ST-X barrel sleeve swap problem

[Bob_O]

Hey guys.

Tried to swap sleeves tonight and ran into an issue where one caliber barrel adapter fits perfectly into both 500 and 600mm sleeves but the other caliber adapter will not.

You can see by this pic that the threaded portion of both adapters have exactly the same dimensions and threads. 

Please watch the short video if you have time. Any suggestions will be welcome.

Thank you.





https://youtu.be/wIo8Xl7z5po

 

[Glem.Chally]

Are the outside diameters exactly the same at the very tip between the .25 and .22 steel parts? On the right of the threading in your comparison pic.

Like have you checked with calipers.

 

[Bob_O]

I was just about to post. Thank you Glem, you nailed it!!

Scratching my head over this for two hours, cleaning threads over and over, test fitting, etc. 

So I grabbed the calipers and decided to measure the exact spot you mentioned, and sure enough the 22 caliber barrel adapter is 0.10mm larger diameter.

11.8mm for 25 caliber and

11.9mm for 22 caliber.

That explains why the 25 fit in both sleeves.

Hmm, what to do now. I wonder if a machine shop could turn it down 0.1mm?

 

[Glem.Chally]

They could easily, you could probably too like if you wrapped a strip of aluminum can around the threads the brass inlet threads onto. Chuck it up in a drill vvery gently and focus on the last 1/4 inch like you said it needed and use 800 or 1000 grit and go slow. You could do it.

 

[Bob_O]

Thank you so much Glem!

I already test fitted the 22 caliber liner retaining nut in the other end of the longer sleeve and it fit no problem.

Just couldn't for the life of me figure why I had the other fitment issue.

 

[Glem.Chally]

Thank you so much Glem!

I already test fitted the 22 caliber liner retaining nut in the other end of the longer sleeve and it fit no problem.

Just couldn't for the life of me figure why I had the other fitment issue.

No worries buddy.

 

[DrOcean]

People who know more than me have problems too. Good to know! Glad you seem to have it sorted.

 

[Bob_O]

I'm going to try the local machine shop in the morning. They actually milled a part on the Wildcat for me last Spring.

Should be easy for them.

 

[kzz1kaw]

Did you contact fx about this problem?

 

[mtnGhost]

If it were me, I would figure out which threads were problematic and buff them down like Glen mentioned. I've had to do that in the past with some irregular sized threaded bolts. 

It sounds like you got it covered with a machine shop though! 

 

[Bob_O]

I don't think the threads are the issue as they are in perfect condition. It's the unthreaded portion of the adapter being slightly larger that makes it so it won't seat.

The threads inside the sleeve are only cut so far. From there it's just the smooth inner wall. That's where the slightly larger diameter adapter can't fit.

I'm going to stop at the machine shop in a couple of hours. I'll update if they have time to do this for me.

 

[Bob_O]

Did you contact fx about this problem?

If I can't get this part to fit with just a little effort on my end, I will contact FX. Until then, it's not the end of the world.

 

[jwrabbit123]

Gee BOB sorry for your issues , I think you are saying the part is oversized a bit , is this defective? It should fit all FX parts ? I do own a medal lathe , wouId be glad to turn it down for you , but I am not understanding Why you should have to LOU



.1mm is like .004 very little material

 

[Spray1Mark]

WOW! going to do this exact same thing tomorrow myself so great timing, .22 600mm B liner into my .25 600mm sleeve as my .22 sleeve is only 500mm.

Will make sure to check, but turning down will be easy anyways.

Thanks for the heads up!

 

[STO]

This is good to know, thank you Bob. I too had future plans to convert a .25 kit to run a .22 liner. I do wish FX would sell just the sleeves, it seems somewhat exploitative that they sell all these different barrel liners, but in order to do a conversion you have to buy a lot of unnecessary parts. 

 

[GK1973]

Thread lenght problem.

Cut down rhread lenght for a bit and will be ok

Check out first lenght thread in tube

 

[Bob_O]

Thread lenght problem.

Cut down rhread lenght for a bit and will be ok

Check out first lenght thread in tube

It's not the thread length......as one goes all the way into both sleeves but the other doesn't. Measured a difference of 0.1mm larger for the one that doesn't fit.

Just left the machine shop, they might be able to do it today....if not, tomorrow morning it will be ready.

Jw,

IIRC, the guy whose going to do the work said it was .004 difference. He measured the adapter that fit and is going to mill the other one to the same diameter.

The weather is crap anyway so I wouldn't be shooting even if I had it together.

 

[jwrabbit123]

ok BOB let me know ,

 

[L.Leon]

Bob, the adapter on top has 14 threads, the one on the bottom has 13... does that matter?

 

[Bob_O]

Yeah. It won't even try to thread into the wrong end.