: DO NOT start a suppressor project without FIRST obtaining your approved Form 1 in hand, PLUS any state paperwork that may be necessary in your state.

First let me apologize for not posting this sooner. My grandmother has been in very poor health the last month and has finally past this last week on Mother’s day. I had planned on posting this last week but that had to take a back seat. Now, on to the good stuff.

This was my first foray into turning stainless steel and I was very surprised at how well the stainless bar stock took to machining. The little splinters were not pleasant at all but the material was very “workable”.


Before I could start turning out parts that had threads on them I had to make myself a set of thread checking gauges. I once checked into having custom taps and dies made up and just about dropped the phone at hearing the price. I learned how to make my own custom threads on the lathe. So here is the process I undertook to make a set of check gauges that I will make my other threads to match.

First thing was to face off the end of the stainless steel bar stock





Next was to put my center hole in place for the live center



Now it’s set up to do some trimming down.



Here is a little Vid of turning down the bar stock. Please forgive the unedited videos. I’m in a hurry to get this posted before heading out of town.

http://s79.photobucket.com/albums/j154/ ... rstock.mp4


Now it’s threading time. I’ve been a little remise in posting pics of the threading process so here are lots of pics and some vids thrown in for good measure.

First was to turn down the bar stock to the correct O.D. and cut thread relief on each side of where the threads will be.



And now we can start cutting threads.





Here are some vids of the threading process.

http://s79.photobucket.com/albums/j154/ ... rstcut.mp4

http://s79.photobucket.com/albums/j154/ ... ngVid1.mp4

http://s79.photobucket.com/albums/j154/ ... ngVid2.mp4

And with the threading complete.



And now just for S & Gs, and because I’ve got the tool to do it. . .a little knurling treatment.



And here are my thread check gauges. (sorry no pics of making the tube gauge) All my following threads will be made to these specs.




Now, since I already had the Stainless in the lathe I decided to turn out the end cap.
First I drilled/bored a ¼ inch hole through the entire length of what is to be the end cap.



OK, just being a little coy with the pics here but can you see the end cap in the bar stock?



Here is the cap just before threading.


Here it is after threading and boring.



And now it’s time to cut it off from the bar stock.



And now a couple pics of the completed end cap.




Just a note for all us other hobbyists out there. Be sure to keep you tool bits sharp.




NEXT: A change of stock to aluminum and we’ll turn out the chamber support. This is the part that will be screwed down onto the threads on the barrel right near the chamber. The stainless tube will then be screwed down completely over this and butt up against the receiver. To keep this from unscrewing at the wrong time and in the wrong place it will be affixed to the barrel using a set screw.

OK, here we go again, center hole the bar stock for the live center.



I’m going to skip a lot of what you’ve already seen in this post on this peace so here is a pic with the chamber support turned down and the outside threaded for the tube. The inside diameter is already drilled out for the next step.



And here is the next step. Threading the inside. Now I don’t want to disappoint anyone by not lathe turning these threads but I’m basically a lazy person and will take any shortcut I can.



That is really a great little setup. The tap holder has a center hole machined into the back of it to run your live center into. Pretty neat.

OK, here is the complete deal just before cutting it off.



And here it is laying next to the barrel.



Now getting ready to tap it for the set screw.



Tapping



And now a major F-up on my part. In order to find my mark on where to place the hole on the barrel for the set screw I screwed down the chamber support onto the barrel. I then used an automatic punch down the set screw hole in the chamber support to mark my spot to drill. Now the chamber support WOULD NOT COME OFF THE BARREL!!! Yep, you guessed it! I had disrupted the threads on the barrel and I was SCREWED!!!

Out came the dremil tool with a mini end mill attached. I WAS able to salvage it but it is NOT pretty. It’ll work, but damn. . . . I’ll let the pictures talk from here.








Next peace to work on was the tube support. In the mauser project this peace was threaded onto the muzzle end of the barrel and secured with a set screw. This one will be a little different. This time the peace will be a slip fit. The tolerances will be VERY close with a little bit of firm pressure to get it to actually “slip” onto the barrel. This peace will keep the barrel and tube in alignment so it needs to fit tightly.

I took a little shortcut here and used an end mill to start things off. I had to finish it out using a boring bar so I could keep the tolerances tight.



And the finished product.



OK, that is where I’m at now. Well, not exactly, I was actually in the middle of cutting threads into the tube when I had to leave town but I don’t have any pics of that.

Please feel free to leave any comments, suggestions, questions as I enjoy discussing the project. Don’t get offended however if it takes a while for me to comment back. I’ll be leaving town tomorrow and will not have computer access for a while.

Thank you folks, it’s a fun project and fun to share. I’m just glad it’s taking less time than the Mauser project.

[jimmym40a2]

thanks for taking the time to post it. Good luck with your family. Nice work.

[Jmark]

Very cool, thanks for taking the time to post this.

[JacksonBrowne]

Very cool. Thanks for the update- can't wait to see the end product.

[tmix]

I thought you were never supposed to thread aluminum and stainless together......something about galling the threads?
Why would you make you end cap out of stainless, but not your chamber support?

[wolf]

I thought you were never supposed to thread aluminum and stainless together......something about galling the threads?
Why would you make you end cap out of stainless, but not your chamber support?

never thread bare aluminum and aluminum together
It "might never come apart again

Lube does the trick

[tmix]

I would have rolled the tops of the threads with some emory cloth in an effort to prevent this issue. Just my .02.
(My first choice would not have been to try and mate aluminum and stainless for this reason.)
I've threaded aluminum/aluminum together many times without issue. (Hell, look at a maglite.) It all depends on what kind of alloy you are using and how you dress the threads after machining.

[AAA]

L1A1Rocker,

A couple of tips:

I notice you're using big long pieces of barstock and supporting it with a steady and machining parts off the end of it. If you have access to a horizontal drop style band saw or similar you may want to just cut bits off and machine them in the chuck it's much more rigid that way and less setup.

Re. The threads. As Tmix said, they're a little too rough. If you can't comfortably run your finger over them they need to be smooth out. You can use Emory or scotch bright pads. The problem with using HSS cutters on tough materials like you're doing is, unless they ground properly, they dull very quickly. If you have any threading questions, feel free to PM me. I have a little experience in this area.

[tmix]

L1A1Rocker,

A couple of tips:

I notice you're using big long pieces of barstock and supporting it with a steady and machining parts off the end of it. If you have access to a horizontal drop style band saw or similar you may want to just cut bits off and machine them in the chuck it's much more rigid that way and less setup.

Re. The threads. As Tmix said, they're a little too rough. If you can't comfortably run your finger over them they need to be smooth out. You can use Emory or scotch bright pads. The problem with using HSS cutters on tough materials like you're doing is, unless they ground properly, they dull very quickly. If you have any threading questions, feel free to PM me. I have a little experience in this area.

I agree.

[L1A1Rocker]

Thanks for the suggestions guys!

[canenvy]

is this a baffle?

[wolf]

I would have rolled the tops of the threads with some emory cloth in an effort to prevent this issue. Just my .02.
(My first choice would not have been to try and mate aluminum and stainless for this reason.)
I've threaded aluminum/aluminum together many times without issue. (Hell, look at a maglite.) It all depends on what kind of alloy you are using and how you dress the threads after machining.

In The maglite it isnt bare aluminum

freshly cut clean aluminum tends to freeze together when you tighten it

And for the rough threads ,you also can clean some of it out with a steel brush

[3101]

is this a baffle?

he says it is his tube support....

[Artful]

Tube support
check out part 3 for better idea where it goes.

[Closed Casket]

Glad to see you back.

One thing I noticed with SRT and Gemtech(Quantum) integrals is that the receiver acts as a support for the rear of the tube. Apparently, the front of the receiver is machined to the ID of the tube about .150" back to give the tube a nice clean mating space behind the rear barrel boss. Then the OD of the tube is cut to match the receiver which is about .996".

Both the SRT and Gemtech use a soldered barrel boss on the muzzle end that is attached to the tube. The end of the barrel is threaded and the barrel boss is what holds it. I have a Gemtech that fits really tight and takes a bit of torque to line up the set screw that is under the receiver. this one seems to put the barrel in tension. The SRT is loose as a goose. it actually will turn past the set screw hole.

[Closed Casket]

BTW, the SRT leaks gas and other foul s--t from the tube/receiver joint. Since the Gemtech has an o ring, it does not.

The barrel is turned 1/2" and the threads are 28tpi. It appears a target barrel gun was used on the Gemtech, but the barrel od was not enough to mate to the tube's id so a rear barrel boss was installed there too. This is where the o ring is. You can see the seam of the boss where it meets the barrel.

This was a well thought out setup. The Gemtech appears to be of higher quality in regards to attention to detail. However, the SRT does sound better o the first 2 shots. This may be the 1997 vs. 2001 technology or the added 1" of the SRT. I think there was a big improvement during this period.

I deleted the gemtech cup and spring in the blast area and added a chore boy copper scrub twisted in there. It helped the first round pop tremendously.

SRT has screen in it. I laughed when I saw it.