Tuning My FX Crown has its barrel tensioned !!

[aldea6]

I finally put a carbon barrel tensioner on my FX Crown . Using some aluminium tube 14X16mm as a sleeve to adapt the 16X20mm carbon tube over the 14mm OD barrel. It sure increases stiffness and accuracy , that's the good point. But now the gun is not backyard friendly anymore ,...it's pretty loud even in .22 cal.
So would it be possible to put the shroud back around the carbon tube , in a way or another ? I'm back to my drawing board to find a solution , some machining will be needed , but I wonder if somebody else has already undertaken this project ? Unless noise is not a problem for you .

 

[Scotty1]

I’d love to see pics of what you’ve done so far, it may inspire some new ideas?

 

[woogie_man]

Assuming you don't have the ultra light weight barrel on the Crown?

 

[aldea6]

No , it's the old system : a liner in a tube in a shroud . No stiffness in this system .

 

[Long_Gun_Dallas]

Sounds like an older (non-superlight) barrel. The threaded bit for the muzzle would need to have moderator threads as well on the front.

 

[aldea6]

This is the way E. Rowe installed the barrel tensioner....fast and simple

Now this is the barrel system

My idea is the same as E. Rowe ,but using the "air stripper" (3) instead of the moderator to tension the barrel , slide the shroud (1) over the tensioned barrel and scew the moderator on the end cap (4) .

What do you think ? Am I mistaking somewhere ?

Thanks for your opinions / modifications

 

[qball]

I’ve done that with a STX barrel, it is louder but you just need a bigger/longer moderator. It is indeed very stiff, I grabbed it by the barrel and leaned on the barrel too with no issues. I switched back to superlite because it is much lighter, quieter and seems slightly more accurate with the barrel free floating.

 

[aldea6]

I forget to put the aluminium 16X14mm on the barrel to compensate the diameter difference : 14mmfor the Crown , 16mm for the Impact and the Carbon tube.
I made a short test and it works . Of course the volume inside the shroud is decreased , so less effective..;

 

[aldea6]

I’ve done that with a STX barrel, it is louder but you just need a bigger/longer moderator. It is indeed very stiff, I grabbed it by the barrel and leaned on the barrel too with no issues. I switched back to superlite because it is much lighter, quieter and seems slightly more accurate with the barrel free floating.

Yes , you"re right . A stiffer barrel could support a bigger moderator .

 

[aldea6]

And , oh yes .....I keep the semi-conical plastic part which goes into the action ; the carbon tube comes against it.

 

[qball]

Yes , you"re right . A stiffer barrel could support a bigger moderator .

Yes, I tried different moderators and hang the FX chrono on it with zero POI shift.

 

[aldea6]

Job is completed ! I keep the shroud attaching system in place , put an aluminium spacer between it and the carbon tube , screw a bigger moderator to put the barrel in tension and shot some good groups , about 3/4" at 55 yards , JSB 18gr at 870Ft/s. the gun is very quiet without the shroud , but will be perhaps much louder with heavier calibre . Anyway the shroud can be put back in place with the carbon fiber , using the "air diffuser" to tension the barrel , and a moderator can be screwed at the end of the shroud , in the usual way .

Now I'm curious to see if the gun will keep its POI ? Let's hope

 

[jking]

I did a BC tensioner with the factory Crown shroud mod. I machined a Delrin adapter to fit the 14X20 CF that the factory shroud can screw back onto, replacing the cone shaped shroud piece. I guess the factory cone piece could be used if you wanted to sacrifice it and the associated lock ring. It might also be tricky boring it out and short as it is. A small hole was also drilled into the 14X20 CF for a set screw to recess in. Without it the shroud wants to go airborne. My adapter was looking great up until the lathe decided to take a bite into the thin end of the Delrin which mangled it pretty bad. The threads didn't turn out like I wanted using the lathe to cut them so I'm going to make another with a 27X1.5 die. The threads are good enough though that it does screw on and hold the shroud in place with no forward movement. Using the factory air stripper and the factory shroud is definitely quieter than just the BC tensioner and the FX moderator. I tried a Sumo as well and it's not any quieter than the FX. Overall, with the tensioner doing its job and the FX shroud doing its job I'm really pleased.

 

[aldea6]

Very nice job . I kept the conical shroud piece and put an aluminium spacer , because the BC tensioner was made for the Impact , and was too short for Crown. As you stated in another post , I'll use a steel nut to tension the barrel and screw the air stripper behind . My Crown is in .22 now and quiet enough without the shroud . I would like to swap the barrel for a .30 , and I think that the shroud will be needed , even with a Donny fl Sumo.

By the way , what's the calibre of your gun ? STX slug barrel ?

 

[aldea6]

OK , so this morning I put the carbon tensioner with a steel nut , then the air stripper , put the shroud back and the moderator at the muzzle of the shroud , took a few shots.....absolutely no difference. So now I remove the shroud and let the carbon tube "naked" with the moderator.

Too much wind these days to try a decent group . Wait and see.

 

[jking]

Very nice job . I kept the conical shroud piece and put an aluminium spacer , because the BC tensioner was made for the Impact , and was too short for Crown. As you stated in another post , I'll use a steel nut to tension the barrel and screw the air stripper behind . My Crown is in .22 now and quiet enough without the shroud . I would like to swap the barrel for a .30 , and I think that the shroud will be needed , even with a Donny fl Sumo.

By the way , what's the calibre of your gun ? STX slug barrel ?

I have it set up as 30cal right now with a superior liner.

 

[Carlosdec]

Better accuracy ?