A 25 Cal Fortitude

[anti-squirrel]

Impressive work, John

I love seeing crafty engineering performed by means of commonplace tools, patience, and a good set of steady hands.

Probably saved more than a few dollars, too

[FuzzyGrub]

Impressive work, John

I love seeing crafty engineering performed by means of commonplace tools, patience, and a good set of steady hands.

Probably saved more than a few dollars, too

Thx.

This project has been going well, so far.  The one advantage to crosman is, easy access to replacement parts when you mess one up. 

If it wasn't a hobby and counted my time, probably one of the more expensive mags out there.  ;0 

[FuzzyGrub]

I discussed with Rod (GTA member rsmn), the possibilities of a single shot tray.  That is looking promising.  He has been able to quickly make custom ones for me, such as a 177 prod one.  He is very good to work with and highly recommend him.   

So, I'm probably going to make one more mag and not send it out in the future for machining.  The machining would make it convenient for mag replacement in the future, though.  vs spending a couple hours modifying one, now that I know how to do it.  My experience with the crosman mags, is mostly they just need cleaning and readjusting the screw.  sometimes the spring. 

[FuzzyGrub]

Getting a little bit of time today:

- Adjusted reg to higher pressure, hopefully close to 2Kpsi (still awaiting plenum)
- Opened valve exhaust to 0.187"
- Opened poppet pocket to 0.230"
- Main valve body is 0.560" ID, nothing left to get there
- Installed Mrod/Prod poppet
- Found a conical spring that should work, but need to mod retaining washer or make new one.  The opening in the retainer is only 1/4" OD, so want to go to 3/8"

[FuzzyGrub]

The plenum finally arrived today.  See below for the latest stack up of parts to go back in the tube.  Still need the gauge to see the set-point, but will be able to see if I can hit the 40fpe mark, before pulling the gauge back out.

Rod has shipped out the semi-custom shot tray and should have that by the end of the week. 

[mackeral5]

The plenum finally arrived today.  See below for the latest stack up of parts to go back in the tube.  Still need the gauge to see the set-point, but will be able to see if I can hit the 40fpe mark, before pulling the gauge back out.

Rod has shipped out the semi-custom shot tray and should have that by the end of the week.

That is a whole lot of plenum!!!! 

[FuzzyGrub]

It looks like I'm in the ballpark.    One half turn on the reg adjustment does equal 500 psi.  It was right at the 2k psi per fill gauge. 

I got 16 shots at and just under my power range, but in my haste to make a TP, it is leaking. 

Mag is cycling fine. 

[mackeral5]

Your plan is coming together nicely. 

[FuzzyGrub]

Your plan is coming together nicely.

Thx.  I am missing a 25 cal shroud mount, so will need to put in a order with crosman.  Need to go thru a list of Mrod 22 parts, to see what is needed to complete that gun. 

I need to pick up some modeling clay so I can figure out the right TP length. 

[FuzzyGrub]

Received the SS tray from Rod.  Fit tight, works nice. 

[mackeral5]

Looks good.  I like the high vis orange, should make it harder to lose trays.

[FuzzyGrub]

Looks good.  I like the high vis orange, should make it harder to lose trays.

I generally only use them for testing, and mainly on the indoor range.  The orange allows me to easily see that it is installed in the gun and gives good visibility of the pellet when in the channel.  Rod does have multiple color choices. 

[mackeral5]

I must admit I really haven't paid much attention to the Fortitude---I don't have a need for yet another 7/8 tube, long rifle in my airsenal.  So I have intentionally not paid much attention.  Yesterday I finally watched Southern Gunner's lengthy review and now I understand the attraction.  It is magazine fed and it is LIGHT!!!  Plus being a crosman spare parts, mod parts, modding methods are known and readily available. 

You've created an ultralight, MAGAZINE FED,  rifle with Mrod like power.  I get it now.  15+ shots of 40fpe out of a very lightweight package.   it is almost screaming for a double tube kit---if it wouldn't take away from the gun's best quality of being lightweight. 

I have my own version in QB78 form that I may drop a .25 upper on if only to test.  It is the SS Cothran tubed gun in my profile pic.  It is set up with an in tube Huma.

[FuzzyGrub]

I understand the attraction.  It is magazine fed and it is LIGHT!!!  Plus being a crosman spare parts, mod parts, modding methods are known and readily available. 

You got it! 

I actually built very similar guns prior to release of Fortitude.  A good number of years ago, built one with a custom air tube from MM.  And before the Fortitude was announced, built one from a Maximus tube.  That one looks so close to the Fortitude, I'd swear they got the idea from me.   

Actually, for a 177 or 22 I'd wish the were 4" shorter, ie carbine length. 

[subscriber]

Actually, for a 177 or 22 I'd wish the were 4" shorter, ie carbine length.

40" overall would be perfect!

[mackeral5]

John, I have a huma plenum question. 

I need a plenum for my qb78 double.  It needs to have an outside oring on one end, a face/flange oring on the other.  Without a gauge hole.  Prod/disco diameter.

Do you know which plenum to order? Thanks in advance.

[FuzzyGrub]

John, I have a huma plenum question. 

I need a plenum for my qb78 double.  It needs to have an outside oring on one end, a face/flange oring on the other.  Without a gauge hole.  Prod/disco diameter.

Do you know which plenum to order? Thanks in advance.

All of the Huma plenums for Prod, Maximus, and Disco, have face seals on both ends.  None have provisions for a gauge or the outer o-ring like on a gauge block.  They seal against the valve or gauge block.  The disco one sitting on my bench, also states it fits Artemis PR900W / Diana Stormrider.  I suspect that huma does not sell one in that diameter that does what you want.   

[FuzzyGrub]

I have been working on a better sealing TP: https://www.gatewaytoairguns.org/GTA/index.php?topic=153928.0

[FuzzyGrub]

I did a test string with the new TP.  Now getting 16 shots at average of 882fps.  The poly TP must have been leaking more than I thought. 

Also, this was the first time shooting the 25 cal with the shroud back on.  Nice and quiet.   

[mackeral5]

I did a test string with the new TP.  Now getting 16 shots at average of 882fps.  The poly TP must have been leaking more than I thought. 

Also, this was the first time shooting the 25 cal with the shroud back on.  Nice and quiet. 

You exceeded your goal by just a bit, great job. 

Thanks for the info on plenum extensions. 

Do you know the lengths of the Prod and Disco extensions?  I could make one work by inserting a Prod gauge port on the valve end, with only one oring, towards the valve.  the issue is I currently don't have anything for a face/flange type oring to seal against.  The gauge port would provide that.