HW 50 Accuracy improvement by accident

[hunkaluv]

Hi all,
I set up this little hw50 as a lightweight shooter for WFTF Field target for my dad. I was going through some pellet testing today and wasn't having much success. Indoor, 10 yard, benched on sandbags and i couldn't get anything to group tighter than about 3/8. To make the cocking a little easier, i installed a carbon fiber tube which is much longer than the barrel. (I never measured, but probably about 9" longer.) The tube is just held in place by a half dozen orings that are slipped over the top of the barrel, then i pushed the tube onto the barrel. The groups went from 3/8" to 1/4" (which is acceptable for a springer on a bench imo). I removed the shroud a few times and tested with and without the shroud. Always the same, 3/8 no shroud, 1/4 with the shroud. There's nothing in the shroud from the end of the barrel to the end of the shroud. So, what the heck has happened here?
I figure it's either improved harmonics, or the carbon fibre tube is somehow acting like an air stripper. Either way, the tube is staying! I'd be interested to hear some theorycrafting as to why this happened.

HW50 177, Vortec 4 kit installed, running JSB 844 at 685fps for 8.8fpe. (Yes it's a bit low for FT, but it's a sweet shooter at that energy level, and easier to cock.)

Ryan

 

[cavedweller]

Hi all,
I set up this little hw50 as a lightweight shooter for WFTF Field target for my dad. I was going through some pellet testing today and wasn't having much success. Indoor, 10 yard, benched on sandbags and i couldn't get anything to group tighter than about 3/8. To make the cocking a little easier, i installed a carbon fiber tube which is much longer than the barrel. (I never measured, but probably about 9" longer.) The tube is just held in place by a half dozen orings that are slipped over the top of the barrel, then i pushed the tube onto the barrel. The groups went from 3/8" to 1/4" (which is acceptable for a springer on a bench imo). I removed the shroud a few times and tested with and without the shroud. Always the same, 3/8 no shroud, 1/4 with the shroud. There's nothing in the shroud from the end of the barrel to the end of the shroud. So, what the heck has happened here?
I figure it's either improved harmonics, or the carbon fibre tube is somehow acting like an air stripper. Either way, the tube is staying! I'd be interested to hear some theorycrafting as to why this happened.

HW50 177, Vortec 4 kit installed, running JSB 844 at 685fps for 8.8fpe. (Yes it's a bit low for FT, but it's a sweet shooter at that energy level, and easier to cock.)

Ryan

View attachment 461990

View attachment 461991

I’ll assume it’s behaving like an air stripper AND a vibration dampener

 

[BenjaminM]

That’s interesting, I have a friend who had a hunting rifle that just wouldn’t group…after working through everything else finally he took a torque wrench to the bolt holding the action to the stock. He found a specific torque where all the sudden it started stacking rounds. The only thing he could figure out was it affected the barrel harmonics somehow….

 

[Hold_Over]

How far does the cf tube extend past the muzzle?

 

[BeMeUp]

I read the same thing about fx barrels if you don’t want to buy the carbon fiber sleeve half dozen o rings stiffen up the barrel wobble

 

[hunkaluv]

How far does the cf tube extend past the muzzle?

7.5" past the end of the muzzle.

 

[hunkaluv]

I read the same thing about fx barrels if you don’t want to buy the carbon fiber sleeve half dozen o rings stiffen up the barrel wobble

Interesting, that's why i had some carbon fiber tubes on hand, to experiment with on my FX Dreamline.

 

[Green_Yamo]

Very cool, thanks for posting this! Gorgeous stock BTW.

 

[RickH]

Beautiful rifle. I suspect it’s a harmonics problem, something could just be a little loose or slightly over torqued.
Rick H.

 

[elh0102]

Whether harmonics or air turbulence control, it worked. Sometimes great things are achieved through hard work and perseverance. And sometimes the blind hog finds an acorn. Claim the former and enjoy the latter!

 

[hunkaluv]

Very cool, thanks for posting this! Gorgeous stock BTW.

Thank you! It's made from a walnut tree that was growing on top of my father in law's septic tank. It's loosely copied from my own personal favourite stock, a a GinB.

 

[Green_Yamo]

Thank you! It's made from a walnut tree that was growing on top of my father in law's septic tank. It's loosely copied from my own personal favourite stock, a a GinB.

Wow, homemade - VERY NICE!!!

 

[gdc999]

If I understand correctly, the O-rings go on the barrel then, the sleave goes over the O-rings. I would be curiosity to know how it shoots if you just put the O-rings on the barrel and leave the shroud off. The O-rings might be acting to change the harmonics like the old "decelerator" donut was supposed to do.

 

[JP806TX]

If I understand correctly, the O-rings go on the barrel then, the sleave goes over the O-rings. I would be curiosity to know how it shoots if you just put the O-rings on the barrel and leave the shroud off. The O-rings might be acting to change the harmonics like the old "decelerator" donut was supposed to do.

I assume the OP will handle the barrel a lot cos it's a break barrel.

How's the O-ring going to precisely stay in place without the CF shroud?

To counter act the harmonics don't the O-rings need to be in a precise area of the barrel? (I assume there's more than one O-ring)

Glue the O-rings on?

Sorry didn't mean to throw a wet blanket on this idea. Still might work without the CF shroud.

 

[hunkaluv]

If I understand correctly, the O-rings go on the barrel then, the sleave goes over the O-rings. I would be curiosity to know how it shoots if you just put the O-rings on the barrel and leave the shroud off. The O-rings might be acting to change the harmonics like the old "decelerator" donut was supposed to do.

Correct, the o rings slide onto the barrel (about 6 if i recall correctly) then i slid the CF tube over top. When i removed the tube a few times to check with and without the tube, i left the orings in place on the barrel. Even with the orings in place (and no tube) the groups still opened up to the original size. (Without orings and tube.)