Maximus Prime

[2K1TJ]

Interesting project!

Curious what your goals are. And why the Prod valve instead of the Disco or.Maximus? Higher shot count maybe?

Two of the Prod breech screws thread into the valve.   I don't believe the maximus or disco valve have enough material in that area.  Even if they did, getting it right with DIY caveman tools would be a challenge. 

It will be the mate to this rifle:



It will start off life as a 22 cal, because that is what barrel and bolt I have.  Plan would be to go to 177 cal (waiting for F&T barrel) and would probably get a regulator at that time.  Mrods are about as heavy a gun as I'd like to carry, but prefer something lighter.

Gotcha

[Buldawg76]

Interesting project!

Curious what your goals are. And why the Prod valve instead of the Disco or.Maximus? Higher shot count maybe?

Two of the Prod breech screws thread into the valve.   I don't believe the maximus or disco valve have enough material in that area.  Even if they did, getting it right with DIY caveman tools would be a challenge. 

It will be the mate to this rifle:



It will start off life as a 22 cal, because that is what barrel and bolt I have.  Plan would be to go to 177 cal (waiting for F&T barrel) and would probably get a regulator at that time.  Mrods are about as heavy a gun as I'd like to carry, but prefer something lighter.

John
I posted on the Disco upgrade thread also but will post here as well. I was not aware that there is a difference between the Disco and Maximus tubes that would prevent the Prod valve from working in the Disco tube. I was not aware that crosman had released the part list for the Maximus yet or did you have them send you one when you called to order parts.

I am interested in this conversion as well.

Mike

[FuzzyGrub]

Well, the box was on the deck when I got home.      I haven't been through all the parts yet, but had to know if the valve was going to work.   Boy, they do put allot of oil in those tubes to prevent rust!  And the answer is, it fits!    I slid the valve in the tube and using two screws from Magnum Airpower, and the exhaust sits dead center in the TP hole.  The screw heads were a very good fit, not like some of the prod/1720T ones I have.  The bottom hole for the 3rd screw is offset, as I suspected.  Not sure yet if  I'll find anther position to make it a 3K psi gun.  But, if not, good to 2400, will be good enough. 

I also slid in the prod gauge block and my fears were unfounded.  It is dead center in the hole butted up against the valve. 

Anyway, going to get back to the inventory of parts.  I'll post some pics latter this evening. 

[Rob M]

this is awesome.so you will have a solid mounting base from the p-rod breech to p-rod valve on the disco tube.. I wonder how we all missed this for soo long.. WELL done sir@

[imadunatic]

Couldn't agree more with Rob. Every time I've seen this asked it was stated that the transfer port wouldn't line up. This is great news.

[FuzzyGrub]

I think everyone assumed this was just a disco in syn clothing.   I did hear some rumblings about the valve being different, but didn't think much of it until I saw some pics posted by a GTA member.

Here is a pic of the transfer port.  My Prod stub tube is shown, and can see the four holes I need to drill for breech.




Here is the bottom view and can see the screw offset issue.




And side view showing the fit of the Magnum Air Power valve screws.

[FuzzyGrub]

John
I posted on the Disco upgrade thread also but will post here as well. I was not aware that there is a difference between the Disco and Maximus tubes that would prevent the Prod valve from working in the Disco tube. I was not aware that crosman had released the part list for the Maximus yet or did you have them send you one when you called to order parts.

I am interested in this conversion as well.

Mike

The maximus schematics were released a couple of weeks ago, but you can't see that kind of detail.  I was surprised that the air tube has separate part numbers based on caliber.   The difference only being the caliber is printed in small letters on one side.

[Rob M]

i keep looking at the rear breech screws wondering if and how that affects the hammer .. i see now , the screws need to go to the rear cap

[FuzzyGrub]

i keep looking at the rear breech screws wondering if and how that affects the hammer .. i see now , the screws need to go to the rear cap

Yes, you have to use the Prod end cap which is more squared off than the max/disco.  From looking at the syn stock, I'll have to take a bit off for that to fit.  The plus for max owners, you get a power adjuster with it.   

[Rob M]

makes sense, and skips the need to tap 2 new holes in the stock rear cap..

[RobertMcC]

Sounds close to my build. I bought a maximus. I got the 2400 PSI screws, using a Gmac 2240 multi shot breech. Only had to tap one hole to make it work. A aftermarket trigger.  Everybody like could have bought a Mrod for what you paid  to build you.

[FamilyMan811]

Sounds similar to what I did with the .177 LW 2300kt... worked out amazingly well. I did something similar with my frankendisco in .22 started In '15 as a boss valve beast 14 gr @ 1100 fps heavies were a hammer..and then  a prod valve attempt I botched lol ruined the valve..
Settled on mostly stock parts with a brass trigger and a few goodies. I have my .177 Maximus arriving tomorrow along with the Mrod trigger kit and those same valve screws you have... too "dang" much fun to tinker with

[KnifeMaker]

some of the pictures here did not' load. What would be the problem with drilling and tapping holes in the Maximus valve and tube for this conversion?

The Maximus already has the smaller dia. valve stem. So it can easily be made to flow better. Mine sure does!   A little valve work, gage block work, transfer port and barrel port work and polish, and she is getting up to 930 with JSB 18 gr. compared to 760 out of the Box.

Would love a repeater breach though.

Knife

[Buldawg76]

i keep looking at the rear breech screws wondering if and how that affects the hammer .. i see now , the screws need to go to the rear cap

Yes, you have to use the Prod end cap which is more squared off than the max/disco.  From looking at the syn stock, I'll have to take a bit off for that to fit.  The plus for max owners, you get a power adjuster with it. 

John
I have a Prod end cap on my Maximus now and the stock does not need to have clearance made for it to fit. It fits perfect and I have drilled out the small threads on the outer side and tapped them to the same threads that the adjuster uses so spring changes are a breeze and do not require the end cap removed.

Mike

[FuzzyGrub]

John
I have a Prod end cap on my Maximus now and the stock does not need to have clearance made for it to fit. It fits perfect and I have drilled out the small threads on the outer side and tapped them to the same threads that the adjuster uses so spring changes are a breeze and do not require the end cap removed.

Mike

Good to know.  I just did a visual, and hadn't laid the parts in the tube yet.

[imadunatic]

So, is it just the transfer port that is in the wrong spot for this to work in a disco tube? Or is it all the screws are in the wrong spot for this to work in a disco tube?

I've already fit a disco valve to my 2400, I'm thinking if all I need to do is drill the tube for the correct TP location, this is a fairly easy upgrade even for 22xx/disco owners with access to the right equipment. Even if they almost overlap, one could counterbore the valve slightly for a tubing transfer port (or teflon if you're so inclined).

I know someone will set me straight!!

Kevin

Edit: To clarify, I'm talking about fitting a PROD valve in a disco/22xx tube and fitting a PROD breach on top of it.

[FuzzyGrub]

Sounds close to my build. I bought a maximus. I got the 2400 PSI screws, using a Gmac 2240 multi shot breech. Only had to tap one hole to make it work. A aftermarket trigger.  Everybody like could have bought a Mrod for what you paid  to build you.

It looks like it must use some type of thimble (built in the block) to use the oem barrel.  If I was starting with a max, I'd have to cut and crown the barrel to get it in a manageable length shroud.   If there is no choke, that wouldn't be much of a problem.  As I mentioned earlier, not too fond of the mounting of the breech with only two screws, one very tiny.   If you are happy with it, that is all that matters. 

Gun builds do not have a positive roi. "Built" guns very seldom bring much money.  Almost always, need to return gun to stock and sell the mod pieces separately.   It is the enjoyment of doing and having something that not everyone has.  It might be more economical for someone starting from a prod and wants a rifle, but that is their decision.  I have fun and post the info such that others can use and decide what they would do. 

[FuzzyGrub]

So, is it just the transfer port that is in the wrong spot for this to work in a disco tube? Or is it all the screws are in the wrong spot for this to work in a disco tube?

I've already fit a disco valve to my 2400, I'm thinking if all I need to do is drill the tube for the correct TP location, this is a fairly easy upgrade even for 22xx/disco owners with access to the right equipment. Even if they almost overlap, one could counterbore the valve slightly for a tubing transfer port (or teflon if you're so inclined).

I know someone will set me straight!!

Kevin

Edit: To clarify, I'm talking about fitting a PROD valve in a disco/22xx tube and fitting a PROD breach on top of it.

The disco tp hole location is right where it needs to be for the breech.  It is the valve screw holes that don't align.  You would have to redo them in the valve or the tube or both.  Trying to drill holes in the tube that match the prod valve will be very close to the existing, and the bottom one is out.  Trying to drill new holes in the prod valve is no easy matter.  The current ones are at the back of the valve where there is more "meat".  Moving them forward means you can't drill too deep or will hit valve cavity or pocket.  You also need to machine a flat for each screw to get the right strength loading. 

Someone here on GTA has done it though, I believe they drilled new holes in the breech.  There is always a way, just different shades of difficulty.  For myself, if I had to use the disco tube, I would probably choose an aftermarket breech.

[imadunatic]

It definitely sounds like a mod better suited to the maximus than the disco/22xx for sure. Like you said, with the right tools/time/money anything can be done, whether one wants to undertake it is a completely different matter!

Thanks John. I'm gonna keep watching nonetheless.

[Matt15]

I am pretty sure a person could use secure a prod valve in a disco tube using the stock valve screw holes. You would just have to drill a new t-port in the tube. The Breech would sit a little bit forwards from the end of the tube.