.25 Crown maximum velocity

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I just had the hammer weight mod done by a tuner in the UK (AIRFECTIVE) and will chrono tomorrow, before the mod the 25g was pushing 940 @ 140 bar, 15mm on the gap but the 33 was way behind at circa 830.

Will see what difference the hammer weight mod makes @ 150 bar without doing anything else.

All I can say about firing the .30 cal Crown is boy is that thing loud!
 
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What slugs have a bc of .3 and .4? That is over 2x the BC of any projectile I have ever researched and would be interested...



150 bar is really high in REG PSI even for 500 mm barrels UNLESS you are aiming a tune in the 900's with 33.95's... I prefer to port closer to full bore when regulated and run a MUCH lower reg psi (135~) for more headroom and shot count. You really only need to exceed 140 bar when dealing with big bore and shortened barrels under 500 mm, or when attempting to shoot well over 1,000 FPS.



My 500mm Marauder barrel and "Power tune" does 33.95 = 900 fps @ 135 bar, tunable at 880~...at 150 bar it is 930 FPS, tunable at 920~.



The higher your reg pressure the more force holding your valve shut which requires more hammer strike to open. If you can make the same power with LESS reg psi, and LESS hammer strike, wouldn't you? There is no reason a 500mm barrel can't make a tunable 880 FPS @ 135 bar when ported 90% of bore. JMO...theres many ways to skin a cat, but this way is superior for the reasons I listed. Less hammer strike = less vibration inside rifle during shot cycle, and ease of cocking. Lower reg psi = more headroom for shot count. Larger ports = require less dwell. Absolutely zero negatives only positives when taking this approach...
 
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My power kits for the 25 and 30 cal crowns should arrive next week. In 30 cal I want to shoot the 51 gr JSBs at 880 - 900 fps. I already have my 25 set to shoot the 34 gr at 880 but it's on max. I want the adjustability to shoot them and the regular kings.
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I have a impact.30 700mm shooting 50.1gn 1005fps with 150b. The power kit available next year. 😎


 
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My power kits for the 25 and 30 cal crowns should arrive next week. In 30 cal I want to shoot the 51 gr JSBs at 880 - 900 fps. I already have my 25 set to shoot the 34 gr at 880 but it's on max. I want the adjustability to shoot them and the regular kings.
Click to expand...

I have a impact.30 700mm shooting 50.1gn 1005fps with 150b. The power kit available next year.
1f60e.svg


Click to expand...

I'm looking forward to it. I think my hammer is set too high on the 30 cal because it's highest velocity is on setting 3 -4 instead of 5 and max.
 
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That could be it. Though I recall (incorrectly maybe) that he had kits listed for sale.

blackdiesel

I'm looking forward to it. I think my hammer is set too high on the 30 cal because it's highest velocity is on setting 3 -4 instead of 5 and max.

What setting your power wheel falls for a particular tune is a function of the hammer spring pre-tension adjuster position. Better to be on 3 or 4 and have more tension available from the power wheel, than to be on Max and not have any room on the wheel to increase tension.

As an example, I removed all but a smidge of slack from my HS adjuste, per Ernest's video, as soon as I got the Crown so I would have highest hammer spring pre-tension available for increased power.

I recently ran some 21gr .22 caliber pellets over the chrono and got the most efficient performance at 140bar, TP/25-30, and PW on 5......898fps.

Now switching to 18gr .22 caliber pellets, I can get 900fps a few different ways. But I decided to do it at 130bar. At that reg pressure, I use TP/25-30, and PW on 2.

If I never wanted to tune again and I wanted the PW to show the Max setting instead of 2, I would have to reposition the hammer spring pre-tension adjuster (add slack) so the Max setting would give the same amount of hammer spring tension as it did on setting 2. 
 
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Agree with @bob_o, super easy and great customer service. Just call Newman at the FX_USA number above, and order the Power Kit for the Crown. Mine is a .22 caliber, and I want to shoot the 25.4 grain RD Monsters at a reasonable speed. With the 500mm barrel, I think the highest I will get is right in the 880 fps area, which should be good enough. I don't want to put a longer barrel on the gun, its long enough as is... ;) I'll be using the 500mm "B" liner in mine.
 
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You really only need to exceed 140 bar when dealing with big bore and shortened barrels under 500 mm, or when attempting to shoot well over 1,000 FPS.
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I try to learn something from everyone. But I have to tell of real world experiences from others, especially if they have given me advice that works.

I correspond with Matt Dubber and Roelf from Air Hunters. They are shooting 22 caliber FX rifles with 600 and 700mm barrels, shooting 23 to 26gr slugs between 920 and 950fps. Roelf has his reg set at 150bar, or maybe 155. They are obviously doing something right if their videos give any indication.

They have both given me advice that has been spot on. When I was tuning the Wildcat 25, I asked Matt what reg pressure to use for highest velocity and good stability, and he told me 150bar. What that gave me was 848fps avg with the 33.4gr pellet, ES of 6 and SD of 2. The rifle consistently shot around 1.5" at 100yds.

They wouldn't be running that high a reg pressure unless it was needed to get the performance they are getting. They are not shooting big bore, not going over 1,000fps, and not using short barrels.

So when I read something that says the opposite, it really makes me wonder. 
 
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What slugs have a bc of .3 and .4? That is over 2x the BC of any projectile I have ever researched and would be interested...



150 bar is really high in REG PSI even for 500 mm barrels UNLESS you are aiming a tune in the 900's with 33.95's... I prefer to port closer to full bore when regulated and run a MUCH lower reg psi (135~) for more headroom and shot count. You really only need to exceed 140 bar when dealing with big bore and shortened barrels under 500 mm, or when attempting to shoot well over 1,000 FPS.



My 500mm Marauder barrel and "Power tune" does 33.95 = 900 fps @ 135 bar, tunable at 880~...at 150 bar it is 930 FPS, tunable at 920~.



The higher your reg pressure the more force holding your valve shut which requires more hammer strike to open. If you can make the same power with LESS reg psi, and LESS hammer strike, wouldn't you? There is no reason a 500mm barrel can't make a tunable 880 FPS @ 135 bar when ported 90% of bore. JMO...theres many ways to skin a cat, but this way is superior for the reasons I listed. Less hammer strike = less vibration inside rifle during shot cycle, and ease of cocking. Lower reg psi = more headroom for shot count. Larger ports = require less dwell. Absolutely zero negatives only positives when taking this approach...
Click to expand...


This thread has nothing to do with tuning Marauders or any Crosman variant. There's many variables so to make blanket statements regarding tuning that's supposed to correspond with every airgun, every regulator, every plenum is a bit silly. I keep noticing this you don't need so much spring, you don't need so much hammer weight, you don't need so much reg pressure. I think you're trying to compare everything to your gun, it isn't a direct comparison. Do they have the identical plenum space? Is anything identical?
 
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What slugs have a bc of .3 and .4? That is over 2x the BC of any projectile I have ever researched and would be interested...



150 bar is really high in REG PSI even for 500 mm barrels UNLESS you are aiming a tune in the 900's with 33.95's... I prefer to port closer to full bore when regulated and run a MUCH lower reg psi (135~) for more headroom and shot count. You really only need to exceed 140 bar when dealing with big bore and shortened barrels under 500 mm, or when attempting to shoot well over 1,000 FPS.



My 500mm Marauder barrel and "Power tune" does 33.95 = 900 fps @ 135 bar, tunable at 880~...at 150 bar it is 930 FPS, tunable at 920~.



The higher your reg pressure the more force holding your valve shut which requires more hammer strike to open. If you can make the same power with LESS reg psi, and LESS hammer strike, wouldn't you? There is no reason a 500mm barrel can't make a tunable 880 FPS @ 135 bar when ported 90% of bore. JMO...theres many ways to skin a cat, but this way is superior for the reasons I listed. Less hammer strike = less vibration inside rifle during shot cycle, and ease of cocking. Lower reg psi = more headroom for shot count. Larger ports = require less dwell. Absolutely zero negatives only positives when taking this approach...
Click to expand...


This thread has nothing to do with tuning Marauders or any Crosman variant. There's many variables so to make blanket statements regarding tuning that's supposed to correspond with every airgun, every regulator, every plenum is a bit silly. I keep noticing this you don't need so much spring, you don't need so much hammer weight, you don't need so much reg pressure. I think you're trying to compare everything to your gun, it isn't a direct comparison. Do they have the identical plenum space? Is anything identical?
Click to expand...



The brand in my configuration has no merit or concern, the concerning factors are barrel length....if you want to hard focus on the fact I mentioned Marauder or Crossman, have at it...



I specify very clearly what my configuration is. If you think a brand is what determines energy output at the end of the day, so be it, I won't argue otherwise. 



I don't need much hammer spring because my hammer weight is balanced in such a way to produce enough hammer energy with less spring, in a fashion that doesn't over dwell the valve, and while running a SSG there is simply no concern for excessive hammer bounce...I believe there is no benefit to run overly sprung hammers and overly light hammers when there are IMO better ways to approach reducing hammer bounce...If you prefer a 20 + lb hammer spring and think they're the cats meow, your absolutely entitled to feel that way, I am not offended by it.



I don't need much reg pressure because I run much larger porting to compensate. 3 key factors can change fpe output (among many others) barrel length, reg pressure, and port size. Increasing any of these will potentially increase FPE output...so when I advise someone on a modification based on tried and true calculations, be it increasing port size, or even reducing reg pressure, then you can take it to the bank and cash it.



-Matt
 
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Haha no I don't think brand determines energy output, but to how a certain brand might get higher output may be different across brands is my point. No everyone wants to take a drill to their Impact or Crown to open up internal ports. (already probably sized for .30 anyways)

Long story short, probably takes a different method (higher reg pressure, more hammer weight) to tune a Crown or Impact for high power than it does a Crosman. I don't hate at all an Crosman or what have you, you have a cool gun and have done a great job with it Matt.
 
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I know a good chunk of the math behind how a pcp operates from valve strike to pellet hitting target, thats a LOT of information to gather / educate yourself on over time. Albeit, I still have tons to learn.. The knowledge I've obtained applies to all rifles regardless of brand...the biggest change between brand that may effect my calculation that many people won't know is volume from valve seat to base of pellet, or barrel tightness / choke...that can vary widely with some guns but even then that variable is marginal in the grand scheme of variables, which is caliber, barrel length, pressure, port size, plenum size (I pretty much always say provided you have enough plenum when regarding it), and pellet weight. Its not too complicated, believe me. The weight of the air from the discharge is also of importance. I can go on and on but the primary ones will always give similar outputs all being reasonably predictable. 

I don't suggest for anyone to take a drill to their rifle regardless if its 200$ or 2000$...anyone should know the risks when attempting modifications that require removal of material. I may however advise of a potential configuration or port size that will work for them that they can request from a tuner OR attempt on their own...we're all adults and can assume responsibility for our actions I hope



A 500mm barrel should perform near equally in an fx, crossman, kral, daystate, cricket, ect...provided everything else is equal or very close... pressure, plenum, caliber, pellet weight, port size...Now accuracy from said barrel, form factor of said gun, air capacity / volume of HPA changing shot counts is what really separates brand names at the end of the day. Anyone can spend a little coin and toss a 600-700" barrel on any brand .25" and blast 33.95's out at 1k fps provided they do proper modification at the end of the day.
 
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