XS60C PCP Repeater project

[RHytonen]

Bob, if I didn't respect your opinions so much I wouldn't bother to discuss them.
It's really OK to disagree on one thing - especially esthetics.

And I have done considerable homework on this liner thing since Eric suggested it, as I do like (OK, need,) to save money My opinion includes that, and even its adopters give a considerable nod to resonance issues but don't address concentricity (re: the entire process,) and I don't have affordable access to a lathe to correct or adjust that. So IMO I'm better off taking a shot for +/- (sometimes way less than)$100 at gettting lucky with a purpose built, one piece, heavy, final product barrel.
YMMV of course.

[stalwart]

Dissimilar materials in laminate can go a long way to damping harmonics.

I'm leaning toward aluminum bull barrels with the smallest OD liners possible, for the hunters. Coat-able, light, and stout.

[RHytonen]

Dissimilar materials in laminate can go a long way to damping harmonics.

I'm leaning toward aluminum bull barrels with the smallest OD liners possible, for the hunters. Coat-able, light, and stout.

You may have something there with Aluminum... depending on the hardening,(or lack of,) its softness might help the resonance thing. Then there's brass to try....
I admit my assumptions always (but sometimes inappropriately)start with CrMO... I use so much of it for racing stuff. I'd still stay with the thickest liners though, personally.

Lots of fun (but expensive) experimentation possible.

(again just my airgun-inexperienced but educated engineer's guesses...having long abandoned the math of my BSEE  through experience in the superiority of 60 pro yrs. of 'gut feelings,' which reality will so often inconveniently provide. The saviour there is accompanying artistic talent.

And I was taught early on, (in 3rd grade English,) disclaimers on one's statements as opinion are NEVER necessary nor appropriate.
If anything one says or writes is NOT "(just) his opinion," and he didn't footnote or otherwise attribute it to the originator, he is a plagiarist.
To assume otherwise (by expecting his statements to include said apology) is therefore to accuse him of possible plagiarism. "JMO," is therefore redundant and never necessary.
Rod

[StevenG]

Dissimilar materials in laminate can go a long way to damping harmonics.

I'm leaning toward aluminum bull barrels with the smallest OD liners possible, for the hunters. Coat-able, light, and stout.

If you are still considering an oval shroud, would it be possible to use the smallest OD liner and support it only with some baffles?

[rsterne]

I would think that using a very small OD liner which is not continuously supported by bonding it into a larger, rigid barrel would be a recipe for additional nodal vibrations between the supporting baffles.... and the slimmer the liner the more pronounced the effect.... Tensioning the barrel by putting the shroud in compression with a threaded fitting at the muzzle will raise the resonant frequency of the vibrations, both primary and secondary, in a similar way to increasing the OD of the barrel....

Bob

[stalwart]

As it sits now, the shroud set up would be attached to a barrel that is just small enough to be forced into the oval, and it would be bonded full length, top and bottom. The baffles will be bonded in at the same time.

Time, and the cost of experimenting with high temp resins are what's holding that up. I have that, and a couple more ideas to try... as soon as the basics are covered.

[StevenG]

As it sits now, the shroud set up would be attached to a barrel that is just small enough to be forced into the oval, and it would be bonded full length, top and bottom. The baffles will be bonded in at the same time.

Time, and the cost of experimenting with high temp resins are what's holding that up. I have that, and a couple more ideas to try... as soon as the basics are covered.

Now that is a unique arrangement. Exciting stuff.

[RHytonen]

No idea what the "choke" comment is about.... and while I agree that stiffness in a rifle barrel is critical, you won't convince me that straightness is....

If you are referring to Carbon Fibre as a "plastic" you are sadly mistaken.... only the glue that holds it together is a plastic.... CF is stronger and stiffer than steel, and a LOT lighter.... If a 9/16" steel barrel isn't heavy enough for you, then purchase a piece of steel tubing of that ID and as large as you can get OD and solder them together (since you don't like glue).... It's a great way to make a match quality barrel....

and, if you don't like my suggestions, then ignore them, I have no problem with that....

Bob

Trying to heat and solder all 360 degrees and the entire length of a 36-41" long tube at the same time , with home equipment (a torch, or torches) sounds pretty daunting... Doing (and cooling) it evenly, sounds impossible. They don't guarantee the wall thickness/ID tolerance of commercial, even aircraft, steel tube; to be all that uniform either... which is an issue whether you use glue or solder.

Rod

[rsterne]

The typical procedure in bygone days for installing a .22 liner in a CF rifle barrel was to drill it out about 0.010" larger than the OD of the liner, tin the liner, tin the inside of the barrel, start the liner into the preheated barrel and heat the barrel with it vertical and watch the liner just slide down into place from gravity.... My Dad did one, I shot it for years.... He told me that skilled shooters used to make .22LR target rifles from worn out CF barrels that way all the time.... and they shot better than most purpose made .22LR target barrels....

Bob

[RHytonen]

Wouldn't you have to be equipped as a barrel machine shop anyway to drill something 36-41" long accurately?

[rsterne]

Actually, my Dad brazed a 5/16" (or slightly bigger) twist drill to a piece of 1/4" steel rod about 24" long and used that to drill the barrel.... no lathe, either.... I didn't see him drill it, but we had the drill kicking around years later.... I think he started with a .303 British, so about all he had to do was clean out the rifling.... I know the liner was a very thin wall, I always got a kick out of looking at the muzzle and seeing the liner and barrel with a line of solder in between.... That barrel shot as good as any .22 LR I have ever shot....

Bob

[RHytonen]

"dang" you Bob.
You actually have me thinking of trying it..
You are a very bad man.

(J/K - Rod.)

[RHytonen]

& "nanny s/w" is incredibly lame here.
4shame.

[rsterne]

Sometimes things aren't as tough, or complicated as you think....

Bob

[stalwart]

You are a very bad man.

I have been trying to warn everybody about Bob, but no one will listen!   

Seriously, Rod... how proud would you be of a barrel you put together?

[RHytonen]

LOL that would depend on whether I could hit the garage with it at 20 feet
Of course, if I make it long ENOUGH.....   (to throw like a spear)

BTW the plugs look GREAT!
(They came today.)

now to start watching eBay for rusted-out Muzzleloader bbls.
People tend to sell only the ones that look usable.

[stalwart]

Now, you're talkin'.

 

[RHytonen]

Now, you're talkin'.

 

Woke up this morning envisioning a machined Al collar (if I had a lathe) with 3-4+  setscrews and drilled depressions in the breech end of a barrel (will get turned down eventually) - to hang it from... with heavy steel wire. (what if it melts first? OK, steel rod. Fireproof triangle rig? Gotta support the liner straight until it drops, too..)
Some things are NOT simpler than they sound....

Need a better description from Bob's memory  (mining his dad's experience) obviously.
 Rod

[stalwart]

Got some .30 cal mags in from Lloyd at Airgun Lab. Slick! Does anyone smell something cooking?

I promised this would be a fun winter! 

[stalwart]

Oh, and Rod... the guy who taught me to machine used to say "With every project, there comes a time when it's best to shoot the engineers, and go into production".

(J/K)