XS60C PCP Repeater project

[RHytonen]

I've been messing around with this idea: I'm calling it a "V port".

Plenty of plenum could be eliminated by cutting at just enough height to fully clear the bore, and by using a ball end mill... but you get the idea. Both ports are bore size in length (.177), and even wadcutters feed beautifully.

I just looked, and my GEN II .22 barrel is very different.
There's only one band of barrel isolation, not two;
and it's isolated by two, and not three O-rings.
All three ports are therefore in the same radial plane perpendicular to the barrel's axis.
Much less possibility (1/2 the real estate, in fact) for port expansion, and never could rival a GEN I, right?
As rsterne suggests, only the most trivial amounts of air could reach the aux ports, and they're essentially wasted on the GEN II. At least in comparison, its potential will always be less than the GEN I, and it's probably less inherently powerful out of the box, being unavoidably port-challenged in comparison.

The GEN I must have two valve exhaust ports,
and/or different (extra- branched?) transfer porting in the receiver, right?
It also makes me wonder how the probe can be long enough to get a pellet
beyond (what I call) the "aux" ports, and still clear the breech for pellet insertion.

I have measured this GEN II's ports by a go/no-go test , using a set of graduated Morse drill blanks, and measured the barrel with an admittedly cheap digital readout caliper.

The 0.585" barrel's od is thinned to 0.463" for that single isolated port "band," and has the (Morse #16= 0.1770"=) 4.49580mm main exhaust-fed port at 6 'clock,
and two, (Morse #43= 0.0890")= 0.22606mm each, ports at 10 o'clock and two o'clock,
or maybe even 9:30 and 2:00, they're not very precisely located.

If the aux ports, as I suspect, are separately isolated and fed on GEN I,
then I missed out on even more than I thought, and paid more for a lot less,
in not knowing about it until GEN I was long sold out.
I probably shouldn't have allowed all the enthusiasm for GEN I to cloud my judgement

The time was right for a PCP (even if the budget was not and would never be,)
but I might have done better with a B51 ( I would have been in for $300+ either way)
- except they're not (and weren't) available in the US in .22, and I'm not a paper puncher. 
Like you, I'm a garden guarder and tinkerer, with some technical vision (however inexpertly supported by technical skills, equipment and experience for the genre, compared to you and most here.)

What has been your assessment of the RELATIVE (more extreme) power
possibilities for GEN I v GEN II?

Am I wasting my time on the less promising platform, as I suspect?
I get the impression, having it open, that it had been "improved" only from the POV
of those with very different, even opposing considerations to my own.

[StevenG]

MM has said he will have more GEN 1s available in .177. He might even have a couple of those left. You can always get a barrel and have it machined to fit. I am not sure what garden pest would stand up to a .177 making over 20ftlbs with a 16 grain pellet though.

If anyone can make a GEN2 into what you want it probably is stalwart though. I know he mentioned a while back  a desire to turn a uramex fusion into something larger calibered. That is the same gun as your GEN 2.

[rsterne]

A few points to make here....

1. The Gen 1 only has ONE exhaust port in the valve, ONE transfer passage in the receiver, and ONE barrel port....
2. The PLENUM that we require to get the minimum pressure drop during the shot in a regulated gun is IN FRONT OF the valve seat.... The bigger it is, the less the pressure drop during any given shot....
3. Any excess volume between the valve seat and the base of the pellet (such as the "V" Port cavity) will DECREASE the pressure at the pellet because the pressure in the reservoir/plenum must expand to fill that space, and that pressure loss can never be recovered and will decrease the power of the shot....
4. All that is required to bring the barrel port up to the same area as the bore is to make the port LONGER (axially) than it is wide (ie oblong or oval in shape).... The only downside it that the pellet must be loaded slightly further forward....

Bob

[RHytonen]

Thanks, rsterne - but I'm now even more confused.

If the second segmented section of the barrel (shown in a .177 what I assume is a GEN I
-as I think I remember the three barrel O-rings being a difference between the GEN I and GEN II)- 
isn't addditional exhaust port area,
to provide added post-valve charge to behind the pellet,
then to what are it and its ports connected (if it had them,
before "V-porting" which I had assumed erroneously, it did?)
 - and to what purpose ?

Additionally, why else would that separate barrel section even exist?
Is it just blank, to support the loose fitting barrel? In that case using it
by connecting to the valve's exhaust, say, by cutting away the separating wall, doesn't sound like a terible idea to try - as long as you have a way to push the inserted pellet past it..

There's no way for me to see the actual gun from all angles
(as I can the GEN II) so it's hard to picture.
I would have to see all sides of the removed barrel

Has anyone noticed and mentioned or discussed the two extra ports
in the GEN II (,22) and I just missed the posts/threads? 
Seeing those ports was news to me.

How about the second isolated barrel section in the GEN I?
Or, is it specific instead to the .177 (Possibly even GEN II?)

-Rod

[stalwart]

Rod, when the repeater conversion is done, the first 2" of the barrel have to be removed, and it gets re-cut. You don't have to worry about any of the Gen1 vs Gen2 differences...

The V port will not have nearly as much extra volume as the stock Gen2 set up, and slightly more than the Gen1... but, it is only useful when the slight slot Bob mentions isn't enough. The V will not be of any use for smaller calibers.... it can only help when the port size needed can't be had with a single slot due to fit issues. The pic is not representative of actual sizes... I made those experimental cuts to see 2 things: How fine a bridge could be had without weakness, and to check how thin it could be while supporting the pellet for smooth feeding.

The idea was also to see if I could get enough port area for a bigger bore, in total, without moving the valve forward or making a longer valve body. I used a .177 barrel simply because it is going to be converted, and that section will be cut off anyway.

Bob, your point #4 is correct, but there is also the fact that the stock valve is not long enough to get a bore size port for .357, but a square exhaust can get it close (80% or so).

Guys, I'm all over the map here for good reason. I'm trying to standardize all the dimensions possible, in search of numbers that can allow the max number of upgrades (bores) for 1 part #. There are a couple more things to try, and I'll know what can be done using a stock valve body w/mods. A custom valve (as we can choose the port location, size, and shape) will allow all kinds of madness. 

My Gen2 was the first time I had seen multiple ports, and although it seemed to make sense, I couldn't figure out why the holes had to be so far apart... causing both excess volume (which I was taught is also called plenum... perhaps not), and a long twisted path. The V is an attempt to have our cake, and eat it too. One thing is for sure: There is no need to have multiple holes so far apart... a tiny bridge supports the pellet well. And, a V with 2 holes of a realistic area will be very small  compared to the radial design that seems to work well enough to produce in mass numbers.

I picked the sweet spot on Bob's graph (200FPE) and did a bunch of homework. I concentrated on .32, 9mm (.356), and .357. I found that the most choices in bullet weight and size, and the most choices in molds... are had (hands down) in .357. Johninthecamper is tooling up to produce .357 in sizes as low as 80gr... and Lee makes molds as small as 105gr... so, I'm going to see if I can do a .357 that hits hard 3 times on a charge.

Wish me luck??

 

[rsterne]

First of all, the only useful plenum is on the pressure side of the valve.... between the valve seat and the pellet any extra volume is wasted, in fact worse than that, it reduces the peak pressure seen by the pellet.... and that peak pressure is the most efficient part of the shot....

Secondly, I've never heard of anyone managing bore-sized porting in a .357, and certainly not in a 3/4" ID tube.... nor do you need it for 200 FPE, unless you want to do it at 2000 psi.... A 75% boresize, round barrel port is 0.267", and in fact running bullets you can go a bit larger to 0.281" (79%) and not have a loading problem.... That is what I'm using on my Hayabusa, and it's seen 257 FPE at 3000 psi, and will shoot a 9 shot string averaging 220 FPE from 3000 psi down to 2200 with 132 gr. bullets on 460 cc of air (22 CI tank plus 100 cc in the tube, unregulated).... That 856 - 876 - 856 fps over the 9 shots, just a 2.3% ES.... and the efficiency is 1.28 FPE/CI to boot....

No need to get fancy.... just stay with a single, round 9/32" port and you can get what you want easily.... Don't forget, to supply a 0.357" port you will need a valve throat of over 3/8", and that will require more hammer strike than I have in my Hayabusa (145 gr. @ 1.45") which only has a 5/16" throat.... I don't need to wish you luck, only convince you that you don't need to get greedy....

Bob

[stalwart]

You are full of good news today! The valve/block I showed earlier has just enough room for a .270 round hole. Can be done with a stinkin' drill. This is gonna happen.

I'll save some madness for later. 200 FPE is a good goal, and (I believe) will sell well locally.

Just loving these 60s... 

[RHytonen]

Rod, when the repeater conversion is done, the first 2" of the barrel have to be removed, and it gets re-cut. You don't have to worry about any of the Gen1 vs Gen2 differences...

The V port will not have nearly as much extra volume as the stock Gen2 set up, and slightly more than the Gen1... but, it is only useful when the slight slot Bob mentions isn't enough. The V will not be of any use for smaller calibers.... it can only help when the port size needed can't be had with a single slot due to fit issues. The pic is not representative of actual sizes... I made those experimental cuts to see 2 things: How fine a bridge could be had without weakness, and to check how thin it could be while supporting the pellet for smooth feeding.

The idea was also to see if I could get enough port area for a bigger bore, in total, without moving the valve forward or making a longer valve body. I used a .177 barrel simply because it is going to be converted, and that section will be cut off anyway.

Bob, your point #4 is correct, but there is also the fact that the stock valve is not long enough to get a bore size port for .357, but a square exhaust can get it close (80% or so).

Guys, I'm all over the map here for good reason. I'm trying to standardize all the dimensions possible, in search of numbers that can allow the max number of upgrades (bores) for 1 part #. There are a couple more things to try, and I'll know what can be done using a stock valve body w/mods. A custom valve (as we can choose the port location, size, and shape) will allow all kinds of madness. 

My Gen2 was the first time I had seen multiple ports, and although it seemed to make sense, I couldn't figure out why the holes had to be so far apart... causing both excess volume (which I was taught is also called plenum... perhaps not), and a long twisted path. The V is an attempt to have our cake, and eat it too. One thing is for sure: There is no need to have multiple holes so far apart... a tiny bridge supports the pellet well. And, a V with 2 holes of a realistic area will be very small  compared to the radial design that seems to work well enough to produce in mass numbers.

I picked the sweet spot on Bob's graph (200FPE) and did a bunch of homework. I concentrated on .32, 9mm (.356), and .357. I found that the most choices in bullet weight and size, and the most choices in molds... are had (hands down) in .357. Johninthecamper is tooling up to produce .357 in sizes as low as 80gr... and Lee makes molds as small as 105gr... so, I'm going to see if I can do a .357 that hits hard 3 times on a charge.

Wish me luck??

 

I for one definitely do wish you luck - it;s never that simple, for any change. But let's talk about that 2" length loss (as well as the necessity to re-port.. It sounds like something would have to be done to recreate the (more complex than we -or at least I- knew) stock porting; and even increase it at least to compensate for the lost length. (You know my mania for barrel length.... and power. It's "do no harm," there.

btw, I wasn't considering the increase in post-valve plenum significant, only the increase in port diameter over just considering the single large one, as I suddenly found I had to do in trying to analyze porting and i.d. the choke point.. This gun seems to do better stock than most of its size, price point, and air pressure, at least from what I've read from owners, not manufacturers or vendors,(and not having owning many guns myself.) But it would be a shame to lose ANY power in exchange for the repeater convenience. If that were the case I would not make that choice.

With the present gun, (if I can call what's currently a bucket o'parts a gun again,)a very tedious day of measuring ports and a little math, has brought me to the conclusion that the choke point is definitely the valve. Even not increasing the barrel porting to max. for the caliber (which it would be a shame not to do if you have to cut the ports off anyway,) the factory porting with the small auxiliaries MUST do something (or they definitely wouldn't bother) and losing that edge would also be a shame. So, by extension, would be neglecting to push those ports' sizes, and matching up the valve and even the receiver - measurements having shown the receiver porting is the largest of the three, stock.. Not having checked the matching I can't say whether that isn't just to correct for any expected mass production mismatch. I would increase even that to the new max, though.

But before being reminded of the loss of even stock ports, necessity to re-port any way, and losing 2" of barrel length, I'm starting to think I shouldn't have discarded the LW barrel idea. Sure beats having to cut the tube. Then again if you're buying a barrel, and having to redo porting, why not increase the caliber, &/or go to an even longer, or a PB barrel....and having to redo the valve....and.... .oO(&$*#&%@$ dark side....

[stalwart]

Rod, the 2" only brings the barrel more even with the tube... you should have no reason to have to cut the tube. Anyone using the stock F sight will have to mod it for clearance (continue MM's mod another 2").

Mike presented these guns as "tinkerer's guns". They certainly are, and I would have no interest if they weren't. I would go 1 step further, and classify them as "kits". To me, they represent the best possible value as raw material. Like a model kit, they allow any level of sophistication in assembly... and that alone keeps me interested.

[rsterne]

Yep.... KISS (keep it simple, stalwart)....

Bob

[RHytonen]

(dupe- sorry)

[RHytonen]

MM has said he will have more GEN 1s available in .177. He might even have a couple of those left. You can always get a barrel and have it machined to fit. I am not sure what garden pest would stand up to a .177 making over 20ftlbs with a 16 grain pellet though.

If anyone can make a GEN2 into what you want it probably is stalwart though. I know he mentioned a while back  a desire to turn a uramex fusion into something larger calibered. That is the same gun as your GEN 2.

Thanks, and I understand your point -but I have other reasons as well, to stay with .22 for now.
My other rifle -a Benji- is a .22, and for economic as well as experimental control reasons, I prefer to stick with the one pellet caliber for rifles, and use .177 for pistols. The JSB Exact Jumbo Heavy domes are working well for both, and their Jumbo Monsters were even starting to work well with the FD before I decided the nice new gun was well past its deserved initial barrel cleaning, exam/documentation, and trigger polish. It's getting bottle fed next week, and I think the already powerful gun's valve will benefit from a few hundredths bigger drill and maybe a feed improvement (like moving the spring out of the flow.)

If it improves the way I expect, having already loved its power out of the box, once I put it back together I will not want to tear it down and do without it right away like this! So I wanted to do as much as I know I will be doing this first time. That may mean moving the valve spring to the rear and making a new shaft, and even poppet. I know I will be replacing the delrin(?) spacer (XS's "Plug," or what I call the "anvil" with heavy wall 4130 tube - that's easy. And since a foot is their minimum purchase, I may experiment with different lengths, for minute improvements in safety on the front side (as Bob S. has astutely observed elsewhere,) and adjustments in striker *impact* behind the mounting screw.. I'd love to make that striker heavier for its size, and maybe more of a 'deadblow' type (birdshot-filled?) device.

Hopefully Eric can also help with the issues I'm having pulling the bolt (a medical issue with my back.
It actually hurts more to cock the gun than pumping up the air to 1600, which is shockingly easier than pumping the Benji!)
 
I really wouldn't mind a lever -but only if that can be done without adding an operation (cocking AND chambering.) And the lever can be almost a foot long, I don't care.
(Rack & Pinion/gear section operating the bolt, maybe?? Dunno how airgun levers work yet.) Left side is OK, I will always be using at least a bipod. And I will probably be changing this stock when I see what tank mounting choices I can devise for the 22ci. I may wish they made an even longer 2"d. tank. I may possibly get a reg extension to move it back AFAP toward the gun's CG.
A bipod, maybe as part of the metal barrel band it desperately needs, is definitely coming.
Rod

[RHytonen]

Rod, the 2" only brings the barrel more even with the tube... you should have no reason to have to cut the tube. Anyone using the stock F sight will have to mod it for clearance (continue MM's mod another 2").

Mike presented these guns as "tinkerer's guns". They certainly are, and I would have no interest if they weren't. I would go 1 step further, and classify them as "kits". To me, they represent the best possible value as raw material. Like a model kit, they allow any level of sophistication in assembly... and that alone keeps me interested.

I love tinkering (especially $)((# polishing - ie tinkering with "the cheap stuff," been doing it all my life - not always by choice. it's a peculiar kind of bragging rights... )
and actually I never could resist it. Remember my first airgun was a P17...

I just really blew it this time, missing out on GEN I (.22 only please) and thinking I could fix it.
But it took being struck down as an invalid to get me away from more strenuous hobbies and back into  airgunning and the fora.

It's just sometimes rough in retirement (fixed income) to remember no kit ever contains all the parts.
(*looks back @ post #1 of the thread...)
Anybody know where I can find XS60C parts? (The barrel band was once metal.)
Metal Triggerguard stop?

To those lucky ducks with GEN I's:
Was this part (trigger stop)ever metal?
I realize I'm assuming it was.

The "anvil" -valve/hammer "plug"- is easy, 3/4 id .133 wall 4130 tube...for a spring reversal valve mod, anyway.

And BTW I did finally get the front sight off. Only a few marks on the barrel where the visegrips bit right through the padding. (I did choose the spot where the band falls
 
I *Thought* I posted the pic of GII parts (and shot count line target) as someone requested,
but can't seem to find it now.
-?-

(Two solid months of pain and sleep dep, waiting out the delay for surgery, does little good for one's  disposition, or patience. For that, I apologize to all wherever it may have reared its ugly head..)

But I'm still determined to make gone the plastic.
Back to ordering metal parts to make a GEN II into a GEN I,

-and maybe a little psychotherapeutic break to shoot that toy T4
and contribute as much CO2 as I can to the WV atmosphere.
The plants love it....
(OK gimme a break - I did invest in lead-free.
The T4 likes tinfoil anyway,
H&N Field Target Trophy Greens are its favorite...
now get off my back! oops, no pun intended...

If you want me tomorrow I'll be on my back porch
littering the lawn with tin from the T4
-8mags, no waiting-
(And on the phone buying the household's new resident FDPCP more metal gifts.)

I wound up making targets for T4 plinking today.

Rod

[stalwart]

Got some samples from John, for the MG .22. They fit perfectly... weigh 30gr.

Any suggestions for lube?

Rod, yes, the part behind the trigger group is metal on Gen1.

[RMM]

Got some samples from John, for the MG .22. They fit perfectly... weigh 30gr.

Any suggestions for lube?

Rod, yes, the part behind the trigger group is metal on Gen1.

Those look nasty!!  In a good way of course.   I don't know if you're going to have to resize them but if you do I've used Alox with great results in .45 & .38 powder guns.  I've also used dry moly, throw a teaspoon or more in a vibratory tumbler and let the bullets impregnate themselves by gently bouncing off of each other. 

Erik you and your co-conspirators amaze the heck out of me, so please keep doing it. 

[rsterne]

Here are the swaged bullets I intend to try in the MG .22 cal barrel....



They are NAA 30 gr. (actually weight 30.6 gr.).... and the price is certainly right at $8.00 for 250 bullets....

http://northamericanarms.com/accessories/cb-accessories/cb-parts/cbb250.html

If they prove to be accurate, that is less money than many .22 cal pellets....

Bob

[stalwart]

I'm going to try them, too. If they work, they'll make a heck of a deal. What is their OAL?

[rsterne]

They measure 0.366" LOA.... longer than a Baracuda/Kodiak 21 gr. but shorter than an EunJin Dome 28 gr.... They function perfectly in a .22 MRod magazine.... (and obvious no problem in a PRod mag.)....

Bob

[stalwart]

You are nothing but good news lately, Sunshine!!

 

So many ways to play... almost can't wait for winter.

John's are .485". It's snug, but they fit in my adjustable 60's (Sean Pero reamer) chamber, and shoot nicely. I'll get chrony results, just for fun.

[rsterne]

Wow, that's long for a 30 gr.... My 41.5 gr RWS bullets from Holland are only 0.469" LOA.... Both are 0.224" diam, for a .22 rimfire barrel....

Bob