Challenger LW Barrel

[FuzzyGrub]

Was looking for an easy way to get a LW barrel to fit an Mrod, by trying the crosman Challenger barrel. Well, probably not so easy.

Length: 21 9/16"
Diameter: 0.432" vs 0.435" for Mrod. It is a loose fit in the CF tube
TP: is 1377 style and would need to be machined for Mrod style
TP hole center is closer to breach end: About 0.230" vs 0.300" of Mrod
Flats: Has two at each end, and do not line up with Mrod breach set screws, but that isn't much to make flats where needed

Pushed some jsb pellets through it, better riffling marks than the stock Mrod.
It is choked and feels slightly tighter going through with pellet than Mrod.

[SHOOTINIT]

Diameter: 0.432" vs 0.435"


well that sucks

[Motorhead]

Had done one for a club member ...
Did a thimble type end cap for breech o-ring / transfer hole.

Single wrap of cellophane tape fore & aft where barrel is in contact with receiver bore snugged up the fit.

We found it odd that barrel shot good but not great at near 20 ft lbs power, but extremely well closer to 12-14 lb range with 8.4 or 10.3 weight JSB's.
Never chased down the challenger barrels twist rate or land/bore sizes trying to figure out the why ? .... owner of gun purchased a .630 LW blank and we fit it to rifle via thimbling also and it shot great !!

Your results may differ

Scott

[FuzzyGrub]

Had done one for a club member ...
Did a thimble type end cap for breech o-ring / transfer hole.

Single wrap of cellophane tape fore & aft where barrel is in contact with receiver bore snugged up the fit.

We found it odd that barrel shot good but not great at near 20 ft lbs power, but extremely well closer to 12-14 lb range with 8.4 or 10.3 weight JSB's.
Never chased down the challenger barrels twist rate or land/bore sizes trying to figure out the why ? .... owner of gun purchased a .630 LW blank and we fit it to rifle via thimbling also and it shot great !!

Your results may differ

Scott

Well, that's not encouraging!

Maybe just for curiosity sake, but would like to hear more about the thimble. Did you machine the barrel down using stock length or cut the first 1/2" or so off, then machine for thimble?

[Motorhead]

Yea, cut barrel off right at original transfer hole and then turned the O.D. down to a stub @ 1" or so in length. Cut in a recess on face for the o-ring centering & depth. Also removed rifling ( Lead ) in @ 1/8" for bolt probe clearance at breech closure time. Wanted pellet FULLY in the rifling.
Bored an oversize aluminum sleeve ( Thimble ) a few thousands smaller than barrel stub to a depth exactly that of stubs length, drilled the end for bolt probe clearance and faced it off so the breech end to surface o-ring rests was @ .080" thick. Then pressed the thimble onto the stub. From there using a live center in the lathe tail stock turned the thimbles diameter down to that of barrel. Drill and spot face transfer passage in the milling machine, deburr and your done !

[FuzzyGrub]

Scott, thx for the detail. I don't have the equipment or skills to pull that off. and then the possibility of not being accurate at the fps I want. Looks like I will be returning it.