XS60C PCP Repeater project

[RHytonen]

Well. I'm sure the more sadistic among you will be pleased - I've officially gone over to the dark side.
After a long talk with the VERY accommodating Mr. Mike, I have ordered what I like to call a 'fakie' Gen 1 - a .22 GenII (unfortunately still not for $100) with no plastic anywhere, and a Power tune. And a pump of course (I'm already engineering a steampunkish way to power-automate the thing - just in case. WAY cheaper than a shoebox if you can weld and have lots of gokart parts and sources.

Eric, we'll be talking next month about that repeater - if I can let it out of my hands that soon
I just may have to wait until I can also afford a bottle and we can do the 24"(+?) bbl, extended tube thing.
(depending of course on how this bbl is..)

Then there's a chrony, fill tank, and a huge monthly *heavy* pellet bill....and the new decision between pellet and bullet!
CURSE this thread and its oh, so generous members with the info & experience....

(and wait'll "Hq" -the wife- sees the Brown Santa stopping here with gun-sized boxes..)
Hope it comes before my spine surgery date, whenever that will be.
I needed an incentive to wake up after that, and pumping the Benji after surgery wouldn't have cut it.
I get flack, from both her and this now 5 weeks of 24/7 debilitating back pain, whenever I try it now.
(In my boredom I even bought a sick little CO2 toy dbl action T4 - a $35 daily deal refurb, which I have to say works surprisingly well for what it is. It's about good for DENTING cans.. and squandering gobs of .177 H&N eco-lights. Groups well at 3 yards.)

It looks like this thread really is my new Bible, and a VERY enjoyable one at that.
Seriously, THANKS guys!
That hospital "dang" better have WiFi.
(huh? ~NANNY~ s/w? 4shame, GTA. Have you SEEN 2000's public TV?)

[stalwart]

Rod, you are in for some real fun now! Velcome to zee Dark Side!

Guys, I figured out how to get a striker force equal to Bob's Hayabusa's. I'm going to get ~36mm stroke, and a boatload of weight out of a mod that's been bouncing around in my head for a while. It will take some real work, but it's in there.

These guns have the potential to get really nasty... and I couldn't be happier. 

[StevenG]

Would it be possible for you to share where you got that oval shroud material?
Or just an update on that project, if there is one.

[stalwart]

I got some resin to test the casting idea... give me a little time, and we'll know if it works.

[stalwart]

Got some stuff roughed in tonight. Looks like my estimates will be pretty close. The striker may weigh a bit more.

Looking at these springs... any suggestions for good replacements for a +20mm stroke? http://www.mcmaster.com/#9657k427/=ssd72s

[stalwart]

Just measured it out, and it wouldn't be hard to extend the tube's "tail" and bore into the stock far enough to expose a decent preload adjuster, just above your hand.

[rsterne]

Love the preload adjuster idea.... persue that.... It will also give more room for a spring.... Springs to try that will fit in a 3/8" hole:

Stock QB 7X: 0.33 x 2.34 x 0.047
McM-C # 9657K427: 0.36 x 3 x 0.051 (the one you found)

Bob

[stalwart]

I'm on it.

We aren't limited to that diameter... if there is any reason giving up some weight would be worth it, now would be the time to discuss it. I could make bigger bolt handles, if we want more spring.

[rsterne]

That spring, and an 80 gr. hammer, should be capable of handling anything up to .30 cal, maybe even .35 cal with a heavier hammer.... If you are going to cock it with the bolt, you don't want anything heavier, believe me.... even that spring at max will be mighty hard to cock.... The only suitable spring I have that is larger is the McM-C # 9657K218.... 0.50" x 4.5" x 0.072".... but I was looking for more than a 2" travel.... I'm sure they have others that are stiffer than the 0.36" OD and can handle travels of ~ 1.5".... However, you would need to make the gun a rear cocker, side cocker, or convert it to a side-lever bolt, IMO.... I do have some Trakar springs, made in Canada, but McM-C have a good selection....

Once again, you need to try some of these things and see the results, before getting carried away.... BTW, increasing the diameter of the spring requires a larger wire, just to get back to the same spring rate....

Bob

[stalwart]

But.... but.... if I can't get carried away, what's the point?

 

I'm just looking for an idea of the max this design can handle. As to weight and springs.... if I build one with the "tail" 12" long (with a butt plate), I can fit about 5# of striker in it...lol. If I make one with a separate cocking lever, a 2.5" stroke is possible. Or, I can make it a reservoir by tapping a micro line in and running it to the front. How about a rear mounted tank?

R&D is my passion. When you talk about "problems"... I see challenges. For me, this is the fun part.

[moorepower]

Maby you should get a block of 7075 and do a rear bottle bullpup! No need for a line.

[avator]

I'm thinking that finding one of these in a time capsule 100 years from now would be mind boggling.....lol

[RHytonen]

Well, the beast has arrived - no pump yet, but it gives me time to build a chrony
and do some barrel cleaning.. polish the hammer, or Eric's teflon thing?
Any suggestions for a FDPCP-specific how2, on hammer polishing & spring source?

How about FDPCP (GEN1) Valve power mods-
(20 degree hole? Port matching? May have to wait until I can afford
the minimal bottle setup, next month...low pressure open valve lock,
with no tank to clear it, would not so good.)

Two questions- ok, three:
1. What's the current state of the art for FDPCP RAW POWER mods
- you know, valve, hammer spring etc.
What's the absolute highest POWER that modders have reached with this gun
(.22, GenII but with no plastic, "power tuned")
I mean, FPE with accuracy over 50Yds and the HEAVIEST pellet available
- screw the shot count for now.

2. Who will build me a turnaround block with a TUBE READING gauge fitting?
(again, for those reading my posts, I want to wrap a 22ci -ie, 14" reg. incl.- tank,
back toward the trigger or the front edge of the action block,
eventually sinking that tank -possibly at a slant following the forestock-
into a customized AR2079 or B51 style thumbhole stock)

3. As I also want a repeater mod, I guess I'm talking to Eric here...
I'm now also wondering if I can find a match(choked, LW?) barrel even LONGER than 24"-
Reading about the first airguns has me thinking Kentucky long rifle... STUPID long range!
(And the obviusly suggested much longer tube, with an extension between the tank and
the reverse block to get the weight back AFAP toward the CG...)
Think 'LR sniper,' rather than a lightweight trail trekking hunter.
Oh - and no one here in WV cares about sound!

[rsterne]

Your question about maximum power with accuracy will vary barrel to barrel, unfortunately.... I have never found anything heavier than the 18 gr. JSB Exact Heavy that shoots accurately at 50+ yards in ANY of my guns, so that limits you to about 36-37 FPE (950-960 fps with an 18 gr. pellet).... You can probably get a bit more power than that in .22 cal, but if you can't hit anything, does it really matter?....

LW barrels are 23.8" long, although you can custom order longer.... If you get a .217 cal airgun barrel from Mike at TJ's you can order whatever length you want, but as you can get 40 FPE without going longer than 24" in .22 cal with pretty much any PCP I don't know why you would bother, other than appearance (and a bit of efficiency).... I don't know if you can get Mike's barrels in larger than 1/2" OD in .217....

Bob

[stalwart]

I'm thinking that finding one of these in a time capsule 100 years from now would be mind boggling.....lol

If things keep going the way they have, the capsule would need a stocker so you can tell what it used to be...lol. I can see versions of this thing that will be unrecognizable as a 60.

Guys, with the stock only bored deep enough to just hide the tube (and allow a small hole, if needed, for an adjuster to be reached)... you can have a 40mm tail. In this context, that's a ton of room.

I found a good way to strip the receivers. I wish I had tried this before wasting a bunch of stripper... Soaking in cheap lacquer thinner lets you easily scrub the coating off with a scuff pad. From now on, any conversions sent need to be stripped... or I need to charge to do so. I highly recommend that 1.5K rigs be internally polished in both the bolt and striker bores. All conversions get the slip coated strikers... it's impressive how well they work in a polished bore.

I will eventually be offering strikers in custom weights, and with strokes ranging from 15mm up... including an adjustable option. Give me time to refine the system, and I'll offer something that can be "Lego-ed" into a wide range of outputs, using only different barrels, bolt noses, and strikers.

All prices I have quoted to date will be valid until Aug 1. I'm trying to drive some costs (mostly machine time) down here, now that I have a better look at them... and, some (not surprisingly) are resisting all attempts to do so.

Rod, you might want to build your gun so it can eventually evolve into a bullet shooter. With this platform, you can pass pellet's capabilities pretty easily.

[rsterne]

I really like the concept of boring a hole 40mm deep into the wrist of the stock, with a smaller hole for an allen key to adjust the preload.... I'm thinking the end plug with a plastic crossplug insert to act as a brake to prevent it from self-adjusting.... should be able to slide the allen key in from the back of the wrist OK.... I assume the rear of the trigger group can mount into a tapped hole in the rear plug?.... How much of an extended tail on the tube do you need for a 1" travel on the striker and 80 grams or so?.... or would you just go 40mm on all of them and change the length of the rear plug?....

Bob

[stalwart]

I have a couple ideas for preventing torsion on the screw which would also keep the head of the screw at the back, so you wouldn't have to reach into the bowels of the tube to crank it all the way up. One incorporates the trigger and stock mount screws. I have to cut protos to prove them, but neither constitutes Rocket Science.... I'm just looking more for the least expensive way to get things done on a production basis.

I have found that if a device ends up successful, every dime spent to avoid excess part numbers will be re-payed tenfold (or more).... so, I'm close to just going for a version with the 40mm tail, and calling that the standard. It's plenty of room, so if you ever see me with a 60 with the tube protruding through the stock... cover your ears! 

1" x 80g is nearly the limit for a tail-less rig, but it will fit nicely. The only reasons for a tail at those power levels, or below, are to get a clean adjuster and less part #s.... and the future option of stupid amounts of energy (my kind of foolishness...  ).

[rsterne]

Eric, per your request, here is the graph about recommended hammer weight for a given FPE level.... I usually try for hammer weights along the "typical" line or just under.... I know that Motorhead uses the "light-fast" line, but that is primarily for low-medium powered, regulated guns, where he is striving for efficiency over power.... PEEK poppets can get away with lighter hammers than Delrin, because they are easier to crack, leaving more energy and momentum to create lift and dwell....



Note that since I made that graph I have decided that most hammers will lie between the lower two lines, it isn't necessary to have hammer's heavier than the "typical" case.... In a really powerful gun the "light-fast" hammers will require either extremely long travel or a spring that will make the gun very difficult to cock.... Values in between the blue and red lines will require progressively more travel / spring as the hammer is lighter.... For the same spring force and travel, the energy (and therefore the lift) is a constant, but a heavier hammer will have more momentum (and therefore create more dwell), which is necessary for driving heavy pellets/bullets.... hence the relationship between hammer weight and FPE....

Bob

[stalwart]

Thank you, Bob.

Guys, the 40mm tail allows a striker of around 150g. As the graph shows, some truly nasty guns can be built around that. It's going to be a fun winter around here.

[rsterne]

I would suggest you concentrate on the area around the red line (ie 250 FPE @ 150 gr.) as much more likely, unless you have some way of coming up with a couple of inches of hammer travel and a REALLY beefy spring.... Still, that's lots of potential.... My Hayabusa can get in that power range with a 145 gr. hammer and 1.45" of travel, using a spring that takes about 25 lbs. of force to cock, and therefore uses a separate side lever to pull back the hammer itself.... You won't do that with a bolt cocker, but maybe with a side-lever breech....

Bob