There is nothing indexing the bolt in these. It's very conceivable that the front delrin portion might spin slightly after a couple thousand cycles. Even with all the mods, the re-cock becomes extremely unreliable if you have a single ball break in a cat, so "shooting through" a chop isn't really an option anyway. At any rate, last time I tried shooting 0.675 paint through a cat, I never made it out of the staging area. Today I put at least 4 or 5 hoppers though it. The whole point of this is to make sure there AREN'T any loose shells in the breech....
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I use Tapatalk which does NOT display comments. If you want me to see it, make it a post not a comment.
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https://www.mcarterbrown.com/forum/b...323-s-feedbackComment
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*Notices Myrkul's new mods*
*Takes notes*Comment
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I wonder if a T15 bolt would fit in a Cat. I know it's based on the design. Obviously the slider doohickey would have to be swapped for the donut.Attached FilesComment
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Great mod. Put about half a case through my thundercat at bones n' ashes a couple weeks ago by modding my bolt in this fashion.Comment
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2026 Update: Finally found a NOS Pro-Line cat trigger.
Back in the day me and my brother used to run Pro-Line Triggers on these and they were fantastic....except the sharp edge on the bottom of the trigger plate would eventually punch through the shoe and render the Proline trigger plates inoperable (Which is why I switched back to the stock ICD triggers many years ago despite preferring the ergonomics of the Pro-Line triggers).
Long after our Pro-Line triggers were finished, I discovered this resource for the ICD desert fox:
ICD 98 Desert Fox Tweaks and Accessories
Which posts up the solution: Knock the sharp edge off the bottom of the cat trigger plate to prevent it from digging into the shoe.
Needless to say, now that I had a solution I've been keeping an eye out for any pro-line cat triggers for quite a while, but unfortunately every single one I've come across was starting to fail exactly like the above picture.
Recently, Reflex0283 shot me a tip that there was a NOS one on ebay, so I had to snag it!
A few minutes with a Dremel and some sandpaper, and that sharp corner was rapidly delt with:
And the Pro-Line trigger is now installed and happy on this gun, and minus the mods and freak barrel, its set up just how we used to run them in highschool!
Very excited to get this out on the field again soon.
Last edited by Myrkul; 08-03-2026, 03:59 PM.Comment
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Ran the thunder cat for about half the day at splattag's giant game. It performed flawless even with the fragile tournament paint that was causing most players issues.
Last edited by Myrkul; 09-20-2026, 03:37 PM.Comment
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Bob Cat Differences.
Finally got around to getting my Bob Cat running on HPA. This was definitely a little trickier to do then my Alley Cat or Thunder Cat since the volume is a lot more restricted on these.
Step 1 is to drill out the air passage on the Vert ASA AND on the body itself. The largest I was comfortable going remained 7/32.
Step 2 is actually replace the main spring with one from a later model cat. It looks like the Alley Cat/Thunder Cat main springs are about 1/8" longer. I used a fresh one from those 32 degrees kits that occasionally pop up on Ebay.
Step 3 is to Polish up the valve Stem.
I usually disassemble the valve stem from the cup seal, toss it in a drill chuck, and then hit it with sand paper. 600, 800, 1,000, 1,200, 1,500, 2,000, 2,500, 3,000 grit sand paper. I also hit the brass edges around the cup seal itself.
Step 4 is to sand the cup seal flush. I noticed on a lot of cats, especially if you are using a replacement cupseal, the cup seal sticks up a bit above the brass cup seal base. This causes the valve stem to sit a bit lower then it should and decreases the velocity. Using a plexiglass backer, I sanded it in a figure 8 motion to ensure it stays perfectly flat. Again, I use 600, 800, 1,000, 1,200, 1,500, 2,000, 2,500, 3,000. grit sand paper. I usually keep going until the cup seal is just below flush with the brass edge (this does knock just a little bit off the brass edge too).
I have gone back and updated both my Thunder Cat and my Alley Cat with this valve polishing/tuning as well, and both experienced a significant velocity increase, which I then used to decrease the tension on the main spring for a softer shot. Be sure to use blue Loctite on the threads when reassembling!
Step 5 is modding the bolt. I managed to bevel the bolt tip in the Bob Cat, but the bolt face is a little different then it is on the Thunder Cat and Alley Cat so I had to be extra careful not to take off too much material. For whatever reason, my Bob Cat refused to beat the nylon washers into the correct diameter like my Thunder cat did. After I got the inner diameter hogged out with the Dremel, I had to toss those washers in the drill check and sand the outside diameter down so that the black plastic donut could slide freely over those like it was supposed to.
And that's about it. I took it to the chrono today and was able to get it cycling perfectly in the 290 range with extremely small field paint and a large overbore. Put an entire hopper through it with zero issues.
I suspect that these additional mods will work on getting a Puma up to speed as well, but I don't have one handy to act as a guinea pig.
10/04/2026 dumped a case though the Bob Cat at the big game today. Zero barrel breaks or misfires. This thing shoots absolute fantastic. I brought other markers to use, but at the halfway point I put everything else in the car and just kept running the cat.
Last edited by Myrkul; 10-06-2026, 02:14 AM.Comment
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I recently got my first cat, an Alleycat, and the first thing I did was to port the inlet with a 3/16" drill. Happy I stumbled across this before I try with small field paint!Feedback
www.PhrameworkDesigns.com < Nelspot, Sterling, and Phantom parts, plus the occasional big project.Comment
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