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experimental seac

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Adrian68

New Member
Oct 25, 2022
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Hi everyone, I purchased a new pneumatic gun a seac asso 90 for experimentation. The mass of the 8mm stock spear, head ,spring and slide ring was 370 grams . I had a spare chromed and threaded 7mm high carbon spear for my usual use cyrano 1100. Both ends were docked, a taper suiting the seac piston ground and a new flopper attached. A 2.5mm spearline hole was drilled 170mm back from the flopper. 1.7mm mono was passed through said hole and crimped back onto mainline, making an 80mm loop length. Total weight , 318 grams. Also, I machined and glued, a delrin 7mm sleeve to reduce the muzzle slop of the spear. This blew out on the second shot. No loss . I was interested to see this arrangement of slideless thinner spear on accuracy. The full range of the above from muzzle to spear tip was 4.8 metres. Results- (target- a golf ball size piece of shale in a sandy bottom 3 metres from muzzle) first shot hit it, second, third and fourth shots either hit it or were extremely close. I also noted the gun was much quieter. I had one tangle, I had crossed the lines when going from muzzle to line release. I thought I would try it anyway. Yep, tangle . The spear was very fast to the end of its range. An interesting experiment. I will try a stiff 1.5mm dyneema that is dipped in molten candle wax next. Cheers, Adrian.
 
If your new spear is 318 g and the old 370 g you should lower the pressure to 318/370 = 0.85 of pressure for 8 mm.
Delrin sleeve, glued, can not withstand the pressure of water escaping from the muzzle forward.
You would have still better performance if you were using 1.1 mm Dynema.
 
Hi everyone, I purchased a new pneumatic gun a seac asso 90 for experimentation. The mass of the 8mm stock spear, head ,spring and slide ring was 370 grams . I had a spare chromed and threaded 7mm high carbon spear for my usual use cyrano 1100. Both ends were docked, a taper suiting the seac piston ground and a new flopper attached. A 2.5mm spearline hole was drilled 170mm back from the flopper. 1.7mm mono was passed through said hole and crimped back onto mainline, making an 80mm loop length. Total weight , 318 grams. Also, I machined and glued, a delrin 7mm sleeve to reduce the muzzle slop of the spear. This blew out on the second shot. No loss . I was interested to see this arrangement of slideless thinner spear on accuracy. The full range of the above from muzzle to spear tip was 4.8 metres. Results- (target- a golf ball size piece of shale in a sandy bottom 3 metres from muzzle) first shot hit it, second, third and fourth shots either hit it or were extremely close. I also noted the gun was much quieter. I had one tangle, I had crossed the lines when going from muzzle to line release. I thought I would try it anyway. Yep, tangle . The spear was very fast to the end of its range. An interesting experiment. I will try a stiff 1.5mm dyneema that is dipped in molten candle wax next. Cheers, Adrian.
1) Delrin is practically non-glueable
2) 2.5mm spearline hole is too big as well as 1.7mm mono. I'd use no more than 1.5mm mono at most
3) Unless you put a chamfer on the both sides of your spearline hole I am afraid the line would be eventually damaged
4) Interesting that the accuracy was not compromised
 
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If you use the search feature then you will find these aspects have all been evaluated before, different spear and shooting line diameters, etc.
 
1) Delrin is practically non-glueable
2) 2.5mm spearline hole is too big as well as 1.7mm mono. I'd use no more than 1.5mm mono at most
3) Unless you put a chamfer on the both sides of your spearline hole I am afraid the line would be eventually damaged
4) Interesting that the accuracy was not compromised
Hi Vrokhlenko, yes, delrin is slippery. The 2.5mm hole is too big indeed. It was the smallest carbide bit I had. I did wonder about the scraping effect of passing through fish scales, bone, reef etc. I will build a proper target for testing also. The ranges I shoot reef fish at are usually less than 3 metres and the fish 2 - 6 kgs so I will evaluate accuracy further . Thanks.
 
Hi Vrokhlenko, yes, delrin is slippery. The 2.5mm hole is too big indeed. It was the smallest carbide bit I had. I did wonder about the scraping effect of passing through fish scales, bone, reef etc. I will build a proper target for testing also. The ranges I shoot reef fish at are usually less than 3 metres and the fish 2 - 6 kgs so I will evaluate accuracy further . Thanks.
There is no need for a carbide bit drilling into a tempered shaft. Cyrano shafts are made from a 17-4 steel in H900 temper and can be drilled by a quality HSS drill bit slowly with plenty of lubrication. Ofcourse a drill press is a must
 
If your new spear is 318 g and the old 370 g you should lower the pressure to 318/370 = 0.85 of pressure for 8 mm.
Delrin sleeve, glued, can not withstand the pressure of water escaping from the muzzle forward.
You would have still better performance if you were using 1.1 mm Dynema.
Hi Tromic, I actually put another 20 pumps in the chamber. Oh, well. I also intend to use 7x7 stainless 1.2mm diameter , 316 for the spear
attachment and then join on stiff dyneema. It may solve the abrasion through fish problem. Thanks.
 
There is no need for a carbide bit drilling into a tempered shaft. Cyrano shafts are made from a 17-4 steel in H900 temper and can be drilled by a quality HSS drill bit slowly with plenty of lubrication. Ofcourse a drill press is a must
Hi , You are correct. This shaft, however , is 25 years old and definitely black steel and hard as the hobs. cheers.
 
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