Loose barrel

[rkr]

My Evanix Sniper has a loose barrel, by loose I mean that it moves up&down + sideways when I remove the set screws that hold it in the breech. I don't quite like that so I'm looking for suggestions of how to fix it. I was thinking of some epoxy or chemical metal for the barrel but as I want the barrel to remain removable I need a release agent for the breech part. Any ideas what would work?

[Madd Hatter]

Meguiars mold wax. Put that on there with a room temp cure epoxy or whatever and it will not stick

[subscriber]

Wrap the barrel in Scotch tape until the diameter is a light press fit in the receiver, then tighten the screws moderately.  This reversible.  Epoxy may or may not be reversible...

If tape bugs you; wrap the barrel in at least one layer of thin shim stock...

[rkr]

Wrap the barrel in Scotch tape until the diameter is a light press fit in the receiver, then tighten the screws moderately.  This reversible.  Epoxy may or may not be reversible...

If tape bugs you; wrap the barrel in at least one layer of thin shim stock...

There are two steps in the barrel diameter that goes inside the breech so wrapping material around it properly is not easy. In addition this is a 270 fpe gun so there's some whip on the barrel when fired. That wax sound like something I could try.

[Madd Hatter]

Just remember that aluminum expands and contracts so the temperature the epoxy resin cures at will be zero clearence so the barrel could be hard to remove unless the receiver is at the same temperature or warmer.

[mobilehomer]

Make sure you tighten the screws in the same order to the same torque every time and don't worry about it. There might not be enough clearance between the two to fit anything. Just .002 or .003 difference will allow the muzzle to move quite a bit.

[subscriber]

There are two steps in the barrel diameter that goes inside the breech so wrapping material around it properly is not easy.

Wrap each diameter separately.   The total contact area will be quite large.  Even tape will be quite stiff, f it is wrapped without trapping loose loops. 

Use JB weld with steel powder in it, if tape sounds too flimsy.  Put the release agent on the barrel...

[WhatUPSbox?]

Aluminum tape can be burnished down to pretty thin layers. Maybe put some lube on the outside to make removal easier.

[Madd Hatter]

There are two steps in the barrel diameter that goes inside the breech so wrapping material around it properly is not easy.

Wrap each diameter separately.   The total contact area will be quite large.  Even tape will be quite stiff, f it is wrapped without trapping loose loops. 

Use JB weld with steel powder in it, if tape sounds too flimsy.  Put the release agent on the barrel...

Aluminum powder would be better as there wouldn't be any risk of galvanic action between dissimilar metals. Forgot to also say that copper will eat aluminum.

[subscriber]

Aluminum powder would be better as there wouldn't be any risk of galvanic action between dissimilar metals.

I am sure that epoxy with aluminum filler will work just as well.  That said, the steel or aluminum in the epoxy should be shielded from atmospheric moisture by the epoxy itself.  Each granule of metal filler is surrounded by non-conductive epoxy, unless the filler content is unusually high, or the glue was not well mixed.

If you are concerned about galvanic corrosion, why does this not happen between aluminum receiver and steel barrel?  This forum sports a number of home-built PCPs that appear to have raw aluminum receivers.  I have not seen them corroding.  The only aluminum corrosion I have seen has been between aluminum end caps and steel walled air tanks.  Probably from moisture in the compressed air.

I am sure the barrel will rust if rain falls on the gun and water gets between barrel and receiver.  Unless the barrel and receiver are protected by a very good passivization layer, or a hydrophobic substance, such as oil or grease.  The receiver may be anodized in the barrel socket, but the barrel would still rust if blued and left completely oil and grease free.

[MJP]

Just about any hard wax will do the job. I have used korrec car and boat wax before I bought norrslip mold releasing agent.

Marko

[subscriber]

Aluminum tape can be burnished down to pretty thin layers.

Such as this:  https://www.mcmaster.com/76145a61

[WhatUPSbox?]

Yeah, though the Home Depot HVAC aluminum tape works just fine

Note: I measured some that I put on a barrel to protect it in a chuck. It is about 3.5 mils

Also,I have not tried them but these gilding foils https://www.hobbylobby.com/Crafts-Hobbies/Stencils-Craft-Paints/Leafing/Composition-Gold-Leaf-Metal-Sheets/p/7605 are very thin. Maybe combined with a touch of spray or film adhesive.

[Nvreloader]

RKR

My Gauntlet was the same way, flopped around like a crippled goose in the breech etc.

I cured my problem by using the HVAC aluminum foil tape,
wrapped around until I found the correct diameter for a good slip fit, this tape comes in several thickness,
I miked the inside of the breech diameter, as a guide.

I have used this several times on other actions, and I have a tool made from a HD tubing cutter,
change out the cutting blade for a round smooth roller, highly polish all rollers,
then use the tubing cutter over the alum foil etc, this will tighten/compress the foil etc.

I made bands on each side of the grub screws, all the way to the end,
this seemed to work better than the epoxy, I first tried. 
Due to the thinness of the epoxy, the epoxy was easy to chip off, when fitting the bbl several times.

I did a dry fit without any "O" rings, to make sure I was as tight as needed, to just slide thru the breech,
then fit all the "O" rings and lubed every thing and slide it all together.
I went from 3"+ groups down to 1/2" groups at 40-50 yds, with OEM Crosman HP pellets etc,
and Hosp/Starling are in a world of hurt........

HTH's,

Tia,
Don

[rkr]

That sounds like a nice approach with the foil tape. I think I'll give it a go, at least it's easy to remove if it doesn't work. Good point about epoxy chipping, I was thinking about that too and that's why I had chemical metal as an option.

[Nvreloader]

rkr

I also tried a couple of other epoxies, and had the same problem with chipping,
I tried the metal tube stuff, anything under 0.010" and I had problems, on the deeper grooves It work OK.

I found that the foil worked the best, when pressed down with the roller.
When using the roller, you can squeeze the glue out when pressing the foil down etc.
When using the foil, make it as large as the tape is wide, you can then cut for the "O" rings,
thru the foil and remove it, makes it easier than making several smaller wraps etc.
Be careful with that foil tape, it is as sharp as a razor, have some band aids handy, LOL.

The foil tape comes in several thickness's, the stuff I have mikes out at .005'' and 0.0015"
alum Beer/Coke cans run right at .006" average.

The next one I get like this Gauntlet bbl, will get turned down and a sleeve fitted over the stub,
and then recut the "O" ring grooves, and proper dimensions etc..

Tia,
Don

[rsterne]

Just my opinion, but I think adding anything softer than the breech or barrel would make the situation worse, not better.... The barrel might "feel" more solid with gentle force applied.... but once the setscrews are tightened up, surely having them push the barrel over against a softer material could not be better?....

The barrel on a QB is notoriously loose in the receiver.... Once the setscrew is tightened up, it doesn't move vertically, but can shift sideways.... Here is my solution....



Note the two additional setscrews at the back of the loading tray to prevent sideways movement/rotation of the barrel.... Once the three setscrews are tight, it is rigid in all directions....

Bob

[Privateer]

Interesting thread as my .50 Sniper should be here in a couple days.
I'll have to check this.

[Hobbyman2007]

What about peening the barrel with a sharp centre punch around the circumference of the barrel in a few spots. I’ve used this method before when a bearing race spins in the bore. When peening the material that is being displaced swells around the centre punch by a few thousands. Works every time. Here’s an explanation .https://www.grainews.ca/2014/12/10/how-to-deal-with-a-loose-bearing-race/

[rsterne]

Would think that would make the barrel hard to remove, and prone to galling the receiver.... Is there no room for additional setscrews in 2 or 3 planes?....

Bob