Dennis & Brian\'s Build

I agree with you that the magazine base plate will hit the barrel plate.  The barrel plate is 2.75\" in diameter.  The I.D. of the magazine base assembly is 3\" in diameter.  That leaves .125\" clearance on a side.  Add that distance to the .125\" thickness of the magazine base assembly wall thickness and the .375\" of its plate height and that comes out to .625\".  The depth of the part on the drawing of the base plate is .700\", thereby hitting the barrel plate by .075\".  Is that, what is happening?

Don

Hi !

The barrel plate protrudes into the area where the magazine block fits. ( towards the rear of the gun ) It shows in our picture and in the assembly 3d views. This prevents the cover from closing and blocks the slot where the bullet drops into the bolt carrier by at least 1/16\". Best we can figure all to the print and CD views as being correct, which of course it is not.
We checked everything as to print without finding an error so we moved everything per the posts.

Clear as mud, right ! :roll:

Brian

Thanks Cutter for the info on the ejector problem. For those who may not understand what we ran into I finally got a picture to show the bullet being held at the rear by the bolt extractor and the nose still in the barrel whilst the ejector on the underside of the top cover hits the case. What you get when you have a misfire is a dead stop with a bent bullet. See picture below. The second picture shows the bent case.

Did you keep your ejector the same shape and just move it up 6 degrees or did you change the shape as well?

We also worked today to eliminate misfires and after seeing your post over on the Gunsmithing - Six Shooter thread we added bushings to increase the firing pin force. Brian added a .063\" bushing on his and I jumped up to .080\". The trade off is cranking force required to crank the gun verses the force the firing pins hits with. Adding the .080 is about all we can do without undue stress on the rest of the gun but both the .063 and the .080 seem to eliminate the misfires.

Did you guys shape your firing pin protrusion end at all?

D & B

At 48° the nose clears the barrel plate.
After that I\'m not much help, as I use a drum magazine with a different adapter.
The gun should rotate freely when not cocked. When cocked, only a smooth progression of spring compression.
The alignment and clearance between the bolt/shear screw and cocking ring slot is somewhat critical.
Too much misalignment will cause bolt drag in the carrier.

Lookin Good :!:

[quote name=\"Bzrkr\"]Did you guys shape your firing pin protrusion end at all?[/quote]
Elaborate , not following what you mean.
Thanks !
Brian

Most firing pins are rounded on the end or shaped in some way. I shaped the protrusion end like a blunt chisel or a \" I \" shape like .03 wide . I got the idea from my ruger 22 pistol\'s firing pin. It focuses the force of the firing pin on a smaller surface area.

I don\'t think that a shaped firing pin will work with a round rotating firing pin. Some guys made there firing pins so they would not be able to rotate in the bolt, and then shaped the end of the pin to a chisel point.
bruski

Your right Bruski i forgot that part. The heads of my firing pins needed a flat for clearing the inside diamter of the bolt. They can\'t rotate inside the bolt so the chisel end is always hitting the rim.

These plans are just the gift that keeps on giving. The next problem we ran into when we tried our test magazine was the bullet slot was too short and the bullets would bind at the front of the mag base. We could not move the slot in the magazine back or the rim would fall on top of the extractor so we had to take .15 off the front of the slot in the mag base. This cut that .040 bridge down to .025 but the bullet would now fall through the mag base into the bolt carrier. Since we originally drilled the nose of the mag base we had to grind a cutter to plunge down the slot.

Making the short test mag convinced us that hogging a key way cutter the length of the mag was a good way to break the cutter so we decided to do a two piece mag and cut the rim slot with a slitting saw.

I like the idea of the 2 piece mag.  I\'m working on the oscillator and I\'ve had to make changes because of the drawings.  That, and screwing it all together to avoid the soldering.  I\'ve ruined too many parts trying to solder them.

Don

I wonder if a 3 piece mag would work, to avoid a slotting cutter all together?  Two \"L\" shaped pieces and a spacer between them.

Don

That would work,too. A little less stock to hold on to and keep straight, but workable.

Brian

Finally got back to the gun and started the tripod. We needed to design a yoke to fit the larger casing and make it more proportional to our gun. Due to weight we decided to make the tripod out of aluminum. The yoke is made from 1.5\" stock. We rough cut it on the bandsaw, bolted it to a jig plate and cut it on the Tormach. We then cut the top and bottom to insure they were flat in case the piece warped during milling.

We then drilled and bored for the bolt, bushing and bearing. We will be adding top covers and hinges as separate pieces.

In the video, are you conventional cutting on the CNC with a left hand cutter?

Don

Hi Don,

We are actually climb cutting which is more the norm for cnc machines. The reason is climb milling gives a nicer finish and since cnc mills have ball screws you can climb mill without the danger of the endmill grabbing the work. I often made a very light finish cut on my manual mill climb milling.

Dennis

Hi,

We are climb cutting. For some reason the video makes it look like the cutter is going backwards. Saw the same thing you did.  :?

Brian

I looked at the video again and see now why you ask the question. It does look like it is turning backward. :oops: