Power Tuning Mods for the FX Crown

Hi atom,

Did you ever try that Altaros regulator plenum mod idead? How did it go? I am trying to boost power on my .25 and it would be nice if that works.

You could mount the pressure regulator that is used for the FX Royale400 / FX Boss and mount the additional 14 cc pre-chamber, always sold by Altaros. From what I read on the Altaros site, the regulator is fine for standard tank with thread M 18x1.5.

Does the crown tank have this thread?

However, it is necessary to know if the regulator is screwing on the crown castle. Adjuster and additional pre-chamber have a measurement of 9.6 centimeters, this makes the crown aesthetically ugly, but if it does not affect aesthetics, perhaps the work can be done and the power should increase.

It would be necessary to write an email to Altaros and ask for his advice.

Another problem could be that the reading of the 2 Crown gauges are no longer exact and the tank must be refilled by the connector on the Altaros regulator.

Mahhhhh !!!!!

https://www.altaros.cz/en/airforce/107-extra-airchamber-for-high-power.html



https://www.altaros.cz/en/fx-airguns/16-4820-fx-airgun-royale-400-fx-boss.html

I think that you would take the high pressure gauge out of the Crown and plug it because you would have a gauge on the bottle regulator. Then the issue would be that you would have essentially a large low pressure plenum on the old high pressure side, so you would need to connect those two plenums into one large one. You would have to take out the old regulator and plug the hole, or possibly put a cylinder style plenum in there..., and then you would have to ensure that you have one continuous plenum. Yes, I do believe the threads are correct, although you may need a male to male adapter.

Hi mtnGhost,

Thank you very much for putting this guide together. I am just now starting to put some power mods to my Crown Continuum .25 and this is my bible for now.

I am wondering if you might be able to tell me what is the max length hammer weight can be without cutting the spring guide back? I have a 7gm brass hammer, I think it is the Rowe type. Will those fit without cutting the guide?

I would like to hit around 80 FPE. This weight might not take me that far, but I am keep to see what I can get out of it.

Thank you for the advice and this great guide!

I am about to start modding on a .177 Crown and would like to hear some thoughts from the been there done that crowd.



Reg is currently at 110 bar and am running JSB Monsters right under 20 Ft Lbs.

With doing the transfer port and probe mods, will a larger valve seat provide any benefit in .177 or would there be no real gain in the smaller caliber?

Problem with small caliber is its not really all that efficient to begin with. So, it's more difficult to extract power. There would, of course, be benefits to port, hammer, and probe work. But I recon you're already shooting Pellets plenty fast. So, you'd want to use slugs instead to extract that extra power without breaking the sound barrier.

However, I cannot see that a larger valve seat would yield any benefit at all. Your valve seat is already over-sized (5.5mm)

I kinda figured that was the case, going off of the current thoughts on Impact mods for calibers less than .25. Just looking for confirmation that my suspicions were correct.



Slugs are the plan, unless they don't shoot worth a poo pile, then it will be back to the JSB heavies.



Thanks for the input.

I finally ordered the pieces necessary for the customization of my crown. 25.

- Hammer of the FX boss.

- VS original in steel (I will enlarge the hole makes 5.5 mm to 6.2 / 6.3 mm).

- spring holder (to be modified according to the length of the hammer) .... Pieces ordered by the UK.

From Huma I ordered High flow dual hole transfer.

As soon as the pieces arrive I will get to work and tell you that power and autonomy I will be able to "squeeze" from the crown.

For now, thank you all for your valuable information.

Just wanted to give an update on my testing of the Huma TP.

First thing was to get my modded factory ones off. Getting the inner oring out was a little tricky. I didn’t have a dental pick so I made a little custom pick.


I tried to heat the TP with a heat gun but it wasn’t quite hot enough so I gently heated with a propane torch until just a little smoke came off and then a leather wrapped vice grips did the trick. FX used an awful lot of loc tite. 
Here’s a pic of my modded probe in the Huma TP. It appears there may be a few fps hiding in the corners, but for most part it appears to line up pretty well. I wish I had a stock probe to check.

.

I recently tuned the gun back to full power. With the reg at 152-155 bar I fired up the FX Chrony. Here are the results.





The Huma TP came very close to my modded TP and I think there is room for improvement on the Huma. I did notice that pushing pellets through the Huma felt quite rough. I didn’t check accuracy yet . I may push a few pellets through the TP and see what they look like. It may need a little polishing.

Next up I’ll be installing the larger valve seat. So far I’m pretty impressed with just TP and probe were nearing 70 ft/lbs in 700mm and I can put on the 380mm and dial down to PW3 and stack 25.4’s at 50yds at 865fps.

Just wanted to give an update on my testing of the Huma TP.

First thing was to get my modded factory ones off. Getting the inner oring out was a little tricky. I didn’t have a dental pick so I made a little custom pick.

I tried to heat the TP with a heat gun but it wasn’t quite hot enough so I gently heated with a propane torch until just a little smoke came off and then a leather wrapped vice grips did the trick. FX used an awful lot of loc tite. 
Here’s a pic of my modded probe in the Huma TP. It appears there may be a few fps hiding in the corners, but for most part it appears to line up pretty well. I wish I had a stock probe to check.

.

I recently tuned the gun back to full power. With the reg at 152-155 bar I fired up the FX Chrony. Here are the results.

The Huma TP came very close to my modded TP and I think there is room for improvement on the Huma. I did notice that pushing pellets through the Huma felt quite rough. I didn’t check accuracy yet . I may push a few pellets through the TP and see what they look like. It may need a little polishing.

Next up I’ll be installing the larger valve seat. So far I’m pretty impressed with just TP and probe were nearing 70 ft/lbs in 700mm and I can put on the 380mm and dial down to PW3 and stack 25.4’s at 50yds at 865fps.

Click to expand...

@srtmat

hello friend good contribution.

did you make a modification to your transfer port? or did you just put the one you bought from huma?
I am waiting for one to buy, hopefully it will arrive this week I have heard that sometimes they have problems introducing the pellets, I hope this is not the case.

and regarding the pellet probe? What was the best option?

Thank you

Hi srtmat,

It is good to see another person with a .25 Continuum going through the same process as myself.

I just got the Huma TP in as well and have installed it. I found maybe a 20 FPS improvement. I also am using a heavier hammer, about 7 grams. Are you using a modded hammer or any other mods at this time?

What is the measurement for your adjustment screw? Mine is around 16mm using the weight. I am set at 160 bar and getting 60-65 FPE depending upon the type of ammo I am using. With the 34 grain jsb heavies I am shooting at around 930 fps. It looks like you are actually getting more power out but at a lower reg setting, so I am wondering what I might learn from your settings, to see if I can improve mine.

By the way, I also find that the Huma TP hangs up when you are loading ammo. I also feel that the Huma TP could benefit from a bit of rounding of edges and possibly contouring to help air flow.

I have not yet installed a larger VS, but will do so soon.

I also ordered a TP Huma 10 days ago, but it hasn't arrived yet. I read that there are domed problems that don't go well .... I hope it doesn't happen in all their TPs. But to polish the inside of the TP, which product are you going to use? Fine abrasive paste?

I noticed that the mod to the original TP makes 10 fps more than the TP Huma .... as you have suggested, widening or lengthening the double hole by 1 millimeter and flaring it slightly, you could get the same fts.



A question about the hammer .... How high is the flange of your hammer? The flange of the hammer that I bought, that of the FX boss, is 10 millimeters high, certainly too many, as they preload too much the spring that pushes the hammer.

Hi Libellule1,

I do think that rounding out some of the edges of the Huma TP might help with the issues of pellets sticking. I also think that it might help with FPS, because it could improve the laminar flow of air into the barrel. I am not sure about lengthening the holes, if pellets are already sticking, but perhaps just rounding those transitions. It may be beneficial to widen the holes a bit and to of course round the corners out.

I am not sure about my hammer flange but it is certainly nowhere near 10mm. I would say that it may be 4mm, max. It is installed in the gun now and I do not plan to take it out to measure it, but I am certain that it is nowhere near 10mm. I think the issue of preload can be resolved by shortening your set screw, so you should be ok.

Yes, you are right, better not to stretch the double hole of the TP Huma. Better to remove the corners, hoping that the ammunition will no longer come in with difficulty.

The one in the photo is Ermest Rowe's hammer.

Rowe's brass hammer has a flange at most 3 or 4 mm high, like yours .... I will work my hammer in order to obtain a weight of about 7 gr and a flange not more than 4 mm high. Thanks for the valuable information you gave me.

@dani357k - Yes I modified the factory TP’s on my 380 & 700mm barrels. The Huma I tested was completely stock. I followed the instructions from the Impact guys modding them in this thread. 
https://www.airgunnation.com/topic/fx-impact-mods-for-more-fpe/

My pellet probe was actually referenced here on page 3. mtnGhost said he had accuracy issues with this design. While I don’t doubt his findings mine has preformed flawlessly and I’ve found no accuracy issues. 

I think some people had loading issues if they cut too much off. I left the tabs/ears shown by the arrow. I also did quite a bit of thinning on the inside diameter to create a larger opening for more exposed surface area behind the pellet. My TP’s were slightly elongated and then tapered in on the inside towards the back of the pellet.


@RabbitBlaster

I'm not sure how you are measuring your hammer spring screw adjustment but from that number I’m guessing your using the same method as I do. I keep track of my adjustments by measuring like this.



I am using the stock hammer. I think the heavier hammer weight would be beneficial if I was running above 155bar reg pressure but under that the stock hammer seems to open the valve just fine.
My plan was to get the most I can on stock hammer. I’m worried a heavier hammer will degrade the shot cycle some when I have the 380 barrel on and PW dialed back to 3. I also don’t want to lose shot count by having the gun cranked up to 160-165bar. I’m looking for that sweet spot to get the most out of the 700 but not ruin the 380 setup where this gun spends most of it’s time.

I hope to pick up a few more fps with the VS but if not I’m still very happy with the current power and should be able to take advantage of a few more slug options with the 50fps I’ve gained so far.

I tested pushing pellets through the Huma TP by hand and I’m happy to report the pellets look just fine. From what I can tell the resistance/roughness I perceive is only from the pellet pushing through the inner oring. I even put a few through from the opposite end and they drop right passed all the porting/machining with no resistance and stop right at the oring with the skirt completely past the porting.

My thoughts are 1. Maybe they use NBR 90 instead of 70 like factory. 2. Just needs some time to break the oring in a little. (I’m comparing the feel to my well worn factory orings.) 3. Maybe there oring groove is not machined quite as deep.

again all just speculating but at least it doesn’t appear to be damaging the pellets. Accuracy testing will have to be done to confirm. I will still probably do some smoothing with the dremel for better flow.

A question to those who made this mod ..... a PIN pellet pusher, how much longer than the original pellet pusher must be built? 1 or 2 mm more are right, or you risk having a pellet pusher too long and not being able to put the loader anymore.

I'll not be replacing the VS.

I have since installed a hammer weight and turned the reg. up to 170. Got to 960 fps. Then the hammer spring adjuster screw stripped out! I've re-tapped the block to 6-32, but don't have a long enough screw to test it yet.

Super high power isn't going to work out for my Crown...

Click to expand...

So I decided to go ahead and see how much power I could get with the dual port and hammer weight installed. With the hammer spring adjuster retapped the full length to 6-32 I figured it was safe to try full'er' power. With the AMP reg at 170, maybe a little less, I was able to get JSB .22 25.4gr pellets to 992fps. 55 ft/lb!

Decent groups at 100 yards. Switchy winds so it was hard to tell what was going on. Nice little knots at 75 yards.

Kicks like a light .22 rimefire now. Recoil management is going to be a factor if I stay at this power level.

It is also so nice to have the Boss trigger installed!!!

Now to try some slugs...

@BSJ Nicely done! I decided to re-work one of my dual port TPs, so I opened it up a bit and rounded out the transitions and I also turned my probe into a double hole but I also took out the ring at the end and just left two vertical walls. Seems it gained me about 5 more FPE. I am now shooting .25 cal 33.95 gr heavies at 960 FPS and 69.5 FPE.

I still have a little bit of grinding to do and I am still waiting for my 6.3 mm valve seat. I am looking forward to seeing what I get when I install that!

Nice numbers. Can’t wait to see how the VS goes. I’ve got my VS sitting here but it’s going to be a week or so before I can put it in.