2400kt, Bottled, Regulated

[rsterne]

If you upgrade the lower valve screw to 8-32, as per the HiPac website.... and providing you are using the HiPac as designed.... you should be fine.... Obviously additional screws are OK, if you want to do that....

Bob

[BrokeWinger]

If you upgrade the lower valve screw to 8-32, as per the HiPac website.... and providing you are using the HiPac as designed.... you should be fine.... Obviously additional screws are OK, if you want to do that....

Bob

I do indeed intend to install the HiPac system exactly as it was design to be. I saw what happens when big dumb rednecks go monkeying with it.
I'm not sure it's worth mentioning but I have a "high performance" valve from Alliance airworks installed that has an angled port and gives greater volume of airflow.

My intention has been to use the HiPac conversion for both HPA and bulk fill CO2 use. It will be unregulated. CO2 charged primarily, and HPA for colder weather use. Anything I should be aware of/prepared for?

Again I apollogize for hijacking the thred...guess I should just start my own when I get closer to being ready to start buying parts.

[WECSOG]

I think HiPac says the factory screw is sufficient below 2000 psi. Going with a hi flow valve won't affect anchoring requirements.

What I did with my two HiPac'd Crosmans is keep the original screw and add a pair of 8-32 screws, one on each side.

[BrokeWinger]

I think HiPac says the factory screw is sufficient below 2000 psi. Going with a hi flow valve won't affect anchoring requirements.

What I did with my two HiPac'd Crosmans is keep the original screw and add a pair of 8-32 screws, one on each side.

Did you by any chance do a write up on the machining for that?

[BigTinBoat]

I think HiPac says the factory screw is sufficient below 2000 psi. Going with a hi flow valve won't affect anchoring requirements.

What I did with my two HiPac'd Crosmans is keep the original screw and add a pair of 8-32 screws, one on each side.

Did you by any chance do a write up on the machining for that?

here is a good read right at the top of the PCP gate

http://www.gatewaytoairguns.org/GTA/index.php?topic=97198.0

[WECSOG]

No. Actually all I did was drill through the tube and into the valve (with a depth stop), thread both the tube and valve with a bottoming tap, and put an 8-32 set screw in it. Then flip the tube over and do the other side.

[aPpYe]

Hi All,

I figured I would post a couple of pics so you could see what it looks like at the moment:




I am still not quite done with mounting the bottle, but it sits pretty solid as it is now.  I found a scrap of UHMW polyeurethane, drilled a couple of matching holes (to the tube and the bottle) and cut it down to where they look like a couple of giant barrel bands.  They are obviously still rough around the edges, and I hope to clean that up this weekend.  Also, I am likely going to be removing one of them when I jbweld a piece of metal or plastic to the back of the bottle that will insert into the remainder of the factory forestock.  This should make it feel really solid if I can get it to fit snugly into a recess that is in the forestock.  What I ultimately plan on doing is using more of the polyurethane to make my own forestock, a little smaller and with finger grips.  The gun balances perfectly in my hand at that spot, leaning forward just the right amount so it is pointed at the ground when I carry it at my side.  Ergonomics are absolutely stellar.  I thought the 17" length of pull was gonna be too much, but it really feels natural to me.  This is the first pistol grip rifle I have owned.

So far, I have polished the trigger, which made a big difference.  I also touched up the crown with the brass screw trick, and only lightly polished the barrel with fitz and paper towels around a spiral jag.  It is definitely shinier than before...  My cheap multi piece rod broke while I was doing it.  I still haven't polished the leade/bore transition.  When i get a nicer rod, I really want to try my hand at lapping the barrel with molten lead, as I have seen people do on YouTube.  I have my 1377 and an old 22lr that (according to my brother, who gave it to me) "shoots a little squirrely" to practice on.

Anyway, this gun has exceeded my expectations.  In its current state, I am shooting dime size groups (well, consistently under an inch anyway) at 50 yards (scoped and bag rested while I am testing pellets) with the JSB heavies at 900fps.  My goal is to be able to match the 50 yard accuracy of my CZ-452 ultralux, which can do quarter inch CTC groups at that distance. So far, I have not been able to get any of the lighter pellets to group quite so well, but most of them still group at around 1-1.5" at that distance, and I have not had a chance to test everything I have.  Lighter pellets will primarily be used for shorter distances anyway. Crosman destroyers (~1¢ at Walmart) were suprisingly accurate at about 11 turns out, which I would guesstimate to be about 750fps at the muzzle.  I haven't clocked those yet.  CPHP's group the worst so far, with perhaps a 4" average no matter where I adjust the RVA.  I am anxious to try out some of the 9.8gr winchester domes at PA ... They are so cheap!  Anyone have experience with these?

I love being able to adjust to different velocities and really see where I can get different pellets to shine.  Today has been cold and rainy, and I called in sick to work.  I have been shooting indoors with different wadcutters (offhand) and am able to make single hole at perhaps 7 yards or so...  Even the cheap daisies are decent enough at this range. Daisy pointed or hollow point still group at nearly an inch even at this distance... I have the RVA way out to 13.5 turns and I am maybe shooting 500fps or so.  My dad got me an indoor light kit for my chronograph that should arrive this weekend.  I can't wait for it!  This weekend I will be able to plot more velocities and decide on some favorites at different power levels.

So on to the little plastic (neoprene perhaps, like on lock nuts?) thingie that is supposed to go into the RVA, providing friction to stop it from self adjusting...  Was this supposed to come with the RVA?  If not, is there a crosman part number, or a decent DIY solution anyone would like to share with me?  It isn't such a big deal when the knob is turned in a bit and there is already a load on the spring before cocking, but when I am shooting indoors, the knob is turned way out and there is no preload on the spring until the gun is cocked, allowing the knob to turn a little too freely.  I did try using teflon tape with some success, but it felt a little too elastic somehow ...

EDIT:  Bob.  You are starting to become an enabler here!  This airgun thing is becoming quite the obsession for me!  Now, am reading a post you made about a boattail pellet for PCP's and it has me interested in in casting now!  Wonderful.  I am not made of money you know...  Five months ago, I was just considering a cheaper alternative to 22lr, and was only passingly interested in airguns.  Today, I am hopelessly addicted.

Moral of the story:  If you have a significant other who thinks you spend a little (a lot) too much time with your airgun(s), blame Bob.  Okay, so where's that needle ...

[aPpYe]

Okay cool.  I called crosman and they are sending me a new "acetal pin" (CH2009-023) that will work to keep the adjustment knob a little stiffer...  I am assuming "acetal" is similar to the material seen on locknuts that keep them from spinning...

[rsterne]

Acetal is the generic name for Delrin (a trade name)....

Bob

[aPpYe]

Okay, this is weird.  I finally got my bottle mounted the way I wanted and decided to pull the gun apart and put it all back together with everything just so, with some lock tight in a few key locations and generally a little extra TLC.  I did this because of all the disassembly/reassembly that has been done over the last few weeks while tuning, clipping springs, etc.  I thought I had everything really nicely set up!

What I am running into now is some sort of extreme hammer bounce...  Really extreme.  It even happens on the low power settings, but I didn't really notice it until I pulled out my heavy pellets and turned the adjuster in.  I get obvious "Brrrraaappp" sounds when I fire now.  With the adjuster turned all the way in, I got literally a full second, maybe even two seconds of the long burp sound.   Literally!   It sounded like a machine gun.  Any idea what is going on?

When I last took apart the gun, I noticed that the spring was sort of stuck in the adjuster (a challenger RVA), even with the knob removed.  I didn't really think much of it though.  I just left the spring in there and reassembled the gun. Perhaps I should have taken it out!  What in the world is happening???

I am thinking of drilling out a bolt and trying the spring guide mod Bob came up with a few weeks ago where the hammer actually coasts into the valve pin, eliminating hammer bounce.   I am not sure how much advantage I would see with this mod on my gun though.  I really would like to get my gun working properly on its own beforehand...

[BigTinBoat]

Sounds like low pressure. Do you have a test gauge to see what your regulated pressure is?

[rsterne]

If your spring is sticking in the adjuster, my guess is that you used too long a screw (top or bottom) and damaged the spring and it's hanging up.... Whether that is causing the hammer bounce or not I don't know.... The worst hammer bounce I ever experienced was with a very light valve spring in a .35 cal Disco conversion.... When the air pressure got low enough, it bounced until it emptied the reservoir.... Too much preload at too low a pressure is the basic cause of hammer bounce....

Bob

[aPpYe]

I am gonna check out the spring first...  I tested my regulator at 1200-1250psi a couple weeks back, but I may as well double check that.  I did replace the bottom screw on the RVA, but I made sure I used the same length...

This was definitely not happening before this last, partial teardown...

Another thing I did differently upon assembly, now that I think of it, was to clamp the receiver to the tube.  The breech was a little loose on the tube, which prompted this whole thing in the first place. The small, forward breech screw was never removed until the clamps were in place.   I then removed the screw, which was very loose, put some locktight on it and snugged it back down...  After installing the rear screw, I removed the clamps.  I did at least attempt to only lightly clamp things together, but now I am hoping I did not damage something...

I will find out tonight...

EDIT:  Hmm.  I just thought of another difference.  When I last took the thing apart, I degassed it with a 4 inch screw I picked up from the hardware store.  The screw threads right into the knob from the Challenger RVA.  I have done this several times before with no ill effect.  This time, I noticed I a small, low pitched squeal coming from the gun after I backed the screw off.  I then turned it back in (perhaps further than before, I don't really remember) to release whatever tiny amount of pressure was still in the gun.  If I did turn it in too far, perhaps I weakened the spring inside of the valve ...  I know I didn't go all that much further in, but I dunno.

[aPpYe]

Doh!  I haven't put it back together yet, but uh ... I'm gonna say I think I found the cause of my sudden hammer bounce!  My daughter started calling it "Dad's Fart Gun" ...




I guess I wasn't paying attention when I last put the thing together.   Anyway ... relief!

[rsterne]

Is that the valve spring?.... *LOL*.... I didn't realize they used T-----s....

Bob

[aPpYe]

Yep ...     I had some tissue paper stuffed into the tube when I had the gun opened up, just to keep anything from falling in.  Then forgot about it I guess...  I would definitely advise AGAINST the use of tissue paper valve guides...

I have not read it in a lot of detail as of yet, but I saw your thread on your "SSG" valve guide idea.  Very interesting.  Have you seen improvement on regulated bottle guns such as mine, or your QB79 Ninja/$200 PCP?  I plan on reading that thread tonight...

[rsterne]

Yep, good improvement on the Ninja, it's all in the thread.... Works on regulated and unregulated PCPs....

Bob

[aPpYe]

I saw that.  I am definitely gonna be doing this in the coming weeks.  Maybe this weekend!

[aPpYe]

Man ... I am so happy I chose a 24" barrel!  I lowered the pressure AGAIN!  I am down to 1050-1100psi and I am STILL getting high 890's, even the occasional shot a hair over 900fps with the 10.34gr jsb heavies!  This is with the RVA turned all the way in.  I am not sure where the knee is now, as I have not clocked too many pellets at this pressure... I guess I will have to find it again.  The main reason I did this was to see if I could eek out a few more shots per fill before building my SSG.

Thanks again everyone for all your help.  Bob (rsterne) is first and foremost on that list of course...  Rob (BigTinBoat), I got a lot of good information from you as well.  Todd (HappyHunter) provided the tipping point for me going with a crosman instead of a QB... I just love the ultralight form factor.  Last, but not least would be Jason (NervousTrigger) who provided me some pretty good information on massaging my barrel, which I followed pretty closely.  I couldn't have done it without you guys.  Thanks again!

Now, off to the hardware store.  SSG, here I come!

[aPpYe]

I don't want to derail the SSG thread with questions about my specific setup, so I am posting my question here...  First, I was very successful in making and installing an SSG with my drill press, bench grinder, and some dremeling.  I used my smartphone to make a super slow motion video (240 frames per second) of my gun shooting before installation, and it recorded an average of four 4 bounces per shot.  It recorded NO bounce at all with the SSG installed.  I am able to achieve the same 900fps with 10.34gr JSB's as before, and hammer bounce has been stopped cold.  Awesome!

Anyway, I am now noticing that my extreme spreads are quite large compared to before.  Most pellets are spread out as much as 35fps, compared to the ~5-8fps (depending on the pellet) I was experiencing before I lowered from 1200-1250psi.  A couple of days before I made the SSG, I lowered my set pressure to about 1050-1100psi.  Theoretically this would mean more shots per fill, right?  This lowering of the pressure is what introduced the hammer bounce in the first place.  At least, it is what made it sound more obvious.  I was excited that I was still hitting ~900fps with the lower pressure, and I did not bother to check for ES.  I went straight into making the SSG.  At first I was thinking it was the SSG, but I now see that I have the same wide ES with or without it installed, so I figure the problem must be related to the low set pressure.

My thinking is that this Disco valve is not really meant to run at such a low pressure, but I know zilch about how to balance hammer and valve springs for efficiency.  Other than raising the pressure back up, is there anything else I can do to tighten up the ES again?  I was thinking maybe I need to lighten the valve spring, but I don't know for sure so I figured I would check here before taking things apart again.  Currently, the hammer is what came with my 2400kt.  The valve, valve spring and hammer spring are all unmodified Disco parts.  The only other spring I have to play with at the moment would be the spring that came with the original 2400kt valve ... I don't know if it is any different.  I can always go to the hardware store...

This gun is a CCS 2400KT in .177 with a 24" barrel ...