30" .22
Heres the progress so far on my 30″
still building the silencer for it
all of these mods are eventually destined for the bullpup frame with a 4500psi carbon tank
the idea of this is to test how well those 30grain boat tail solid pellets do when pushed supersonic
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The new bushing replaced the old bushing in the same position.
The new bushing was not any where near the end of the barrel.
I think Leupy is correct, the barrel must float.
The shroud is aluminum.
The barrel is steel.
Aluminum expands 3 times faster than steel with changes in temperature.
If you constrain the end of your barrel in the endcap, thermal expansion may mess up your accuracy.
I am not sure that I explained that well?
I would avoid using more than 2 bushings.
My bushing improved accuracy by stoping the barrel from viabrating.
Like putting your hand on a bell to stop it from ringing.
Mark
I get what you’re saying, but the two bushes in the frame are aluminium. How come they don’t mess up the accuracy by the same process? I can’t see why another bushing (an endcap) would make any difference simply by virtue of it’s position? With heavy recoil and a barrel that flexes it would make more sense.
I’ll have to satisfy my own curiosity and give it a go. I suspect it won’t make any difference either way but maybe I’ll learn something new. 🙂
still building the silencer for it
all of these mods are eventually destined for the bullpup frame with a 4500psi carbon tank
the idea of this is to test how well those 30grain boat tail solid pellets do when pushed supersonic
Strewth m8, that is a barrel and a half! Nice though
Langnasen:
The new bushing replaced the old bushing in the same position.
The new bushing was not any where near the end of the barrel.
I think Leupy is correct, the barrel must float.
The shroud is aluminum.
The barrel is steel.
Aluminum expands 3 times faster than steel with changes in temperature.
If you constrain the end of your barrel in the endcap, thermal expansion may mess up your accuracy.
I am not sure that I explained that well?
I would avoid using more than 2 bushings.
My bushing improved accuracy by stoping the barrel from viabrating.
Like putting your hand on a bell to stop it from ringing.
Mark
One of my homebuilt guns has a long, thin barrel, like your setup.
It took me forever to get it to shoot accuratly.
It turned out that the barrel was viabrating, like a plucked guatar string, when it was shot. It would throw one shot to the right the next one came in low, the next high,etc. It shot 3+ inch groups at 50 yards.
I fixed the problem by building a 3 inch long front bushing. The close fitting, long, plastic bushing damped out the viabrations.
Accuracy went from 3+ inch groups to dime sized groups right after installing the new bushing.
I see your setup is like mine.
If you have trouble with accuracy, think about barrel viabrations.
Mark
This was something I asked Leupy to do, but he said if the end-cap contacts the barrel it would reduce accuracy as the barrel needs to be floating. 😕 As far as I can see it would be just another bushing, effectively.
My next job is going to be a long end-cap, tolerance-fit to the barrel, and I’ll see how it shoots.
Thanks Mark ill bear that in mind
i had considered that it could be an issue as you obviously did as well
i was thinking of making the frame/shroud to come past the end of the barrel and support the bbl with some extra bushings as it is in the main frame
colinb:
One of my homebuilt guns has a long, thin barrel, like your setup.
It took me forever to get it to shoot accuratly.
It turned out that the barrel was viabrating, like a plucked guatar string, when it was shot. It would throw one shot to the right the next one came in low, the next high,etc. It shot 3+ inch groups at 50 yards.
I fixed the problem by building a 3 inch long front bushing. The close fitting, long, plastic bushing damped out the viabrations.
Accuracy went from 3+ inch groups to dime sized groups right after installing the new bushing.
I see your setup is like mine.
If you have trouble with accuracy, think about barrel viabrations.
Mark
yeah part of the testing is going to be whether it needs to be supported within the silencer/extended frame
it is long yes but then again i am 6’5 so it doesn’t seem too bad for me
and in the bull pup configuration it will be no longer than your standard stealth/talon
i don’t have any fps figures yet but i have managed to push a solid 30grain into super sonic
specs on bbl
Walther .22 Barrel Blank, 755mm long x 10mm Diameter. 1-17 Twist rate, 8 groove.
Yeah, why make that a barrel? Just sharpen the end. 😛
Definately not going for the compact design. Seems like that barrel would bend sticking out that far without support.
You don’t need to shoot at the squirrels with that, you can just poke them out of the tree 😀
FPS fiqures should be interesting… 😮
What diameter has that barrel??
Regards,
Marc
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I’ll have to satisfy my own curiosity and give it a go. I suspect it won’t make any difference either way but maybe I’ll learn something new. 🙂
Think about what happens when you press on a guitar string at a frett as opposed to the whole string vibrating…
The sound changes because the strings vibration frequency and period changes…
Think of the barrel like the string, 24″ of unsupported length vs. 20″ of unsupported length….
Which one will move less? 😉