Why I recommend hand Crowning Barrels

[rsterne]

If the bore is offset in the middle by half the caliber (ie looking through it, you only see half the other end), which is highly unlikely.... for a .22 cal barrel that is 24" long, the error would only be about 0.002" at the muzzle, if you machined square to the outside.... half the thickness of a piece of paper.... I doubt our pellets have the skirts within that level of accuracy.... For practical purposes, with a 90* crown, square to the outside is "good enough".... That is NOT the case if the bore is off center and you machine the crown on an angle in a lathe, ie cutting an 11* "target crown".... which is the point of this post....

Bob

[K.O.]

For a $100+ dollar barrel that is pretty bad imo...

Now if it was a larger caliber and meant for say the new .25 JSB Heavies at 800-950 fps I think I would worry about possible harmonic probs...

But for a .177  up to about 20 fpe  I think I would just make sure it is lined up with the offset on the vertical... I would not like it, but on that nice thick barrel probably not much effect if any...

[QVTom]

Right on point Michael.

I hand crown my barrels and use a piloted reamer for the chamber/leade.  Barrels are checked for concentricity with a gauge pin, faced at 90*, and crowned with a stone and then a brass ball with 320 grit.  If a barrel has more than 0.002 runout, which is rare for a TJ liner, I'll dial it in before facing.

The barrel in the vid is typical LW but worse than most I have experienced.  I think airgunners are so used to cheap barrels that LW has become quality go to.  In reality they are just a decently made barrel and far from the quality a true match barrel.  Unfortunately they are the only real players in the AG market; with the lack of competition they seem content to deliver what they deliver.

Tom

[Wayne52]

Especially after watching the video shows exactly why you would want to crown it on a lathe. Kinda makes you wonder exactly what method they used when making the bore.

[K.O.]

I am pretty sure they use D.O.M. tube just like Crosman... They may have taller rifling and switch out the button quicker and maybe a different alloy

but

their sight does say tubing...

http://www.lothar-walther.com/454.php

[MichaelM]

lol the point of the video was to point out WHY a barrel should be hand crowned and lapped.....

that being said.... in reality there isnt anything really "wrong" with the barrel ( though maybe I WILL send an email to LW for the giggles just to see what happens but after waiting 4 weeks for a reply the last time I highly doubt they will even send a reply...)

as far as quality goes.. LW uses a DOM tubing then its bored.... then button rifled...  try boring a slightly smaller then .177 hole through multiple feet of tubing then pulling a button through it and see how much the tooling will wander along the length of tubing...

Now... I will admit this is what I would consider to be WORST of the acceptable off centers it will still shoot straighter then any of us mere mortals can hold ....  and unless I was building a 20 pound benchrest gun I will never know the difference(and then again I wouldn't be using a 112 dollar barrel if I was...)
ALSO remember button riffling is far different then a hammer forged barrel like TJ's.... trust me if he made a .177 I would never have looked at LW in the first place especially if he offered a polygon riffled setup.....


think bob did a good job of pointing out the extremes that a barrel can be and still be accruate plus his math on the effects are also a great example.... I mean.. can any of you tell a difference odf a couple hundredths of an inch at 100 yards??? I know i sure cant....

[mobilehomer]

I was speaking of the off-center muzzle as it pertains to threading for accessories, not as to accuracy or consistency. If the accessory is off center to the muzzle, the pellet will clip.
Geometry, if the bore is centered at the breech end and off center at the muzzle as much as in the picture - the bore is angled for the whole distance! Having machined 24" and longer holes, with a .001 I.D. tolerance, with a pin gage to check it with, I have experience with a drill not running parallel to center, but still be straight.

[QVTom]

lol the point of the video was to point out WHY a barrel should be hand crowned and lapped.....

that being said.... in reality there isnt anything really "wrong" with the barrel ( though maybe I WILL send an email to LW for the giggles just to see what happens but after waiting 4 weeks for a reply the last time I highly doubt they will even send a reply...)

as far as quality goes.. LW uses a DOM tubing then its bored.... then button rifled...  try boring a slightly smaller then .177 hole through multiple feet of tubing then pulling a button through it and see how much the tooling will wander along the length of tubing...

Now... I will admit this is what I would consider to be WORST of the acceptable off centers it will still shoot straighter then any of us mere mortals can hold ....  and unless I was building a 20 pound benchrest gun I will never know the difference(and then again I wouldn't be using a 112 dollar barrel if I was...)
ALSO remember button riffling is far different then a hammer forged barrel like TJ's.... trust me if he made a .177 I would never have looked at LW in the first place especially if he offered a polygon riffled setup.....


think bob did a good job of pointing out the extremes that a barrel can be and still be accruate plus his math on the effects are also a great example.... I mean.. can any of you tell a difference odf a couple hundredths of an inch at 100 yards??? I know i sure cant....

I think you missed made and my point  .  Nothing is expected of LW (your case) and they don't seem to want to stay on their game.  I realize it will shoot fine but as a builder you deserve better.  working with wonky barrels only serves to burn up valuable time.  Ever ask for specs. from LW?  Good luck.

Tom

[MichaelM]

I think you missed made and my point  .  Nothing is expected of LW (your case) and they don't seem to want to stay on their game.  I realize it will shoot fine but as a builder you deserve better.  working with wonky barrels only serves to burn up valuable time.  Ever ask for specs. from LW?  Good luck.

Tom

LOL Most that information was in there for general education of people who may not understand and think the barrel was atrocious because of the wobble....


that being said I absolutely agree with you LW doesnt care AND quality control seems to have fallen by the wayside for the airgun stuff(even though thats what they made their name in...)

Ugh if we could only get mike to do a .177 tj liner.... even have a great idea for a progressive twist poly rifled barrel with a really slow 1 in 24 or even 36 twist... which I wold almost bet would be super awesome with pellets.........

[MichaelM]

ALSO!!! thank you everyone for the great responses to this thread!!! I absolutely appreciate everyone's input!!!

[MichaelM]

Also... emailed LW today about how badly off center the bore is on that barrel....

"So.... I get my barrel after a 4 week wait of non communication or updates and this is the quality of the barrels your putting out now... I can honestly say this is probably the last LW barrel I will ever own... I haven't seen a bore this off center even on cheap china imports..... Oh well I guess it makes a good video of why a person should hand crown and lapp a barrel.... though I would forget trying to put a shroud or a brake on this thing.....

  "


should we start a pool on how long it takes for a reply?

[Scotchmo]

It looks like you crowned the stamped end of the barrel. Are you sure that was the choked end? Did you push a pellet down the barrel to confirm the choke?

[MichaelM]

It looks like you crowned the stamped end of the barrel. Are you sure that was the choked end? Did you push a pellet down the barrel to confirm the choke?

The stamped end was untouched and as it was removed from the bag....  The end in the Chuck that I videoed is the muzzle end with just a square up pass made....

From what I gathered is the stamped end is the breach and pushing pellets proved this to be correct.....

[MichaelM]

Update....  I have decided I am machining the blank down to 14 mm then getting 14mm carbon fiber tubing and sleeving the barrel....  Bringing it back out to a 15 or 16 mm diameter depending on the CD tubing I pick up....  I indexed off the bore and the bore was off center by a touch over .007 .... 

[Tater]

If you make another video, maybe one showing how you hand crown that barrel and what products you use?