Weird PP700 stuff

[YEMX]

I've started to send feelers out for some machine work.  I'll be needing to modify the barrel, have a new chamber thimble made, a new reservoir adapter made (silver piece, where the reg used to be), and cut down a Mrod tube.  I'm going to have to "glue" the chamber thimble to the receiver, as I'm not going to reduce the OD of the barrel the entire length of it, just what goes into the receiver block.  Will also thread the muzzle end for an LDC.  I have an idea I've been wanting to try for the grip as well...  I hope it works out. we'll see. 

[Rallyshark]

I look forward to seeing what you come up with!

[YEMX]

I look forward to seeing what you come up with!

Same!!  My brain is a jumbled mess of ideas right now!

[YEMX]

Well I'm thoroughly embarrassed!  I forgot that the PP700 has a tensioned barrel, and I forgot about the #1 mod that 99% of owners do to the pistol once they disassemble it for the first time do: drill and tap for a grub screw for that anchor nut in the receiver.    Here I am, wracking my brain thinking about how I'm going to get that nut on there w/o machining down the entire OD of the barrel...  Getting old is fun, eh?      Anyhoo, still waiting on the barrel to come in so I can do some preliminary measurements. 

Here's the plan:

Make a new "reg body", the silver part- since there's not going to be an internally adjustable reg, and it'll be the new tube mount.  I really didn't like the way the factory tube mounted to the gun- so I'm going to direct thread the tube to the PP700.  There may also be some mods done here for flow and such...

Add a 200 cc tank by using an Mrod tube and conversion block.  This pistol will have over 3x the original air capacity.  Since the tank is metal, I also feel comfortable using it as a bipod anchor point using a Dr. Bob tank bipod mount.

Convert to .20 using a HW barrel. 

Make a "take down" carbine, similar to a Air Arms TDR...




A take down rifle configuration would be infinitely easier to make than trying to figure out a folding stock.

Anyhoo, I've ranted enough.  This project will proceed somewhat slowly, as I still have much to consider before sending anything off to be modified/made.

[YEMX]

NOTE:  The parts diagram I'm using is for a Gen2 PP700.  I'm not sure if the part numbers (PN) changed between Gen1 and Gen2.  Just so we're on the same page,  I'm going to refer to components via their PN's in the Gen2 diagram. 

Okay- I'm going to start discussing this project with a machinist, and need some input.  My main areas of concern is pretty much with connecting the new air tube.  Here's the parts I'm talking about:

L to R, PN: 29, 33, 41 on my schematic:


I'm using a HuMa reg inside the air tube to regulate this build, so I'm not concerned about the factory reg guts at all.  I'll only be pushing this build to about 12 fpe, maybe a little higher.  No more than 15 fpe though.  The main parts I'm concerned with are #'s 29 and 33.  I'm pretty much just going to have #41 copied. 

An idea that I had is to essentially combine #'s 29 and 33 into one big piece.  Like this:


This way, I can enlarge this hole slightly and center it:


I'd have the machinist drill the hole deep enough for this port to be drilled, plus a little more (about to the rear o-ring) but no deeper:


Thus I can eliminate the need for PN: 24 (not pictured). 

Again, thoughts?  I really like the idea of #29 and 33 being one solid piece.  That would eliminate a few problems:

- What to do about the empty reg chamber
- No need to make a new #24 w/no hole or a spacer for the empty reg chamber
-  Ensuring the seal between #29 and #24 is good
- Sealing between #'s 29 and 33 which is a known issue
- Potentially improving flow from reservoir

Seems like a win-win by making #'s 29 and 33 a single piece... 

I think it's been mentioned but that port in #29, couldn't I center it in that depression and maybe make it a touch bigger?  Again, this isn't going to be a powerhouse.  I'm keeping it around 12-15 fpe

TIA for y'alls input!

[Backyard Shootr]

That is what I did to mine.

[YEMX]

Ah!!  Backyard Shootr, thank you!!  Is that just a single HUGE port? 

I'm going to have to peruse the "PP700 Adventure" thread...  I'm looking forward to seeing the info in the thread, not looking forward to combing through 79 pages of posts... 

[Backyard Shootr]

Ah!!  Backyard Shootr, thank you!!  Is that just a single HUGE port? 

I'm going to have to peruse the "PP700 Adventure" thread...  I'm looking forward to seeing the info in the thread, not looking forward to combing through 79 pages of posts... 

Yes its 3mm wide by 6mm long. With a 3mm hole thru the middle of the valve.

[YEMX]

EXCELLENT!!!  Thank you much!!

[Backyard Shootr]

You can not eliminate part #24 you have to seal that end up or it will leak air out the back. I drilled and tapped the center of #24 for a 6mm set screw then used red Loctite to secure the 6mm set screw and #24 to #29. Then once it was dry I filled in the voids with J-B WELD. Then for extra security I made a titanium washer and rubber washer to fit inside the breech.

[YEMX]

You can not eliminate part #24 you have to seal that end up or it will leak air out the back. I drilled and tapped the center of #24 for a 6mm set screw then used red Loctite to secure the 6mm set screw and #24 to #29. Then once it was dry I filled in the voids with J-B WELD. Then for extra security I made a titanium washer and rubber washer to fit inside the breech.

I want to make a completely new one-piece part that is a combination of #29 and #33.  If the center bore isn't drilled all the way through, there is no need for a #24... 

[Backyard Shootr]

You can not eliminate part #24 you have to seal that end up or it will leak air out the back. I drilled and tapped the center of #24 for a 6mm set screw then used red Loctite to secure the 6mm set screw and #24 to #29. Then once it was dry I filled in the voids with J-B WELD. Then for extra security I made a titanium washer and rubber washer to fit inside the breech.

I want to make a completely new one-piece part that is a combination of #29 and #33.  If the center bore isn't drilled all the way through, there is no need for a #24...

Oh! Even better.

[YEMX]

...Oh! Even better.

    Yessir!!

[YEMX]

How much clearance do y'all think would be appropriate, between the front of the reg and the rear of the bottle block?  Since the tank and block is just a reservoir, the tube between the reg and tank block wouldn't really be acting as a plenum...  I'm using an in-tube HuMa reg.  I'm thinking .25" should suffice?  I'd like to keep this as short as possible... Though, I'm not yet sure how much space I'll have to work with until at least monday- that's when the barrel is supposed to get here. 

Another idea I had:  If there's enough space between the barrel shroud and tank, I'll get a Clague reflex LDC- and have it go very near to the conversion block...  If I have the room for it, this build will be silly quiet!!  We'll see what I have room for.

[Rallyshark]

I think a one piece combo of the parts listed would be a solid solution, and I really like what Bob did with his! 

[YEMX]

I think a one piece combo of the parts listed would be a solid solution, and I really like what Bob did with his!

Yessir, that's the exact plan I'm sticking with!  Part #'s 29 and 33 (with Bob's mods done to them) combined into a single piece, with a new #41.  I don't want to re-use my #41 due to a groove I made for the regulator...  It didn't leak, but I didn't even have to make the groove.  I was re-reading the HuMa install instructions, and they only say to thread the reservoir all the way in, then back it off a certain amount to vent.  Nothing about cutting a groove in the threads.  So I'd like a new one.  Or maybe I'll just save the cash and re-use it since it didn't leak before... Poop, now I'm torn...   

Now there's a question- can spares be easily bought?  I figure buying a replacement #41 would be cheaper than making it...  Thoughts?

[Backyard Shootr]

If there was away to seal the adjustment hole that goes thru the trigger area then you would be able to cut #29 off right after the first O-ring. That would give more plenum. Not sure if it would make that much of a difference. I thought about tapping it for a set screw but not sure it wouldn't leak air. It would give you roughly a 10mm x 15.5mm of more plenum.

[YEMX]

Eh... Even bone stock, this pistol is capable of 15 fpe or more?  I'm regulating it to 12 or so...  I think the plenum, such as it is, will be okay for this build...

[SilentMatt]

Man, that barrel really IS thin...  At the rear, where the o-rings are, the sleeve is .472" O.D.  The barrel itself is about .392"...  There MIGHT be enough room to make the barrel bore .472" all the way through...  I guess I could secure the barrel with a grub screws in the dovetail- that way they can be hidden when I put on a scope... 

For those that have messed with the pistol- do you think there's enough room to up the barrel bore to .472" all the way through, or will I hit an air way?

I put a Prod barrel in mine when it broke at the threads due to being so thin. It's been a long time, but I think they're 7/16 OD?

[YEMX]

Man, that barrel really IS thin...  At the rear, where the o-rings are, the sleeve is .472" O.D.  The barrel itself is about .392"...  There MIGHT be enough room to make the barrel bore .472" all the way through...  I guess I could secure the barrel with a grub screws in the dovetail- that way they can be hidden when I put on a scope... 

For those that have messed with the pistol- do you think there's enough room to up the barrel bore to .472" all the way through, or will I hit an air way?

I put a Prod barrel in mine when it broke at the threads due to being so thin. It's been a long time, but I think they're 7/16 OD?

Where did you pull that quote from?  I went through this thread and didn't see it...  Also, did you re-bore your receiver to fit the prod barrel, or machine down the prod barrel?  Was yours a .22 or .177? 

Also, those measurements are pretty good- more like .394" for the O.D. of the barrel though...  It looks like the MAX I could go is .470", but from the back, that looks awful thin...  Or would it only be that thin for the length of the valve?  Y'all think it would be a good idea to bore out the receiver to .470" to increase the thickness of the barrel?  I would lose the tensioning feature of the pistol, and I'd have to drill/tap for grub screws and I'd have to match the breech end of the barrel to the original barrel nut, which probably wouldn't be too hard.  THOUGHTS?  Here's a shot from the breech end...  I dunno, looks real thin...




EDIT:  I'd like to go larger on the on the barrel bore and have a thicker barrel inside the receiver, but it really looks like that eccentric valve bore goes practically through the entire receiver...  I don't think it's a good idea to re-bore the barrel hole larger...  I'll just have to run the risk of potentially breaking the rear threads.  I can definitely have the new barrel machined to make the fit tighter, as the factory barrel fits kinda sloppy in the receiver.  The HW barrel steel should be better than chinese steel, so that should also help.  Since this is a .20 instead of a .22, there will be a touch more material between the bore and the threads.  Might make for a slightly stronger rear thread section?  Probably not.  That's really not much of a difference.