Maximum power for .25 crown mk2

[Redwolfpaul25]

Hi all.

Just wondering with all thats available for tuning a fx crown mk2 ( tungsten hammer weight etc), what is a safe amount of power that it could be tuned to before any damage could occur due to excessive forces? I have found that 36.2g NSA slugs to be the most accurate at 875fps out of my .25 ( 65ftlbs) with a 600mm superior liner and reg pressure set to just under 150 bar. Could it be said that with my current barrel length, i am at my safe limit ?.

 

[Scotty1]

Do you have a slug kit in it? The FX slug kit consists of a pin probe, hammer weight and a modified shuttle.

 

[Redwolfpaul25]

Do you have a slug kit in it? The FX slug kit consists of a pin probe, hammer weight and a modified shuttle.

I have one but currently trying to see what things are like when the crown is stock and not fitted with the slug kit.

 

[MEC17670]

I'm shooting .25 cal. 29 gr NSA 250-HS-HP-DB, at 980 fps, with a 600mm barrel. Roughly 63.5 ft lbs. I have a Huma high range regulator set at 168 bar, power wheel at high, high end for this is 190, so I'm safe not to damage my reg, as long as I de-gas my gun prior to dropping my pressure, very important. I'm using a pin probe. My hammer is stock as is my hammer spring. My pre-load is max out on 20( custom power wheel) and depending on weather conditions, that power wheelmight have to be fine tuned before hunting. With a 700cc bottle , I get 63 full power shots .
These slugs and settings produce .355 inch groups at 57 yards. I do weigh and sort my slugs to 29 gr. plus or minus .1gr.
What kind of reg do you have? Depending on your brand of regulator, will depend on your "safety zone".
Remember the more stress on the other components due to higher reg settings , the more maintenance they will need.

 

[Jlowe]

Mine shoots 928 fps with 33.95 King Heavies or 65 foot pounds. I would assume you could get 70 foot pounds at 160 bar with the Tungsten hammer weight. All my FX airguns will do exactly what the factory says they will do.

 

[Redwolfpaul25]

I'm shooting .25 cal. 29 gr NSA 250-HS-HP-DB, at 980 fps, with a 600mm barrel. Roughly 63.5 ft lbs. I have a Huma high range regulator set at 168 bar, power wheel at high, high end for this is 190, so I'm safe not to damage my reg, as long as I de-gas my gun prior to dropping my pressure, very important. I'm using a pin probe. My hammer is stock as is my hammer spring. My pre-load is max out on 20( custom power wheel) and depending on weather conditions, that power wheelmight have to be fine tuned before hunting. With a 700cc bottle , I get 63 full power shots .
These slugs and settings produce .355 inch groups at 57 yards. I do weigh and sort my slugs to 29 gr. plus or minus .1gr.
What kind of reg do you have? Depending on your brand of regulator, will depend on your "safety zone".
Remember the more stress on the other components due to higher reg settings , the more maintenance they will need.

Thanks for your reply, everything on my crown is currently stock, i do have a slug power kit but took it out because i wanted tp see what i was getting accuracy wise ( and power)whilst the crown is stock standard. So far the only slugs that give me anything like the accuracy i require ( 0.5 inch at 50 yards) are the NSA 36.2g HS-HP-FB and the NSA 33.5g. My first port of call was to try lighter weight .25 slugs such as the fx hybrids but they shot like a shotgun, i have tried 30g prohunters,33g zans,28g H&Ns, 26g Fx hybrids, 29.5g NSAs but they had nothing like the accuracy i got from the heavier slugs. I would like my slugs to travel a bit faster but i do understand that velocity isnt everything.

 

[qball]

Stock crown max Reg is about 150, max out your hammer spring preload and find the knee to the power curve which is the max power stock Crown can provide based on your barrel length. At your current power level it is in factory Crown’s upper “comfort zoom”.

 

[Redwolfpaul25]

Stock crown max Reg is about 150, max out your hammer spring preload and find the knee to the power curve which is the max power stock Crown can provide based on your barrel length. At your current power level it is in factory Crown’s upper “comfort zoom”.

So on power setting 23 with the hammer spring tension nearly maxed out i am getting 900fps with the reg at 150bar, i think i may fit a gen 3 huma reg that a friend kindly gave me and see what i can get with a higher reg pressure, i was thinking 70ftlbs would be the crowns upper limit? I also have a few different weight hammer weights that i can try plus i have the high flow pin probe to try, my main worry was not putting to much strain on the rifle.

 

[qball]

Max reg as in max reg pressure the stock hammer can open. Get the power slug kit which has heavier hammer and you can go up to 180 bars, no need to buy huma reg unless you got money burning a hole in you pocket.

Max the hammer also means max out your hammer preload, not just the settings on the wheel. If you haven’t done so then you most likely have not maxed out the stock crown power.

For reference my crown with reg at 170ish using power slug kit can get over 80 FPE with 700mm barrel. Obviously it uses a lot of air at that power level.

 

[Chukar60]

Just to reinforce the data. My 600mm Crown MKII 25 is tapped out at 145 bar and the hammer just shy of maxed out. It shoots 34 gr H&N slugs right @ 900 fps. 26.8 gr NSA were doing high 930’s.
I have no idea as to why but when I asked UA about the slug kit they seemed luke warm about the idea.
Be nice if I understood their pensive take on it with a Crown.

 

[Chukar60]

Max reg as in max reg pressure the stock hammer can open. Get the power slug kit which has heavier hammer and you can go up to 180 bars, no need to buy huma reg unless you got money burning a hole in you pocket.

Max the hammer also means max out your hammer preload, not just the settings on the wheel. If you haven’t done so then you most likely have not maxed out the stock crown power.

For reference my crown with reg at 170ish using power slug kit can get over 80 FPE with 700mm barrel. Obviously it uses a lot of air at that power level.

Referring back to my post, have you seen or are aware of any downside to the slug power kit other than air usage?

 

[Redwolfpaul25]

Max reg as in max reg pressure the stock hammer can open. Get the power slug kit which has heavier hammer and you can go up to 180 bars, no need to buy huma reg unless you got money burning a hole in you pocket.

Max the hammer also means max out your hammer preload, not just the settings on the wheel. If you haven’t done so then you most likely have not maxed out the stock crown power.

For reference my crown with reg at 170ish using power slug kit can get over 80 FPE with 700mm barrel. Obviously it uses a lot of air at that power level.

Yes i have physically maxed out the hammer preload to the point that the power wheel wont turn so i backed it off the hammer spring grub screw a bit.

 

[qball]

Referring back to my post, have you seen or are aware of any downside to the slug power kit other than air usage?

My reg is at 165-170ish bars and have gone through probably 1500 shots and no issues so far.

The other noticeable "downside" of cranking up the power is the recoil much more prevalent or noticeable but that's a given. Keep in mind the slug power kit hammer is MUCH heavier and you should not turn your reg down below 150 bars. Also if you want max power go to 700mm barrel.

 

[Chukar60]

My reg is at 165-170ish bars and have gone through probably 1500 shots and no issues so far.

The other noticeable "downside" of cranking up the power is the recoil much more prevalent or noticeable but that's a given. Keep in mind the slug power kit hammer is MUCH heavier and you should not turn your reg down below 150 bars. Also if you want max power go to 700mm barrel.

I am battling between making the 600 work because I don’t care for the length that comes with a Crown or selling it and getting another M3 in 25. Just not too sure which way to go at this time.
Thank you for the reply.

 

[qball]

I am battling between making the 600 work because I don’t care for the length that comes with a Crown or selling it and getting another M3 in 25. Just not too sure which way to go at this time.
Thank you for the reply.

600mm will work, just keep in mind that it won't have the same speed as 700mm. I was shooting 35 grain slugs @ 70FPE with 600mm barre in .22, it was no slouch. In 25 you should be able to get to 80 FPE with some tuning.

 

[Jlowe]

600mm will work, just keep in mind that it won't have the same speed as 700mm. I was shooting 35 grain slugs @ 70FPE with 600mm barre in .22, it was no slouch. In 25 you should be able to get to 80 FPE with some tuning.

Excellent information. Excellent contribution of first hand knowledge.