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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
IyaDiver
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The ballistics of 9/32" Vs 5/16" Vs 3/8" shafts

Gentlemen,

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
Marcus
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Great info, Iya!
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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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IyaDiver

How fast was the plywood swiming.
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