After reading the idea of using Belleville Spring Washers to tension a barrel on the GTA (thanks, Cal), I decided to draw up something to show how it could be done.... The idea is to thread the end of the barrel (I chose 1/2"-20 NF because that is a common size for barrel attachments) and use 1/2" ID x 1" OD Belleville washers to provide an adjustable tension in the barrel to allow tuning it.... The compression load is taken by a shroud, transmitted to the breech, so the shroud has to be strong enough in compression and the barrel mounted solidly enough in the breech to stand the tension load, which can be considerable.... If, for example, you use 0.050" thick Bellevilles, they have a load when compressed flat of 600 lbs.... A stack of three of them, as shown, has a total travel of 0.075", and since 20 TPI is 0.050" per turn, if you start about hand tight (1/4 turn) and use 1 turn of adjustment, you can adjust the tension from about 100 to 500 lbs.... Here is the general idea....
The red is a bushing in the end of the shroud (blue) to take the load from the Bellevilles, it slides on the barrel (black).... The adjuster (purple) threads on to the barrel, and the Bellevilles are captive inside a chamber for appearance and to keep them clean.... You could have an index mark of the top of the shroud, and a vernier scale around the adjustment collar so that you can return to accurate settings while tuning.... There is a pair of flats machined on the adjuster so that you can use a 3/4" wrench to tighten it.... If you want more tension, just double up on the Belleville stack, (( )) (( to go from 200-1000 lbs. in that same 1 turn of adjustment.... just make sure everything is strong enough.... Different thickness Bellevilles can be used to achieve different adjustment ranges of course.... I think this is worth a try....
Bob
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