Any Interest in 6mm ? - Build Thread

[rintafile]

Well....i have been sending couple PM's to Al ...One was July 17 and one August 9th and haven't got any answers yet. Must been busy time on NOE.... I've been ordering molds other places like MP-Molds.For .25 cal, .22 and .223 . MP-Molds has sale 25% off and free shipping wordwide.  And checking castboolits forum too.
 But yeah sure i'm interested but it could take while when we get enough interested signed to get that mold.There is "new" winds blowing at NOE...Most of group buys are slick sided HTC coating models which are useless in our hobby.
 I'm a bit confused.... Having get answer usually in few days but have seen others complaining in other forums that they won't get answer PM nor emails either...

And go MRI at Saturday depending result I may need to go back surgery again so...Well I get more information on that at August 29th when doctor calls for results

[rsterne]

Good luck with the back surgery, Teemu.... hope it goes 100%....

Bob

[rintafile]

Thanks Bob. I hope too If surgery is needed

[YEMX]

So I got my China tank today- the Ninja valve fits beautifully... The gold and black contrast is nice too...  Anyone know what the typical oring type/size is for 450cc-500cc tanks are?  The factory Ninja tank oring isn't going to cut it methinks. 

[dyotat100]

How did you get a ninja reg in a Chinese tank? I have only seen 18-1.5mm threads on the carbon fiber tanks.

[YEMX]

How did you get a ninja reg in a Chinese tank? I have only seen 18-1.5mm threads on the carbon fiber tanks.

It's an aluminum tank, 450cc 4500 psi, that's threaded for 5/8-18 UNF.  LITERALLY the only tank that would work with the Ninja reg, sized for a airgun.  This thing is a beast too... as in HEAVY.

[YEMX]

I wonder if it would be possible to either have a custom made mag for these 6mm boolits?  Or would an existing mag work?  I'm thinking the Bowman boolits will be too long...  I'm not worried a bit if I have to single load them, the magazine was kind of an idea that popped into my head.

[rsterne]

You might be able to have a custom mag made, without a cover plate?.... The maximum length in a .25 cal mag is 0.450", you might be able to grind that out and get to 1/2", but I've never tried.... The 6mm Bowman is 0.57" long.... The opening in the receiver for the Mag. is 0.70", so using a .25 cal single loading tray is a no-brainer....

Bob

[YEMX]

.25 cal single loading tray is a no-brainer....

Bob

I was sure this was the case, I just wanted to make sure- thanks again Bob!!

Any thoughts on what size O-ring would go in this tank of mine? 

[rsterne]

Sorry, no.... The standard Ninja tanks use a # 016.... 5/8" ID to fit over the threads, 3/4" OD to fit inside the recess in the end of the tank.... However, if the regulator is undercut for a thicker O-ring, you may need a # 112 or a # 113.... Basically, use the one that after you put it over the male threads (or recess) fit just inside the groove in the end of the tank, and for thickness touch both parts before they are screwed hard up against each other.... so that the O-ring is under slight compression when installed....

Bob

[YEMX]

Any specific type?  I'm assuming big box (if the even have those sizes) store o-rings wouldn't cut it?

[rsterne]

BunaN are fine, either 70D or 90D.... It's a static application, so nothing fancy is required....

Bob

[YEMX]

Sweet!!  I'll go snag some to try out this weekend!!!

[rsterne]

The mould for the 74 gr. FN, available as GC or PB, and also with a Lyman HP Pin, are now in the store at NOE.... along with the shortened version I requested....

http://noebulletmolds.com/NV/index.php?cPath=25

Bob

[rsterne]

I got all my material for this build a couple of days ago, and decided the first thing to do was to turn down the back of one of the tubes to fit the stock.... I got a piece of 1.25" OD x 0.120" wall 2024-T3 tubing from Lloyd Sikes, which I plan to use for the .257 version, as I am going to build two guns at the same time.... The 6mm will be a regulated gun, using the 500 cc 4500 psi CF tank I got earlier.... and the .257 version will be an unregulated version having a 300 ccc reservoir that can be filled to 4500 psi.... I hope to tether it at about 3800 psi.... The straight tube, unregulated .257 version will look something like this....



The tube is long enough, and a thick enough wall, that I was able to turn down the back 7" to 1.15" OD to fit inside an AR style stock.... It will be used directly over the tube, no separate buffer tube or threaded attachment required.... I used a steady rest on the lathe to support it (since it won't fit through my headstock) and turned down the butt end.... Here is a photo of the stock slid into place.... There is still 0.070" of wall remaining, so plenty of strength.... Note you can't do this with a 1.25" OD x 0.095" wall tube, because the remaining wall would be too thin.... so the 6mm version which uses that tube will have to have a conventional threaded adapter to hold the buffer tube assembly....



With the tube slid in until the back of it hits inside the back of the stock, there is a bit under 1/4" of smaller OD tube showing, and the trigger will be mounted so that the LoP can be adjusted from 12 to 16".... At a 14" LoP it will look about like in the photo.... I have to mount a piece of aluminum barstock on the bottom of the tube to prevent rotation of the stock, and provide holes for the fore-and-aft adjustment feature.... The stock can be slid right off the back for access to the preload and gap adjustment of the SSG using a socket and/or screwdriver.... I will be using Prod trigger groups on both builds, with a taller sear supplied by Lloyd, which is intended for the 0.095" tube wall.... Since this tube is thicker, I will be milling a flat on the bottom of the tube and the top of the trigger group to get the correct sear engagement....

Bob

[Prouzy]

I really like your design.  Is this single or multi shot, I cannot recall. 

[rsterne]

Both these will be single shot.... I am considering either machining the loading tray into the barrel.... or using a spindle with an integral loading tray so that I can index the barrel.... haven't decided yet.... I like the idea of drilling the receiver straight through at a large diameter (I have some 12" long drills) instead of having a small (loading) section in the middle and having to drill from both ends.... That tends to cause misalignment between the barrel and bolt.... at least I seem to have difficulty getting the alignment perfect when I do it....

The other advantage is that I can make both receivers identical and just have different ID spindles.... or machine each barrel to suit....

Bob

[Prouzy]

I suspect that would provide about as straight a feeding/seating as you can get.  And a loading tray into the barrel, I envision something similar to how the QB barrels are machined?

[rsterne]

Yes, drill the chamber into the breech end of the barrel at the appropriate diameter, and then mill half the barrel away, leaving a loading tray like the QB setup.... The drawback is you may need a very long chambering reamer, it has to go from the back of the loading tray to the front of the tapered leade.... If using a spindle to index the barrel, the chamber and leade is machined into the barrel, but no port, and a lip that inserts into the spindle.... A matching recess is in the front of the spindle, housing an O-ring to seal against the barrel, and the port and a parallel chamber machined into that.... then the back half is milled away to form the loading tray.... NOTE that the spindle must be secured into the receiver as there is considerable rearward thrust acting on it, and also forward on the barrel (pressure x barrel OD^2 x PI/4).... If they are not separate pieces, the forward force on the barrel is reduced, as is the rearward thrust on the bolt face.... because the pressure only acts on the bore area (where it seals against the bolt face), not the barrel OD cross-section.... Another alternative is to make the loading tray a separate piece, so no load on it, just on the barrel and (inserted) bolt.... Lots of things to think about, strength-wise, either way....

Bob

[Prouzy]

Yes, drill the chamber into the breech end of the barrel at the appropriate diameter, and then mill half the barrel away, leaving a loading tray like the QB setup.... The drawback is you may need a very long chambering reamer, it has to go from the back of the loading tray to the front of the tapered leade.... If using a spindle to index the barrel, the chamber and leade is machined into the barrel, but no port, and a lip that inserts into the spindle.... A matching recess is in the front of the spindle, housing an O-ring to seal against the barrel, and the port and a parallel chamber machined into that.... then the back half is milled away to form the loading tray.... NOTE that the spindle must be secured into the receiver as there is considerable rearward thrust acting on it, and also forward on the barrel (pressure x barrel OD^2 x PI/4).... If they are not separate pieces, the forward force on the barrel is reduced, as is the rearward thrust on the bolt face.... because the pressure only acts on the bore area (where it seals against the bolt face), not the barrel OD cross-section.... Another alternative is to make the loading tray a separate piece, so no load on it, just on the barrel and (inserted) bolt.... Lots of things to think about, strength-wise, either way....

Bob

This is very interesting, as it makes me consider the various configurations such as the QB, Sam Yang, amd my PBBAs with threaded barrel:receiver with no porting.