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All Springer/NP/PCP Air Gun Discussion General > "Bob and Lloyds Workshop"

Carbon fiber tube questions

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rkr:
Mike, my experience with long airgun barrels is that you need a tight barrel band for consistent accuracy. The best group with that setup so far is 12.5mm 5 shots at 100M and I did 3 groups under 15mm in that range session.

mackeral5:

--- Quote from: rkr on March 06, 2023, 03:58:00 AM ---Mike, my experience with long airgun barrels is that you need a tight barrel band for consistent accuracy. The best group with that setup so far is 12.5mm 5 shots at 100M and I did 3 groups under 15mm in that range session.

--- End quote ---

I do appreciate your real world experience.  Your. 257  one I often use as a point of reference, a point of measure.

 On a short tubed gun such as the brod pictured, do you think a barrel band at the tank block would be worth the effort?

My .25 Gauntlet is setup that way and can shoot accurately.  However one must NOT touch the tank, or POI will move.  Applying any vertical or lateral pressure to the tank normally results in a POI shift.

The Brod tank/block interface is much more robust than the Gauntlet, perhaps it would not be as sensitive.

I may try to fab up a temp/reversible solution and test. 

Spacebus:

--- Quote from: mackeral5 on March 06, 2023, 07:19:27 AM ---
--- Quote from: rkr on March 06, 2023, 03:58:00 AM ---Mike, my experience with long airgun barrels is that you need a tight barrel band for consistent accuracy. The best group with that setup so far is 12.5mm 5 shots at 100M and I did 3 groups under 15mm in that range session.

--- End quote ---

I do appreciate your real world experience.  Your. 257  one I often use as a point of reference, a point of measure.

 On a short tubed gun such as the brod pictured, do you think a barrel band at the tank block would be worth the effort?

My .25 Gauntlet is setup that way and can shoot accurately.  However one must NOT touch the tank, or POI will move.  Applying any vertical or lateral pressure to the tank normally results in a POI shift.

The Brod tank/block interface is much more robust than the Gauntlet, perhaps it would not be as sensitive.

I may try to fab up a temp/reversible solution and test.

--- End quote ---

I like Bob's idea of just using some kind of shim and worm gear bands.


I did go ahead and order the BR kit and CF tubing. In a week or two I'll be experimenting. I may even wait until after hare season is over.

rkr:

--- Quote from: mackeral5 on March 06, 2023, 07:19:27 AM ---
--- Quote from: rkr on March 06, 2023, 03:58:00 AM ---Mike, my experience with long airgun barrels is that you need a tight barrel band for consistent accuracy. The best group with that setup so far is 12.5mm 5 shots at 100M and I did 3 groups under 15mm in that range session.

--- End quote ---

I do appreciate your real world experience.  Your. 257  one I often use as a point of reference, a point of measure.

 On a short tubed gun such as the brod pictured, do you think a barrel band at the tank block would be worth the effort?

My .25 Gauntlet is setup that way and can shoot accurately.  However one must NOT touch the tank, or POI will move.  Applying any vertical or lateral pressure to the tank normally results in a POI shift.

The Brod tank/block interface is much more robust than the Gauntlet, perhaps it would not be as sensitive.

I may try to fab up a temp/reversible solution and test. 

--- End quote ---

I would give it a go, as said copy Bob's design and if it improves your groups you can then try a more permanent solution. I have my barrel band attached to both air tube and the stock making it extra stiff, perhaps you could try making some sort of extension for the stock that extends under the bottle and ties to the barrel band? It would be a good idea for rested shooting as well.

Spacebus:
A bit more detail as to what I'm planning to do.

To keep the M-Lok rail from rotating around the air cylinder I'm going to drill a hole where the two pieces come together (two joined semicircles) and slide a 2mm CF rod into the hole and tension it (M-Lok rail) against the receiver and grip with CF tube.  I've decided to get some 16x12 and 18x16 mm tubing and some different sized O-rings in an attempt to keep everything centered/concentric once it has been tightened down. There are some nice stepped sections on the muzzle end of my barrel that should be perfect for holding some o rings. Hopefully it will look nice and be functional. Clearances will be tight around the drop block and I may have to file some flat spots on the CF tube or the drop block. To evenly apply pressure to the oversized CF tubes I got some 12x18 mm stainless washers. The whole setup should look just like an 18 MM OD CF shroud with an LDC hanging off the end, which might be a future project.

Would it be better to glue the CF tubes together or let them slide? Should I sandwich o-rings (or some other gasket material) between the CF tubes and the M-Lok rail/barrel band or LDC?

The picture shows a red circle where I want to drill the hole through the M-Lok rail (tri-rail in the pic) and the grip. Maybe 2mm is too small? I also considered drilling holes into the grip in the same axis as the barrel and then gluing in CF pins with corresponding holes on the M-Lok rail. Either option should keep the rail and the barrel from moving.

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