Pneumatic Spear Compatibility

[PezGordo]

Hello all,
I am a new member located on the West Coast of Ecuador. I just purchased (not received yet) a Salvimar Rock 40 to be used in our pretty well constant low visibility, shallow coastal inlets. The seller of the speargun was out of stock of spare spears, I would like to purchase a couple of spears (local resources are scarce) thus ordering via mail order is the only option.
Before ordering, here is my question, the Rock uses an 8mm threaded shaft, is it possible to substitute a shaft of another manufacturer, for example this:

"Spear threaded stainless steel Seac sub for Asso speargun pneumatic tyres Ø 8 mm"

https://www.nootica.com/spear-threaded-stainless-steel-seac-sub-for-asso-speargun-pneumatic-tyres-o-8-mm.html

I understand that one or both "ends" of the pneumatic spear shafts, the threaded tip and the part that enters the barrel are threaded on, and (may) be removable, is this correct? If not, is there a major difference between 8mm shafts of different manufacturers in regards to the end contacting the piston, such as "spear tail stop, metal "fence" and/or shock absorber design or are the shafts interchangable?
One more question, the 8mm shaft of Salvimar Rock, what is the tip thread size, (M7?), can sombody please confirm this?
Appreciate all replies, thank you kindly.

 

[vrokhlenko]

 

[vrokhlenko]

If the end of your spear looks like this - get it

 

[PezGordo]

If the end of your spear looks like this - get it

Thanks, for the reply. I did not receive the item yet, here is a picture of the spear from the seller website. Looks similar, same??

 

[vrokhlenko]

Look, the purpose of this conical surface at the end to provide tight fit when loading the gun. So the spear would be connected to the piston via friction. In my opinion they are all the same. If you load the gun with a non-salvimar shaft and it would be sliding out (which is HIGHLY UNLIKELY) all you would need is to get those salvimar end-pieces for an 8mm shaft and replace with them the ones on the cressi shaft. Based on this: https://maverick-america.com/salvimar-butt-adapter-for-vintair-cyrano predathor, vintair and cyrano use the same butt. Do some research - if cressi and cyrano butts are interchangeable - get them

 

[PezGordo]

Look, the purpose of this conical surface at the end to provide tight fit when loading the gun. So the spear would be connected to the piston via friction. In my opinion they are all the same. If you load the gun with a non-salvimar shaft and it would be sliding out (which is HIGHLY UNLIKELY) all you would need is to get those salvimar end-pieces for an 8mm shaft and replace with them the ones on the cressi shaft. Based on this: https://maverick-america.com/salvimar-butt-adapter-for-vintair-cyrano predathor, vintair and cyrano use the same butt. Do some research - if cressi and cyrano butts are interchangeable - get them

Great info, thank you, appreciate your comments. It appears that Salvimar and Asso 8mm shafts are interchangable.