FX Crown barrel band. Unnecessary, yet necessary... (New)

Looks good, is that finish on the stalk factory or did you coat it?

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Thanks, yes sir I refinished the walnut stock.

One problem with plastic bands is they have a significantly different thermal expansion than metals which can yield POI shifts as the temperature changes. Also, the bottle can move under pressure changes.

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It would be great if you could trial this to see what real world effect temperature change has on your POI with a plastic barrel band.

Whats the temp where you are? Could you leave your gun right next to a radiator perhaps for an hour and shoot a group?

Id love to see the results....

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You guys raise a good point. I will try this test @ 50 yards. First, I’ll take five shots at normal temperature at a target. Then I’ll carefully heat up my 580cc carbon fiber bottle and barrel support band and take another five at the same bullseye. I’m no scientist, but I doubt the POI shift will be great. But we’ll see... I will post the results.

I like it but why so far back the closer to the end the more support .

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Thanks, well I rest the bottle on my sand bag and/or my shooting sticks quite a lot from the bench or when hunting so, did not want to obstruct or disrupt my shooting tendencies. It offers the same support anywhere you place it, respectively. It’s back far enough to be effective, out of the way, and not get damaged. Also, looks better where it is IMO..



I may add that the barrel support is tight around the carbon air bottle, but has enough tolerance to slide along the barrel shroud. Providing ample support to hold the barrel in virtually one position. Preventing barrel flex, making the Crown’s STX barrel about as solid as the previous solid steel Smooth Twist barrels were.

I am very interested in the results of your testing. Please get back to us on your results.

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I plan to do this test later today and post the results, using a heat gun, laser temperature gun, and shooting 10 shot groups @ 50 yards.

So are we trying to simulate some sort of extreme temperature change? seems a highly unlikely scenario. Anyways did you make that band yourself?

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So are we trying to simulate some sort of extreme temperature change?

Yes



seems a highly unlikely scenario.

I know... Doing this for you guys not myself, I know the gun is accurate with the barrel support. A PCP’s air reservoir can get pretty toasty (hot) out in the dead heat in the summertime. Just a makeshift Airgun experiment. A couple of guys above in this thread were asking. Proofs in the pudding, hey it’s an excuse for more airgun target shooting!



Anyways did you make that band yourself?

No I did not make it.

ebay link:

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F223930959139

Conducted my ambient temperature vs hot temperature FX Crown accuracy test this evening. Trying to simulate how a mild temperature day vs a very hot day may effect the accuracy of my barrel support banded Crown .25.


Wanting to illustrate how much if any, POI shift would take place from the heat expansion of the 580cc carbon fiber bottle. While using a plastic 3D printed barrel support band.

”Remember this is only a test”....

Meaning, I am not in a lab and I know that they’ll be many variables I may not be factoring into this. It was fun anyway, and I did learn something. So here goes! (warning picture heavy)



First, set up the 50 yard target.









Wind.







Second, get the ambient temperature of the Crown’s air bottle. (73.7 Degrees F)







Third, shoot a 10 shot group with the barrel band installed at ambient temperature (73.7 Degrees F). Using JSB King Heavy 33.95 grain @ 50 yards.









Next, shoot only a 5 shot group at the far left target again at ambient temperature.






Now, I carefully and slowly heated up the Crown’s 580cc carbon fiber air bottle. Using a heat gun on the lowest setting. Temperature of CF bottle reached (105.1 Degrees F). Out in the summer sun hot!









Okay then, with the bottle at (105.1 Degrees F) I shot 5 more shots at the same far left target. Completing a 10 shot group with half the group (5 shots) at 73 Degrees and half the group (5 shots) at 105 Degrees F. Barrel support installed mind you... This group simulates the metal expansion which theoretically should cause POI shift.






The group is larger, but still is just a single jagged hole...



Lastly, is this barrel support band going to help my FX Crown .25 shoot more accurately then without the barrel support installed at all?



Top target still @ 50 yards, barrel support removed, carbon fiber bottle cooled back down to ambient temperature. 10 shot group!









WOW!  



(Top target) This 10 shot group with no barrel support was smaller than them all! It may be the tightest 10 shot 50 yard group I have ever shot with this airgun!!


Test Completed.



***Target close ups***



73 Degree F (with barrel support) 10 shots, 50 yards

5 shots @ 73 Degrees F CF bottle (with barrel support band)

plus

5 shots @ 105 Degrees F CF bottle with barrel support band)

Total = 10 shots 

50 yards

10 shot 50 yard group ambient temperature (no barrel support band)

Learnings and Conclusion:



Bye-bye barrel support... I guess you shouldn’t mess with a good recipe! Shes (the Crown) is going “Commando” from now on! No barrel band for this baby, hey it was worth a “shot”, but my FX Crown .25 has been shooting lights out since I got her back in 2017. I can’t argue with these results. As far as the temperature and/or metal expansion using the barrel support band, yes it does effect POI but not (at least for this test) a great deal. It resulted in a larger, but still a single hole group. Oh well, I may play with the barrel band some more in the future, but this Crown is going back in the case without it..



This was interesting .

Thank you for taking the time to try all of this out for all of us here . Nice job ! 

This post will definitely be referenced in the future .

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Sure thing, and you’re welcome!

Very thorough, and very interesting!

Now if you wouldnt mind leaving your crown in the freezer for 2 days.....

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Lolololol... freezer!

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