Micky_mick and I will be posting our tube builds here. All are welcome and may we all learn from each other.

I will?

Thanks for volunteering me.  ha ha.

I am planning to make a tube gun in 7.62x25 using the bolt from a pps43 and pieces of the lower receiver.

So far I have the tube and a pps43 lower.  I have a 10 1/2" barrel ordered from gundoctor.

I'm still in need of a FCG and a trunion.  I was thinking about going with an old trigger group from an ak parts kit.

here's a photoshop picture of some of my ideas...

I received the barrel and trunion in the mail a couple weeks ago in the mail that I ordered from gundoctor.   It looks nice.  I had him make it 11.5" long and turn it down to .750 for an ar15 gas rail.  The trunion fit in my receiver tube perfectly.

Some pics.

I thought I read somewhere once that the bottom lip on the pps43 bolt must be ground off in order for it to be legal.  Is this true?



Does anybody have any tips for drilling a firing pin hole down the center of the bolt?


Edited by mikey_mick

I see that the lip is ground off but does it have to be?

I dont know that it does, Mine is a striker fired setup and it insures that if the striker follows the bolt home for what ever reason it wont slam fire.

With the lip ground off it insures the firing pin will hit the rim of the cartridge  and cause a jam if the stiker follows the bolt home.

 

It was done on the uzi for the same reason so the general line of thinking is it cant hurt when it comes to NFA compliance

Someone posted an ATF letter to the effect that if the original bolt had a non fixed pin then the answer is no.  That is why the SSR40 can get away with it.  If it had a fixed pin like a sten bolt then yes.  I think that letter was posted here or maybe at another similar board but I cannot for the life of me remembe which one and where it was.

Kevin

That's sure a lovely barrel & trunion from GunDoctor! 

I like the tight looking fit with the tube too!  Can't wait to see more progress on this!

mikey_mick, i drilled mine in a press, get it squared and go real slow w/ lots of oil, clearing the drillings frequently. my bolt seemed to only be hardened on the ends, and drilled easily thru the center portion of bolt. tried to link to my pps43 build but can't for some reason. go to trickyricks pps43 build, page two. my drill bit broke 3/16 from bottom of hole...don't do that!

I think the 43 bolts are just case/surface hardened.

I did an Rc on one 43 bolt and it was very soft. If it was cased, then the case was very shallow. Remember, pointed drills will always drift!

My tube stuff will begin soon. I still have a few cleanup projects to do until I feel free to explore. I will be using a Suomi bolt so I machined a drill fixture for the extractor as the Finns originally did. I will incorporate no welding. The receiver front will thread into the tube. I want to explore having the receiver piercings laser cut but only 80%. I am excited about exploring new territory. This build will use a PPSH43 magazine tunnel and magazines. I bought a five pack of kits for parts.

I received a remington 740 trigger assembley in the mail today that I ordered off gunbroker.  I think I'm getting everything squared away to where I can start drilling the bolt.

My uncle has a nice drill press so I thought I would go over there today and get started but I am guessing he only has pointed drill bits. What kind of bit would I need and where would be a good place to get one?

PPS43 bolt drilling suggestions, at least for the front. Set up your bolt vertically in a vise. Check it with a square. I am working from an antique memory and I will double check things. I opened the firing pin hole to 3/16ths. Where the bolt handle is inserted, the hole changes to a 1/2 hole. A pointed drill MUST NOT be used to complete the hole. I believe that I finished the hole with a 3/16ths end mill. I then tried to drill the hole from the rear with a pointed drill and the hole drifted something awful. The bolt became scrap. My suggestion would be as follows;

1. Continue drilling from the front with a pointed drill to form a pilot hole for the flat bottomed drill on the other side of the handle hole. 1/4 inch deep or so is just fine. Flat bottomed stuff must have a pilot hole or terrible things happen.
2. Use a machine sharpened flat drill or things will wonder. Hand sharpening means that one side of the drill does most of the work and the hole may do bad things.

At this point you can drill a few inches, stop and start the hole at the other end or continue from the front. At this point you are on your own. I have yet to get back to the PPS43 stuff. I must admit that I want to conquer this problem and help people with conversions. Drill just a bit, remove all chips and re-oil. Never allow a hole to fill up with chips. Cutting oil greatly reduces friction. Friction = heat = metal expansion which may destroy drills. A perfect hole, which took two hours to drill, is much better than a ten minute job that destroyed the bolt. If you destroy your bolt, do not despare. Bolts are available. There is a valuable lesson in every failure.

Thanks for the info tommerr.

Here is the result of 1hour of work with a plug-in drill and some old crappy bits.  My uncle is on vacation so I couldn't use his drill press.  Instead I did some non-technical drilling where the hammer will go.
It sucks not to have nice stuff. : (

My design plan have changed a bit.  I plan on putting a stock on it and adding a flash suppressor to the barrel to extend it to the legal 16".

I'm thinking about how I'm going to secure the barrel to the receiver
tube. My first thought was that I could weld the trunion to the tube
but I started wondering about wether or not it would work to pin it to
the tube. I already have to pin the barrel to the trunion so I figure
that maybe it would work to just put one or two pins through the
whole thing?

Any thoughts?