Fx liner quick fit (mk2 update)

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bucketboy

bucketboy

Member
Apr 5, 2019
1,190
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Lincolnshire, United Kingdom
I have never been happy with the way the liner is held in position on my impact so needed to come up with a better solution. My plan was to use one of these ER16 collet chucks and fit it onto the end of the barrel sleeve.


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However, due to accuracy issues I have with the impact I wanted to test my liner for accuracy on another gun to ascertain if it’s the barrel, the gun or my ability to shoot the impact properly that the problem so I needed to find a way of fitting the fx liner to one of my theoben rapids which I know is super consistent , without the need to do any alterations to the liner



what I did was machine up a short length of bar to fit in the rapid block, bored it out to except the fx liner then fitted the ER16 collet to the barrel, with a delrin collet and the lock nut, the liner is held firmly and 100% concentric to the block. 


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To remove the liner there is no need to remove the nut just slacken it and pull out the liner, to index, slightly slacken the nut, this will allow it to rotate. when fully tightened, the lock nut causes the liner to move back a few thou and puts the o ring in the short barrel assembly under compression making a perfect seal.




I will fit a full length carbon shroud to support the liner, making it stiff and extremely light.



Bb





 
A quick update, I haven’t had time to make a shroud to stiffen the liner, so I made a sleeve extension instead 

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It’s blowing an absolute gail over here at the moment but I decided to go to the range and try it out.

I optimistically set the target up at 25yards, primarily to index the barrel. I marked the barrel and took 6 shots at the 12 o’clock position, indexed the barrel to 3 o’clock, then 6 and 9 o’clock. With a bit of fine tuning I settled on the 2 o’clock position being the highest and theoretical the best.

This is an index map, the dots are the centre of the groups, the coin is for reference of size, I was surprised how big the spread was at only 25 yards.



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After locking the collet up tightly to eliminate the possibility of movement, I zeroed the gun at 30 yards. These are 5 shot groups with different pellets without altering aim point. Considering the very strong wind, I was very happy with the results 



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At 55yards the groups opened out slightly (not surprising given the conditions) but regardless of pellet brand or weight they impacted in almost the sam spot. some of you may not be that impressed by the groups being only 30yards, but I am not shooting at 35-40fpe, this is 12fpe and the pellet speed it 570fps..



This is only a prototype, I will be making a more permanent solution that will have a full length shroud to both stiffen and quieten, hopefully this will improve things still further. I am seriously thinking about fitting this collect to all my guns as barrel replacement or indexing could not be simpler.



I had a very rewarding few hours testing today 👍



Bb
 
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Did you ever contemplate the accuracy problems with projectile seating depth in the Impact with the E16 system? Second question would be does that system provide adjustability for the placement if the breech?
Click to expand...

Sorry I missed this, 

I never got around to fitting it to the impact but the collet makes no difference to the breech, all it does is holds the liner securely without putting the liner under compression. I can fit any length liner without the need to change the sleeve and indexing the barrel for optimal placement is very easy.



The prototype fitted to my rapid certainty shows potential. With a slight modification the collet fitted to the block would make complete barrel replacements a 30 second job. After chatting to an engineering fried of mine who is also a keen air gunner, he has already made up a few of these on his CNC machine, that work the same but look a whole lot neater. 


Bb
 
Upvote 0
Did you ever contemplate the accuracy problems with projectile seating depth in the Impact with the E16 system? Second question would be does that system provide adjustability for the placement if the breech?
Click to expand...

Sorry I missed this, 

I never got around to fitting it to the impact but the collet makes no difference to the breech, all it does is holds the liner securely without putting the liner under compression. I can fit any length liner without the need to change the sleeve and indexing the barrel for optimal placement is very easy.



The prototype fitted to my rapid certainty shows potential. With a slight modification the collet fitted to the block would make complete barrel replacements a 30 second job. After chatting to an engineering fried of mine who is also a keen air gunner, he has already made up a few of these on his CNC machine, that work the same but look a whole lot neater. 


Bb
Click to expand...

Brilliant and inspirational idea. I'm considering something very similar to this now for my Taipan (for FX liners). 
 
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I have been testing this for the past week or so, shot about 1000 pellet through it and have fitted a shroud and moderator. The barrel has been in and out 1/2 a dozen times, the liner has been in and out at least 20 times, the shroud and mod have also been on an off many times.

The results are very promising, the maximum zero shift I have had either vertically or horizontally @25yards is just 4 clicks on the scope.

I have some er16 collets on order, one of these will definitely be fitted to my impact. I haven’t decided yet on what length liner I will fit on the rapid, I may cut it down to 400mm. Still testing but looking good.



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Bb
 
Upvote 0
After successfully testing the collet idea on one of my rapids, it was time to fit the mk2 version to my impact that suffers from zero shift. I am convinced it’s the liner crush nut that’s the problem.



All I did was cut 2” of the barrel sleeve and fitted a er16 collet chuck to the end. I then made a delrin baffle the supports the shroud and also increases the Dia of the liner to 10mm to suit the collet.

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the collet grips the liner firmly without putting it under compression or causing damage, holds it 100% concentric to the sleeve, and the baffles 100% concentric to the shroud. Index could not be easier, slacken the nut slightly, turn the liner, pinch up nut, job done.



It definitely works on my other gun, testing the impact tomorrow, see how it performs.



Bb
 
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