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All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

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Old 09-09-2003, 07:27 PM   #1
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The ballistics of 9/32" Vs 5/16" Vs 3/8" shafts


I was reading a post from Copino on the effective range of a speargun he was asking.

I look at my old post at Deeper Blue and found something which might interest many of you.

I posted sometime last year and since I spent so much time testing the 3 shafts, I want to post it here to make it more useful for the new shooters or anyone into experimenting the speargun ballistic.

Here goes.........

I had one hour to test and was putting power output as a priority. Have not had time to test accuracy. As promised here are my findings based on spec below.

Riffe Metal Tech #0 at 81 cm or 32". Floater wing and aluminum muzzle. 5 x 9/16 bands at 15".

This gun is a natural sinker in standard form with the plastic muzzle. The floater wing kit is supposed to make it float. Since I used the extra heavy aluminum muzzle, it becomes an extra sinker. What did I find out ? Even with the floater wing, this gun is still a sinker cause of the aluminum muzzle. With 5 bands in sea water, it sinks super slow (shaft out ) like maybe 3 seconds a feet. I was curious and removed two bands, it sink even faster. Bands are quote buoyant, I just remembered that.

Shaft tested 9/32" (7mm) Hawaiian at 34" with 270 lbs coated stainless shooting cable at 380cm ( 12.6 feet ). Second shaft at 5/16" (8mm ) x 32" using Riffe large spearhead, same shooting line set up. Maximum shaft to target reach with this set up is 380 cm + 60 cm = 420cm ( 14 feet ) from muzzle. Testing range was about 380 cm muzzle to 6mm (0.23") plywood board. The original setting of shooting line is 2 wraps, mine is at 3 wraps.

9/32 / 7mm shaft TEST
I first shoot at nothing/water to feel the left over energy of the spent shaft. At 2 bands it still has very little tug, at 3 bands and all the way to 5 bands the tug increased decently but can't take the gun of ur hand. Recoil is very decent even up to 5 bands.

Now the 6mm plywood test. At 2 bands the super sharp Hawaiian shaft can only make round damage on the 6mm plywood but the shaft bounced back. Riffe stated shooting range at 2 band is 2.29 meters, so I guess I was shooting too far at 3.8 meters. 3 bands stated at 3.35 meters and it was quite honest because the shaft did penetrate about 3cm into the plywood but the I need at least another 10 cm if I want that flopper to toggle free on the other side. I have been using 6mm plywood as a rough guess that it should equal the complete penetration of double gills on a +-20 kg giant trevaly. I don't know if that is accurate, but at least I have a known reference to measure my set up. At 4 bands, the shaft penetrated the plywood only to be stopped by the flopper. At 5 bands, I was getting only extra 1 cm of penetration, still the flopper could not pass thru entirely. My conclusion for the time being is that, this short and light weight 7mm shaft does not have enough momentum even at 5 bands, I was not getting any extra significant benefit by the extra 1 band. Could it be that the shaft have reached its theoretical maximum speed limit as I have predicted before between 4-5 bands? With no chronograph I can only to speculate. The extra resistance of the bulging flopper on the plywood grain only confuse the matter further. I have done test where angle of penetration matters for plywood. Also the low quality plywood is not similiar in hardness on its entire surface. Cheaper solution was a "ballistic putty" that I heard people use to simulate flesh penetration of projetiles.

5/16" / 8mm x 32 " shaft TEST with Large Spearhead.
This is the first time I ever use a large spearhead from Riffe. All my guns been Ice Pick or Hawaiian. Somehow I do not like Riffe spearhead cause it doesn't look sharp. I started with 3 bands and all the way to 5, shooting at water/nothing. The left over energy pulling the gun at 3,4 and 5 band was a prospect to lengthen the shooting line more. Recoil still in my limit even at 5 bands, like shooting my 124cm #2 Riffe at 3 bands with 5/16 shaft. Penetration test of 3 bands was not impressive. The massive size of the large spearhead frontal area was restricting penetration, only like 1.5 cm entered the plywood. At 4 bands the spearhead entered and again was halted by the flopper. At 5 bands the spearhead penetration goes almost to the end of the flopper but not enough to toggle out. Conclusion, this seems like a better overall deal than 9/32 shaft. If I use a Hawaiian at 5/16", penetration must be better for sure. Maybe next time.

3/8" / 8mm x 36" shaft TEST with large spearhead.
This is a wrong size shaft for the gun, should be 32" long. Anyway test was most impressive with this shaft. Shooting at water/nothing with 3 bands the gun get heavy tug from the spent shaft. Recoil is decent. At 4 bands recoil is still decent but stronger. The left over shaft energy was massive. At 5 bands and after my muscles were exhausted with at least a hundred band loading, I got so tired, the gun came out of my hand when I shot at nothing, it wanted to go rearward but the shaft left over energy was pulling it forward, saved my lip. Testing penetration in plywood was fun. At 3 band, the entire large spearhed exit out on the other side. At 4 bands the entire 36" shaft went thru completely. Bear in mind that this short 3/8 shaft has 1 extra custom loading tab, which the total becomes 3. At 5 bands it went thru and travel some more to hit a rock behind the plywood. The 3.8 meter shooting line was too short. I got out of the water and extend the line with 300 lbs mono, it get to be 5 wraps or 6 meter. I tried 5 band shooting from about 5 meter and the shaft penetrated 50% of its entire length into the plywood. Looks like 5 meter effective for a 20-30kg fish is not too optimistic. This extra length has no difference in accuracy, in fact it is more stable than the other 2 if at 4 and 5 bands.

Is this gun accurate ? Since I was doing penetration test and not aiming very much into the target, just the 60cm x 60 cm plywood and the 5 cm black dot target is too hard to see at 4 meters or more, I can say that I need to practice to shoot this gun at high power setting of 4 or 5 bands. By the time I had enough rest, I can shoot 1 hand at 5 bands.

My shooting has a tendency to shoot a bit left. I also find it difficult to shoot such a short gun, aiming is tough, especialy with short 32" and 34" shaft. The aiming make it difficult to shoot consistent in the low-high department. Left-right no problem.
If I were to test only at 3 meters, maybe a different story.

Since this is my first time with mid-handle in such thorough detail, I still prefer aiming with a rear handle. Also to note that at 5 bands, muzzle recoil is evident using 3/8 shaft if on a single hand shot, low shot tendency is quite obvious. 2 hand shot is a must for shooting at 5 meters away target.

Tracking, this short 81cm mid-handle track better than my 85 cm pneu, lovely even with floater wing kit. Overall, I am very happy. I also got to realize that since the gun is light in water and can change aim so fast, a good technique is required to shoot consistently accurate at 4 or 5 bands. Why ? A smaller gun swing easy, at the same time it is not stable as a long gun which is harder to swing. Being short, a slight movement on ur hand results in a big degree of shaft shift at impact at 5 meters, only natural.

Say shaft whip, recoil and all other accuracy destructing issue not playing any factor, holding this short gun properly is a must. I feel like I am shooting a pistol with this gun, more practice is needed.

What's the botttom line? Must conduct more test. 3/8" shaft at 36" is good for this gun even if it seems too long. This gun can replace my Riffe #2 for strong current and close quater work, I am very happy to use it as a 4 meter effcetive gun. Next test is to use Ice Pick on 3/8" shaft and a 5/16 Hawaian shaft at 34" or slightly more, say 36".

If this is to be made as a second shot mercy killing gun at 2-3 meters for very big game, it has the potential with 3/8 shaft.

I never knew that shaft mass/diameter even for a gun this short can change the ballistic quality so much IF 4 and 5 bands is available to be used. In fact if big power is available, a short 81 gun ballistic quality seems to get better improvement than my 124cm gun.
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Old 09-09-2003, 08:50 PM   #2
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Interesting tests. I have to read it several times though.
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Old 09-10-2003, 11:00 AM   #3
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Great info, Iya!
“If the natural tendencies of mankind are so bad that it is not safe to permit people to be free, how is it that the tendencies of these organizers are always good? Do not the legislators and their appointed agents also belong to the human race? Or do they believe that they themselves are made of a finer clay than the rest of mankind?”
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Old 09-24-2003, 10:18 AM   #4
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And the nobel prize goes to........
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Old 10-01-2003, 11:41 PM   #5
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I cut and pasted all of Iya's test posts from DB. I go back a read em once in a while; especially before I make modifications or look to buy a new gun. I don't need to tell you all that the guy is thorough .

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Old 10-08-2003, 03:09 PM   #6
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Iya, got tired of reading, sorry. I think you lost me with the centemeters... It's me, not you. It is fun testing stuff like that though. I shot my 450 JBL (home made bands) at a football field with a 5/16" shaft at a 45 degree angle and it went 92 yards... It broke at the notch when it landed.....

In a nutshell what I've found with using cable and a riding rig is that the 5/16ths shaft has better speed but not as much punch as a 3/8ths shaft. I like the heavier shaft because of my diving environment. With each shaft there is a trade off.
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Old 10-08-2003, 07:02 PM   #7
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How fast was the plywood swiming.
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