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Jaxom · Senior Member

When I orginally ordered my 2300KT in February of 2009, it was my plan to buy parts from Joe to convert it to HPA. It was my desire to have a compact carbine style at that I could stuff in a back pack for a day afield hunting. I didn't want to lug around a "big" rifle with me.

Whether good or bad, for some odd reason, I just never seemed to have the money to order the parts from Joe. And for the brief time that I did, I totally forgot about my kt project.

In a way this was actually a good thing though. Joe has since come out with newer products and this also gave me a chance to learn more about hpa's and what issues to take into concideration when working with such high pressures.

Reading Bob's threads helped tremendously! In fact, after read his threads, I can seriously say that I wouldn't plan or build a project now without including a hammer spring adjuster. You've got me convinced Bob, that this is a "must have" accessory.

Had I modified my kt the way I had orginally planned, I'd never be able to install an adjuster, because that's where the adapter to hold a tank would attach to the rear of the pistol. In addtion to not being able to install an adjuster, my orginal plan was flawed.

As explained on his website, Joe mentions that unless the tank is completely empty or a cut off valve is installed, you cannot (or should not) attempt to remove the tank. This would be hazordous to one's health. So now not only would I not be able to install the adjuster, I couldn't make this a "back pack" gun that I wanted it to be.

Then I seen that Powermax that one guy tried selling here. And I thought, "AH HA!! that's what I need!" Sadly, it has been pointed out this gadget isn't entirely safe. So, about a week ago I posted in the main form that perhaps a newer, safer design could be designed if we put our noggin's together. Since I was planning on using the valve out of my discovery and knowing that I'd be using 3 mount points in doing so, I assumed this would take care of any safety concerns.

Since basically I'm just looking to extend the gas tub on my kt, I started thinking if that isn't safe, how can I turn this into HPA, and still be safe and not install a tank on the back end? Then it dawned on me, why not order a discovery gas tube. I could then find someone to cut that down and re-threaded so the quick connect could be installed on the shortened tube.

But, I'm not so sure this would be all that benifical for the effort. Taking some measurements from my kt and discovery, basically I'm extending the tube 7". The new tube would then be 15" long from end to end. This would allow 1" for the quick connect assembly And I'd still have an inch to spare from the end of the quick connect and the end of the barrel. This would serve to help avoid any issues in the future when I go to add a muzzle break.

But the more I've thought about this, I'm not so sure this would be the ideal solution either. By cutting off nearly 11" from a stock discovery gas tube, I would be limiting the volume of compressed air I could hold, resulting in lower shot count, and requiring more frequent refills. And that would be if I did no addtional mod's on the valve, port and such. Not the ideal situation when hunting afield.

I do know that when I can (hopefully very soon) buy a folding stock adapter with power adjuster from joe. But as to how to convert my kt to hpa now, I'm totally confused.

Suggestions?

Jax

rsterne · Moderator

It really depends on how much power you need and the shot count you want.... and whether or not you want to pack a pony bottle with you for refills....

My 2260 PCP Carbine uses a 14.5" barrel and a full length 2260 tube with Disco valve and extended valve front.... I fill to 2000 psi and shoot down to 1200 and get 16 shots per fill at 20 FPE.... ie 700+ fps with 18 gr. JSBs.... I have a 48 ci. tank with 2000 psi regulator and that gives me about 15 fills (ie ~250 shots).... On a good day of Grouse hunting (getting my limit of 5) I have yet to have to refill from the tank even once....

I use my own RVA and a fill fitting from B&A.... but the Disco one would work also.... The gun uses a stock Disco valve (except for the extended front end) and stock transfer & barrel ports.... It's a pretty darn simple design with plenty of power for my purposes.... Wink

If you want more power, you will probably want to use a Disco tube.... or a bottle.... or you will get too few shots.... The first decision you need to make is what you want to accomplish....

Bob

Jaxom · Senior Member

This is full on hunting gun I wish to build. Game, squirrels, rabbits, pigeon/dove, ground hog if within reasonible range. Figure depedning on range and conditons, I'll be using anything from crosman premiers to kodiak's for knock down power. I have a fairly nice sized back pack, so taking a pony tank along isn't that much of an issue. Max power isn't nessary, but a bit more power to push the heavier kodiaks along would be nice. Figure I'll be using the stock discovery valve form the rifle, discover hammer spring with adjuster and mild port work done.

After posting, I hit the usual places to see who's got what. Notice that bryan and assoc will cut discovery tubes down to what ever size I want. Figuring 16" long...

I also noticed that he also sells a 2260 tube. If I were to use his bulk adapter (assuming it's threaded the same way my kt is) I can only bulk fill with co2. That limits my hunting a bit, we can have snow through mid april in the spring and as early as 1st week of October here. That makes co2 useless as far as I'm concerned for hunting.

I can't tell from the exploded view of the disocover parts, whether or not the fill assembly is screwed in or pressed in. Anyone know?

steveR56 · Member

If you con't need quiet, just go with stock disco tube ,along with valve a$$. and fill assembly @ 20+ good shots per fill. the fill a$$. screws in to stock tube. Or pay extra to cut tube, get less shots.Depends on what your needs are.

steveR56 · Member

If you con't need quiet, just go with stock disco tube ,along with valve a$$. and fill assembly @ 20+ good shots per fill. the fill a$$. screws in to stock tube.

Jaxom · Senior Member

I was afraid someone was gonna say that. I wonder if they'll rethread the tube for me, if I have it cut down. Then I can just order the gas assembly from crosman and screw that right in.

Full sized tube defeats the concept of a back pack ag. And frankly, I'm not too partial to how that looks either...but that's just me.

steveR56 · Member

I would think that if they cut Disco tubes , then they should re-thread- just ask them, they are top shelf. have a B&A boss valve in the other 2240 in my pics- In mine , I wanted a longer shot string, so went with full length tube- you will need disco valve a$$.,gauge a$$. and fill a$$.- all from Crosman- cost me @110 for all- I added the stock also, but all total with 2240 base weighed maybe 4 pounds. 16" barrel and 14" tube should give room for **dust collector**-just less shots

rsterne · Moderator

You still haven't said how much power you are after.... so it makes it impossible to make recommendations....

A stock .22 cal Disco is about 22-23 FPE and 25-30 shots
Ported & Streamlined valve with RVA can max out at ~30 FPE and ~ 15-18 shots
Bored out valve & heavier hammer spring & 2400 psi fill can get up to ~40FPE and ~ 12-14 shots
Fully modded I got up to ~52 FPE in .22 cal and ~58 FPE in .25 cal and ~ 10 shots

These are with a full length Disco tube.... Pick your power level and live with the shot count.... A shorter barrel will cut power, of course.... Rolling Eyes

Provided you use an extended valve front end (to cover the roll-stamp) in a 2260 tube, and anchor the valve properly, HPA should be OK up to about 1900-2000 psi.... That is what my Grouse gun is....

Bob

Jaxom · Senior Member

Maybe I didn't word it right, but I did explain what kind of power i'm seeking and what I'll be using this gun for, in my responce to your comment... 3rd post in thread...

Also noted in that comment, that after reading over Bryan's website, that my only option with the 2260 tube would be to use solely co2, not what I wanted to do.

What I didn't mention here, was that I've already emailed Bryan. I was inquiring about either having a disco tube cut and re-threaded or if the 2260 tube he sells has been rolled stamped and what pressures he recommended I operate at.

Mark5043 · Silver Status Member

Jax you already have a Disco right?If your looking for a pack gun with HPA power, you already have what you need.... especially if your on a budget which you have indicated.All I do is separate the Disco's action from the stock...put on a trigger group from a 22xx/13xx,or take mine off my 2300KT,and slap on a crosman carbine stock in the field.It takes only a couple of minutes to set up in the field,and the whole thing fits nicely in my pack dis assembled... Mr. Green

rsterne · Moderator

AirGunEric · Site Admin

I wish someone would spell out "assembly" completely so the forum filter doesn't keep kicking in and confusing people! or maybe even just "assb." would be more useful.

Jaxom · Senior Member

My appologies bob, since I don't have a chrony, I don't normally think of things in fpe's. That's why I didn't post any numbers.

For the record, I've seen the ground hogs around here, and I doubt they're near 20lbs in size. Of course I could be wrong. So let's go with that....to have 1fpe per pound of largest critter I wish to hunt, that'd be 20fpe's.

Alzo.... I recieved a reply from Ron over at b&a. His first comment, was stressing that NO 22xx gas tube should be used for HPA applications. He didn't go into details as to why, but I will assume it has to due the roll stamp. I'm also starting to think the thickness of the tube wall may not be thick enough to withstand those pressures even without the roll stamps. But that's only my theory.

rsterne · Moderator

I can't guarantee that the tube is the same material as a Disco tube.... although Joe was told by Crosman that it is.... However, it is the same diameter and wall thickness....

If you feel more comfortable with a Disco tube.... then go with that....

Bob

AirGunEric · Site Admin

All the Crosman tubes are likely to be the exact same steel/size. Why? They all come off the same production line in their New York factory- which is somewhere around 25% foundry activity- the bluing and stamping/printing are, AFAIK, when things start to differ.