Discussion in 'General Airgun Chat' started by Ratinator, Nov 19, 2018.
My 2 cents: Followthe ordinary B plan and use a sanding drum on the Dremel.
Not sure if the picture shows it properly but my guide highlighted the fact that the barrel hole is offset to the larger hole on the back of it .
not an easy thing to get right without a horizontal boring machine ! how about making a stepped mandrel that locates in the breech, long enough to be able to use it as a guide then try and sort out a cutter that will rotate about it ,the hole should then be concentric and in alignment with the barrel , just an idea . I was considering fitting a shroud a while back so gave it a little thought.
Maybe something like this :
Or make a pilot end cutter
Now that's a thought
The pilot is a good idea, though, my steyr barrel is nowhere near the centre of the chassis , as the fit in the breech is what we used to call a "piss fit" and once the grub screws are tightened its cocked over . Maybe its just mine .
For God's sake theres alot of pratting about here, just open it out with a Dremil, its only at the end of the chassis. I've done 2 Challenge chassis's now by hand with no problems at all.
If anything it doesn't need to be perfectly round either, its the right hand side that needs more removing due to it indexing when the grub screws are tightened. Thats why it's offset from the factory.
So why don’t they offset it to the right ?
Mine is and so does the one in the photo unless its a trick of the light
Trick of the light Neil , it’s out of line with the outer hole from the bottom.
I had an o ring on the end off the barrel to start with that fitted loosely in the large hole , it gave it a tiny gap all around the barrel.
Did mine with a dremel.
The fit in the breech is baggy .
I thought this was by design .
The bottom of the breech hole looks like the arc of a circle of smaller diameter than the barrel and acts as a vee would when the grub screws push down from the top.....hopefully centering the barrel
Wow , I hadn't considered that, why wouldn't they just put a decent bore in, maybe so the barrels don't have to be too tight a tolerance, and why some touch the chassis at the front and some do not ?
All you need is a rusty old file Simon and half a bottle of vodka, you can't make a steyr any worse
I machined the barrel locally to the contact points.... now I can put it back to original with a new barrel rather than a new chassis
You know you want one really Marc .
Are you coming out to play Sunday at greyhound ?
Questions x 2
How far from the end of the chassis ( muzzle end ) is the furthest support ( the support nearest the breech ) on a challenge ?
or how long does a tool need to be to feed through from the muzzle end to clear all the holes ?
what are we thinking inside diameter wise Gang ? The barrels are typically 16mm , so what do you reckon ?.... 18 mm hole ? ......19 mm?
edit i suppose the 20. 5 of the original large id would work
I'd be inclined to go with the dremel approach and take it carefully checking with the ring for concentricity.
Are you planning on completely free-floating the barrel or sticking a nice fat o ring in there to give some cushioning?
My lg100 only has 1 barrel grub screw so was thinking of leaving the fat o ring in as a front support .
I’ve done it before and does not seem to create any poi issues .
I have just ordered a cutter from evil bay for £1.98 delivered , its 20mm as i intend to use a small diameter barrel maybe 12mm, and shroud it , if i ever get round to it !