Power Tuning Mods for the FX Crown

Picking up this “old” topic. Yep, might be old; but then again -as someone already so rightly put it- there's not that many topics to be found on Crown modification ...


On reading the following ...

I am in New Zealand and anything I order takes ages and nothing is available in country...

Pat,
Just been wondering...
If indeed the wait for ordered goods appears that long,
why not try and make your own hammer weights in different shapes, sizes and weights.

I ve done so, tinkering away with some stainless steel bolts to start from.


Stainless steel bolt.1631538982.jpg




Not at all being technically schooled whatsoever, all i used were some basic tools like angle grinder, a heavy drill with adjustable speed (fixed to a workmate table), 2 files with different grit, some sandpaper sheets of various grit size, and of course a digital calipers.



So far i ve made 4 stainless steel hammer weights, respectively 7 gram, 9,5 gram, 11 gram and 12 gram.

I m still to make 2 additional hammer weights, but this time in brass. But i m still to visit the hardware store to acquire the appropriate brass bolts with various head hights i ve ordered there.



brass bolt.1631539005.jpg




Been considering brass to be better suited for the purpose (i think), since its volumetric mass density is somewhat higher than the specific mass of stainless steel.



In the meanwhile i had last week ordered some pin probes and some V2 dual hole transfer ports (in 2 calibers), together with still another tuning hammer spring, with the guys from Huma. As soon as my 2 brass weights (with different head hights) get finished, i ll start combined testing the 6 available hammer weights on the 4 different springs i ve collected (somewhat varying lengths, different coil numbers and coil diameters, but all springs with the same OD).


Mine is a MKII Crown (with 6,5mm valve seat plus somewhat larger plenum) and i m curious to discover how "low" the reg pressure can be kept to shoot JSB Redesigned Monster pellets up to 32.4 grain Eunjin pellets. As well as every .22 slug up to 40 grain i can get my hands on, both aiming at +950fps velocities as well as all the time aiming at the best efficiency in air consumption.



Hoping to hear some more news of the earlier particpants in this topic.


 
Hi Ex.Magnum, 

Good idea with the bolts! I may try that myself. I think the heaviest hammer weight I have is about 9gr., but I would like to try heavier ones as well.

I have the Huma twin port and I just got the pin probe, but have not tried it yet. I also got the tuning spring from Huma to give a try.

I have so far managed to get 80 FPE out of my gun, a Mark 1 Crown Continuum. I am hoping to have a larger plenum made for it so I can do that on lower reg pressure.

Let us know how you go!
 
No photos or sketches are shown of the pellet probe mod, except from RabbitBlaster, which seems rather drastic.(oops, I didn't see all the posts on the other 7 pages of this thread) I squared the hole off on mine with a file and installed the dual port TP. One probe mod seen here has opposing holes. Since the air flows in from one side, what advantage is there with the second hole?? Isn't there a pin probe available? Seems that would be the best thing. Running my reg at 165 bar.
 
Huh. A bit dated now, but if anyone wants to port an older barrel... I noticed I never put up the port work I did to my gun in this thread. Probe also cut to match.

General Idea being based off of a power increase I noticed on my .22 when turning to the larger .30 port setting on the port wheel.

I made a bellmouth with the outer diameter matching the tranfer port @ .30" Left the middle of the port un-touched. And radiused the inside of the port toward the barrel/projectile, also elongating the port there, and cutting the probe to match. Gains were 50fps and 75fps over factory maximum on 380mm and 700mm .22 barrels, respectively. Putting me at 930fps with 18.13gr pellets in the short barrel.

Should be noted that smoothing/polishing the newly cut/ground port profile caused a loss in power. The finish of the port is better left in a some-what rough state to aid laminar flow 

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Isn't there a pin probe available? Seems that would be the best thing.



I agree, Paul.
Pin probe is the best way to go (imo anyway) for anyone who doubts whether they can confidently achieve an absolutely perfected cut-out of the factory probe, entirely and completely matching the barrel inlet air-dynamics. If not, then incoming air stream is bound not to be any longer 100% optimal, resulting in some degree of "swirling" possibly mortgaging flow. 
That mere consideration has lead me not to start hand-dremeling stock probes, but immediately insert pin probe substitutes. At the same time also leaving me the option to -at any given point in time- go back to stock with my original probes intact, if ever i want to.

Isn't there a pin probe available?

Since recently, Huma has the pin probes available for Crown in .22, .25, .30 . 
However, Huma does not yet offer the .177 version. So I asked Marc (of Huma) to also make me a .177 pin probe (starting from a .22 one). And he immediately did so. 

P1050559.1631931010.JPG


I m now shooting all of my Crown calibers on pin probes (with V2 Dual tp's combined).
I have not yet encountered any disadvantage. On the contrary.
Especially the pin probe in .22 cal delivers a massive surplus efficiency compared to stock probe. (when combined used with V2 Dual)

For those .177 Crown shooters with a keen interest :
Within short term .177 pin probes will also be continuously availabe on the Huma webshop (as Marc told me). But i m sure if anyone right-away-today were to ask him to make a .177 pin probe , he will accomodate that person immediately. (like he did for me)