Anatomy of Barrel Bushings
Hello,
We all know how important proper barrel bushings are. Unfortunately AirForce cut some corners with them and they are made from plastic. The problem with plastic bushings and current way to fix them is the co-centric alignment – especially if you accidentally knop the barrel.
Just yesterday I experienced this. I shot 30 shots from 25 meters with decent accuracy and then got little sloppy. I was loading my gun and accidentally hit the barrel against chair. Not hard. Just hold the gun in my hands and turned around little sloppy. POI shifted 10mm immediatelly.
Why did that happen? Well, the current plastic bushings are fixed with couple of allen screws. Longer from bottom all the way to barrel and another one from side. That hit to barrel caused about 0.04mm disalignment in bushings. Thats 10mm at 25meters.
I thought that now is the time for new and better bushings. Made quickly 3D-sketch from what I have seen with other people. This is not my design – just a copy of decent bushing thats been made many times. I wanted to share the pictures with you so that newbies can grasp the idea quickly.
Material is Aluminium. First bushing has venting-holes.
Idea is to lock and fix the bushing against barrel tightly with 3 allen screws from 120 angles. Top screw goes to hole in barrel. Bushing are with very thight fit to barrel. They will be turned little over-sized (26mm).
Assembled and screws tightened to barrel. THEN the barrel will be put in lathe and the bushings OD and O-ring slots are turned. This makes them perfectly cocentric with barrel. The OD has small gap between frame and the aligment is done with O-rings using 20-25% compression. This should avoid the misalignment even with slight hits to barrel which are unavoidable for me at least. Finally the assembly is insterted to frame and fixed with allen screws in frame. These screws will not go all the way to barrel as they used to do but just provide axial locking. There is no thread in bushing for screw – just a hole.
Hope this makes sense and please feel free to provide more tips and comments.
-mike
All Replies
I would just make new tight fitting bushings end pull the screws tight! Not stripping the threads ofcourse.
Regards,
Marc
What retailer and in what country did you buy your gun?
Wont the O-rings only be helpfull if they resist movement by offering friction with the frame.. and if thats the case, wont it make it impossible to push them into the frame when installing them? I guess some kind of evaporating lube would overcome that…
I dont see a problem with the barrel moving relative to the bushings, but the entire barrel/bushing combo moving relative to the frame.
Very good points. Thanks!
I don’t think that the movement will be an issue. The bushning are fixed pretty secure to barrel (3 screws and one of them in the recessed hole on barrel). The modified allen screw on frame (or both of them) will go to precise hole and lock axial movement. But then again – we will see after testing. I would just love to have a semi “floating barrel” and thats why I wish to try this design.
And I don’t plan to make these for sale just for myself so the fitting is not a problem. I calculated that O-rings will allow quite a big tolerance for frame inner diameter (1″ +- 0.1 mm easily). I want to turn the O-ring slots when bushnings are assembled to make sure that last 1/100th millimeter is cocentric.
btw, I received my standard Talon just few weeks ago and it still had delrin bushnings. But it also has older valve without O-rings on valvestem. Hmm.. Maybe it came from bottom of stock or are you sure AF has changed all models?
We wont know until its tried… But I think that not having the bottom set screw touching the barrel would allow too much movement.
If all the tolerances were super tight then it will work great I’d bet. But to send them out to people without fitting them to a gun I think there will be too much movement. The rear bushing supports the Power wheel and hammer spring pressing into it one way, and then the force of the pellet leaving the barrel exiting the other way, if there is any chance for movement then it will move. A set screw pressing from the frame into properly recessed points on the barrel at 4 points (2 bottom, 2 side) should prevent that and allow them to utilize looser tolerances.
My feelings are based on owning a .22 Condor that had Delrin bushings which I replaced with aluminum bushings I turned. I currently have a .22 SS with Delrin bushings which are soon to be replaced with Aluminum. Properly sized bushings I made for the Condor wouldnt fit the SS as they were too big, I dont know if thats a Model to Model issue, or just pot luck with all guns on what size the inside diameter of the frame is.
Also… Air Force seem to have realised the Delrin issue and newer guns have Aluminum bushings and all guns now have 4 points of contact with the barrel, not just two full size underneath that touch barrel along with two small set screws on side of frame pressing on the outside of the bushing as it was originally on the Condors, and just 2 points underneath on the SS and Talon.
BUT… dont let me stop you. like I said, we dont know unless we try in this game and guys have tried some crazy things and found they work. I’d LOVE to be proved wrong and would be among the first to buy these!
- You must be logged in to reply to this topic.
4 Comments
-
Pingback: Sexy gaming
-
Pingback: jav
-
Pingback: สล็อต เกาหลี
-
Pingback: Ulthera
I live in Finland and used local retailer. The gun was ordered from US and I have a feeling it was directly from AF but not sure. Is there any confirmation if and when the bushnings and valve has been changed for standard Talon?
The O-rings will just provide cocentric alignment for bushings+barrel against frame. The allen lockscrew on the frame will lock the axial movement of bushings+barrel group. I would like to try true free floating setup also but I think the barrel is not big enaugh (=strong) for that. So I think I try something in the middle. I will lock only the rear bushing to frame and try front bushing without any connection to frame other than O-rings (=semi floating or bedded setup).
This is propably enaugh since the temperature and expanding is not problem with airguns. What do you think about using compression tolerance for bushings + barrel group? Providing mild heat to bushings during assembly. I was thinking something around P7 or so. Removal could be propblematic but not impossible.