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Tomba - All in One barrel sealing

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
[ame=http://www.youtube.com/watch?v=WIRxCvm-X3A]Tomba kits - YouTube[/ame]
 
Good to repeat some facts about Tomba:

[ame=http://www.youtube.com/watch?feature=player_embedded&v=scN5N84Tv0I]Tomba10 - demonstration - YouTube[/ame]
 
Maybe this would be a solution to reduce friction during loading, if shaft is bending.
Making this modification might allow 4 x more bending of shaft than now. Might help!






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Last edited:
Here is a tiny modification to slider that could make loading easier if bending the spear during loading.

 
Allowable radius of bending the spear during loading might be 60 cm.
This would add some comfort to beginners not used to proper loading technique.
 
What happens when bending the spear during loading?
In case of "B" more bending is possible, but water might enter the gun.

 
I think it is better to concentrate on pushing the spear in as straight as possible rather than allowing any compliance for bending at the muzzle entrance. Side to side rocking of a plastic slider in the muzzle may eventually wear down that larger diameter rearmost "ring" as less material there will be interacting with the well in the muzzle, so the slider may eventually becomes a loose fit in the muzzle bore. It is possible to bend a spear tail permanently a few centimetres up from the rear end if you don't push the spear in as straight as possible because I have done it. Then the spear had to be straightened out to get rid of the kink, albeit a very small one (it was a standard Mares spear, not a spring stainless steel spear).

Under hard muzzle loading a spear usually develops a slight bow that does not result in a permanent set, the flexing is spread all along the length of the shaft, but concentrate the bending action near the rear end and you can put a kink in a spear because you are working a long lever arm against the muzzle as you pull the loading handle off to one side.
 
This is an idea for flexibile Tomba adapter. Also loading in water would be possible.

 
Here is an O-ring calculator I made for Tomba.
The most important value is O-ring compression on excentrity of the shaft (during loading). It is the worst case scenario, when the shaft OD is at min, Cone ring ID at max, O-ring CS at min, Tomba adapter boring ID on max. That value should be possitive or flooding may happen.

https://www.dropbox.com/s/wln9sdja5sxksqi/OringCalculator.xls
 
I just got an idea how could be a new Tomba slider the most hydrodynamic, maybe even more hydrodynamic than the elder one with neck to tie mono on it. What I am not sure how secure would it be this way?

 
Reactions: Jegwan


This adapter might be easier to make:



Left part is in aluminum, right part in ertacetal. Loading of the shaft might be easier because allow some bending during loading.
 
This modified, flexible adapter should allow deviations of spear during loading to near 3 (2.5 + 0.5) degrees from the central axis. Now it is about 0.5 degrees. I think it would greatly facilitate loading, especially for those whose technique is not yet perfected. Such is certainly at least 70%. There is a simpler solution - draw a slider little from the head after a pushing the O-ring into the muzzle. This way, possible deviations from the central axis would be slightly less than 2 degrees. But in this case there would be a chance that at extreme flexing a little water may enter the rifle. This could happen if the thickness of the O-ring is smaller than the nominal value (2.5 mm - 0.1 mm) or if the hole in the cone ring were higher by more than 0.1 mm from the shaft thickness . Flexible adapter would be better, but more complex solution. However it would reduce the overall reliability of the system due to the additional O-ring. Moreover with a new adapter rifle might be quieter because sound wuold be little muffled with the extra O-ring.
 
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