Thanks for the post. Excellent test and pics. I always like reading these types of experiments. Nice shooting BTW.
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FX Crown barrel band. Unnecessary, yet necessary... (New)
- Thread starter JoeKool
- Start date
Good question. No sir, the/my Dreamline needs the barrel support. I have tested and proven this. For the first year of owning my DreamPup I chased a wandering POI. At first I thought it was many other things, like a bad STX liner and a few other things. Once I discovered it was the flexing free floating barrel that was the cause of POI shift. Well, I installed a good quality barrel support band and its been laser accurate ever since!
Dreamline barrel band = Stay
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From a scientific point of view, if the gun was tuned for accuracy without barrel band, it might be less accurate with it on, as the harmonic behavior change. And probably vice versa. Extending the shroud on different length might have the same result. But a nice test
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From a scientific point of view, if the gun was tuned for accuracy without barrel band, it might be less accurate with it on, as the harmonic behavior change. And probably vice versa. Extending the shroud on different length might have the same result. But a nice test
I agree with that.
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Curious - any idea why the Dreamline barrel is more flexy than the Crown? The Dreamline Classic (.177) is one of a few guns on my list for a new field target gun but the “droop” reports I see kind of make me wonder about it.
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The flex is because of the lack of rigidity of the blued barrel sleeve that the STX liner goes into, and the shallow threads of the coupler piece it screws onto (the lack of solid barrel support). It’s just not as strong and rigid as the solid steel smooth twist barrels where in the Dreamline’s predecessor the Streamline. It is usable but tends to droop and can clank against the air cylinder. I own a Dreamline Classic in .177 (I love the gun) and it is a tack driver, but I’ve installed barrel supports. The FX Crown doesn’t seem to have this problem, could be that the barrel goes deeper into the breech block or maybe the design of the shroud.
Check this thread?
https://www.airgunnation.com/topic/dreamline-classic-177-vs-dreampup-22-25-and-50-yards/
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I wanted to add to the info provided above. I bought the same barrel band and fitted it on my .25 cal Crown. Fitment is perfect.
If you like to rest your gun on the bottle for bench shooting, understand that your POI will shift up since there is the slightest bit of flex in the neck of the bottle which is now directly affecting the barrel - they're both connected to one another.
I went ahead and zeroed my rifle by placing the bag on the end of the stock, not the bottle. I accidentally then rested the bottle of the gun on the bag and my POI shifted up as a result. Just something to be aware of.
If you like to rest your gun on the bottle for bench shooting, understand that your POI will shift up since there is the slightest bit of flex in the neck of the bottle which is now directly affecting the barrel - they're both connected to one another.
I went ahead and zeroed my rifle by placing the bag on the end of the stock, not the bottle. I accidentally then rested the bottle of the gun on the bag and my POI shifted up as a result. Just something to be aware of.
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I haven’t noticed that issue with my particular Crown, but I do see where that may be the case with Crowns and other carbon fiber bottle airguns. My bottle is snugged up pretty dang tight (not so tight preventing removal though). From the bench I tend to use my Accu-Tac bipod which is stock mounted (most of the time), and sand bags (partially). In the field its trigger sticks or some makeshift rest like a tree or post or whatever is available.
Thank you for your informational comment!
I appreciate it!
JoeKool
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Keeping with the theme of being thorough, here is some information about the Crown .25’s tune, accessories, and mods...
* Hawke Frontier FFP 4 -20 x 50 Mil Pro
* Huma-air High Pressure Regulator @ 170 bar
* Power Mod. / Hammer weight
* .25/.30 transfer port
* MAX hammer spring
* 600mm .25 Slug “A” liner
* 580cc FX Carbon Fiber bottle
* Above groups shot at these velocities w/ JSB King Heavy 33.95 MK1’s
hello dear.
Do you think you could give me any advice to maximize my Fx Crown Continuum .25?
I want to install a Huma regulator @ 170 Bars and TP with 2 holes.
I do not know if I have to hammer the hammer or some valve seat.
a chrono FX is on the way to know how much I'm pulling.
Thank you
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The best barrel support is one that allows the shroud to float inside it. That way it limits the deflection of the barrel when bumped so it won't take a set but doesn't push the barrel around. Think of it more as barrel bump protection than barrel support.
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I just put a barrel band on my Crown ; the band has a close fit around the barrel , almost no play , did you notice the same on yours ? Don't know if there is some effect on accuracy.
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I guess it depends on what you are trying to achieve. If the barrel floats in the ring, then it is receiving no support, although it might offer the feature you describe. Like any modification, each rifle is its own story, and you just have to experiment. Some rifles do well with very rigid support, such as the Taipan Veteran. My Revere came with a barrel band, and the barrel shroud floated within it as you describe. But it allowed a rattle with movement, so I took it off. Before removing it, I tried shimming inside the band to remove the movement and rattle, and to offer rigid support to the barrel. It shot okay, but I also noticed a small amount of shift in POI. It was not enough to matter for most squirrel head size targets, but it bothered me, so I removed the band. The rifle shoots great, and I've not noticed any POI changes without the band. Any bump the barrel receives in normal use does not affect its attachment, and it returns to the proper position, as demonstrated by its stable POI. Compared to many air rifles, the Revere barrel attaches to the action in a relatively rigid manner, and mine does very well with the barrel fully floating. Over many years of action and barrel bedding with CF rifles, I had consistently better results with the barrel fully floating. Usually, a pressure point would result in some shifting of POI, just as I noticed with the Revere band when it supported the barrel with contact. Some PCP rifles demonstrate a shifting POI when unsupported, as the Crown. And some use relatively weak methods of attachment at the breech. In those cases, I think that adding some support is worth trying, and it might improve the rifle's stability. Otherwise, I'm a believer in allowing a free floating barrel. With all this said, I try to remember, compared to firearms, most air rifles use relatively weak methods of attaching the barrel, and reasonable caution is required in their handling. A notable exception is the Taipan Veteran, as its barrels screws into the action, and is further supported by a system of 12 large machine screws that hold the scope tower in place. It could sustain quite a hit and should remain in place. It's also heavy and bulky, no free lunch I guess.
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Maybe. Depends on whether the barrel needs assistance from moving at the receiver or benefits from a change in harmonics. Ragged holes at 50 yards in real-world outdoor conditions is damn good. Could it be better? Maybe.
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This past summer their was a brief discussion regarding POI shift on Crowns. The discussion had some posts regarding what effect an egg shell foam case could have on POI shift. That was my interest. I have a Continuum with 380 and 700mm barrel. The 380mm barrel on the rifle fits the factory “cut out” style case without pressing on the barrel. I did some shooting, packed it in the factory case and then three days later fired it with no POI change. I was pleased. But the 700mm barrel installed on the gun of course will not fit in the case so when I take it to the range I set the buttstock on the passenger side floor mat and rest some point on the stock against the seat cushion so the barrel is untouched. I’ve only had it to the range once with the 700mm barrel. Probably would end up getting pulled over after a stop at a Mickey D’s drive thru. I plan to make a board like open case that the rifle can lay on with maybe some soft foam near muzzle to minimize disturbing the barrel. Summer 2023 project.
One thing I question is, if you look at the Daystate (1st photo) and Crown (2nd photo) notice that the full diameter Daystate shroud meets the receiver block. The Crown shroud has a cone shaped piece that necks down to the diameter of the piece that slides into the receiver. It would seem the Daystate, et al, would be a preferred way to mount barrels as the juncture just encourages better support. It does of course require all machined parts to be perfectly geometrically perfect so that the mating of barrel shroud and receiver is straight and true and all those good geometry and engineering words. Not owning a Daystate, I don’t know if there’s a slight gap or mechanical connection at the receiver. The only thing I can think is FX has researched it and feels their method is adequate or preferred or superior to other manufacturers. I’m pretty sure it would take a lot to bend a barrel on the Crown at the receiver. But if the gun fell over and the barrel struck something near the muzzle, I would say all bets are off. With the exception of some bullpups and springers the barrels are pretty durable in that regard. Personally I protect my airgun barrels (actually whole rifle) like a new born baby, but it would be nice to know how sturdy and resistant Crown barrels are in regard to POI shift from external contact.
One thing I question is, if you look at the Daystate (1st photo) and Crown (2nd photo) notice that the full diameter Daystate shroud meets the receiver block. The Crown shroud has a cone shaped piece that necks down to the diameter of the piece that slides into the receiver. It would seem the Daystate, et al, would be a preferred way to mount barrels as the juncture just encourages better support. It does of course require all machined parts to be perfectly geometrically perfect so that the mating of barrel shroud and receiver is straight and true and all those good geometry and engineering words. Not owning a Daystate, I don’t know if there’s a slight gap or mechanical connection at the receiver. The only thing I can think is FX has researched it and feels their method is adequate or preferred or superior to other manufacturers. I’m pretty sure it would take a lot to bend a barrel on the Crown at the receiver. But if the gun fell over and the barrel struck something near the muzzle, I would say all bets are off. With the exception of some bullpups and springers the barrels are pretty durable in that regard. Personally I protect my airgun barrels (actually whole rifle) like a new born baby, but it would be nice to know how sturdy and resistant Crown barrels are in regard to POI shift from external contact.
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I have both a Red Wolf and Revere, and both use the same shroud design as pictured. The shroud is held by a couple of grub screws at the base. It doesn't offer any significant support for the barrel (not its purpose), but it doesn't interfere with it. The sliding shroud design on the Crown is a potential issue, since it not only lacks support for the barrel, but gains a leverage effect as it is moved farther out on the barrel. The effect of a bump in its extended position is amplified considerably, although I don't have the math skill to calculate such stuff. And, different positions will create different changes in barrel harmonics, it becomes a tuning device. When combined with the sleeve/liner design, rather than a solid barrel, the variables add up. Typical of my experience with FX, it is a design that can be a delight to tuners and tinkerers, but a challenge for the hunter who needs to be confident of a stable POI. Full disclosure, my experience was with the earlier Crown generation, and I know that improvements have been made.
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This is a little modification I made today on my Crown . I've never put a lot of trust in the way the FX Crown barrel assembly was kept in place in the action . The 2 grub screws have a rather flat bottom , and the contact surface with the round barrel is , in my opinion , not ideal . So I removed the screws , carefully pointed the center in the barrel and , using a 60° ,2,5mm drill , drilled 2 "dents" in the barrel , about 1mm deep . On my lathe I turned the grub screws to a 60° pointed bottom. In this way , it's impossible for the barrel to rotate or going back and forth. See drawing.
Frankly , I don't know if this modification can improve the gun in a way or another . I'm sure that the FX engineers know what they do , but it was something I wanted to change for a long time .
It's VERY windy today so I didn't shot the gun . I'm just curious to see if this little mod + a barrel band could decrease the POI problems I have with this gun.
Frankly , I don't know if this modification can improve the gun in a way or another . I'm sure that the FX engineers know what they do , but it was something I wanted to change for a long time .
It's VERY windy today so I didn't shot the gun . I'm just curious to see if this little mod + a barrel band could decrease the POI problems I have with this gun.
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Well, in theory, you'll have positive locating and I'm guess, less need for torquing it tightly, distorting the barrel.
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