Home Tournaments Calendar Weather Merchandise Sponsors

Go Back   Spearboard.com - The World's Largest Spearfishing Diving Boating Social Media Forum > Spearfishing Gear > All About Guns

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

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-05-2018, 09:27 PM   #1
Straits
Registered User
 
Join Date: Jan 2018
Posts: 24
Aimrite King Venom 100cm setup questions

Hi all, long time lurker, recently joined the board, and just approved to post.

I've had an Aimrite KV-100 for 5 years now and love it. Unfortunately, not knowing much about gun set up and replacing perishable parts over the years, it's accuracy has declined and it's become unreliable and frustrating. After devouring the posts on this site I think I've got a better understanding of where I've gone wrong in the past and looking to correct it. Below are the issues I can find so far.

Shooting line. Comes stock with mono single wrap. I bought a huge roll of 2.2mm mono when it first needed replacing and have been using it since. Unfortunately this thickness has meant it is a little tight getting the spear into the mechanism and I suspect has contributed to the issues of accuracy. I've replaced with 1.8mm mono, and it is now clear of the sides when loading the spear.

Spear. Comes stock with a 7.5mm Rob Allen spear, 140cm length (though the mechanism safely takes a 7mm). I felt it was a little heavy in the nose, and changed to a 7mm spear, which hasn't changed the slightly heavy feeling nose. Accuracy has been worse since sadly. I'm going back to the 7.5mm spear. Would anyone suggest reducing length to 130cm to reduce the nose end weight? What would this do to accuracy? Would it alter the recommended band lengths?

Trigger. No changes. Well maintained. Love it. The safety feels natural in my hand and it's one of the reasons I got this gun.

Bands. Comes stock with 2 x 16mm rubbers. Band eye to notch is (A) 85cm and (B) 95cm, with band lengths come stock at (A) 55cm=309% stretch and (B) 60cm=317% stretch. I have previously gotten pre-made rubbers sent from Aimrite, though over the years the rubber feels older and less robust, and not knowing the source and age of them I am now keen to do my own. I've bought 14mm small ID rubber. I've read 340%-360% stretch to start is wise, and can cut shorter accordingly. As such I'm planning to use the following to get the desired length:
(A) (85x2)/3.5=48.5cm for a 350% stretch (knot to knot)
(B) (95x2)/3.5=54cm for a 350% stretch (knot to knot)
Any pitfalls or suggestions to the above plan?

I reef spear with this gun, mostly coral trout, tusk fish, jacks, an crayfish, and used to be able to shoot the eye out of most fish. I want to get this gun back to that accuracy and figure I'll get a better understanding of gun physics along the way. All and any help is appreciated.

Thanks
Straits
Straits is offline   Reply With Quote
Old 02-05-2018, 11:44 PM   #2
2fishin2
Pacific Spearo
 
Join Date: Jul 2007
Age: 57
Posts: 3,196
Re: Aimrite King Venom 100cm setup questions

Change to a 130cm 7mm shaft. It will take the "nose heaviness" away guaranteed. 2 14mm bands at 350%
2fishin2 is offline   Reply With Quote
Old 02-06-2018, 02:50 AM   #3
Straits
Registered User
 
Join Date: Jan 2018
Posts: 24
Re: Aimrite King Venom 100cm setup questions

Thanks for the reply 2fishin2,

How much does reducing the spear 'hang' affect accuracy and the band width/length equations?

Straits
Straits is offline   Reply With Quote
Old 02-06-2018, 07:06 AM   #4
Red Tide
Registered User
 
Red Tide's Avatar
 
Join Date: Jan 2004
Location: Tampa Bay
Posts: 1,263
Re: Aimrite King Venom 100cm setup questions

Quote:
Originally Posted by 2fishin2 View Post
Change to a 130cm 7mm shaft. It will take the "nose heaviness" away guaranteed. 2 14mm bands at 350%
Good advise
__________________
"It's not a problem... If you can fix it with money it's just an expense"
Red Tide is offline   Reply With Quote
Old 02-06-2018, 09:45 AM   #5
xrispearo
you cant see mee
 
xrispearo's Avatar
 
Join Date: Jan 2007
Location: SORIAPP
Posts: 2,307
Re: Aimrite King Venom 100cm setup questions

reduce shaft to maybe 120 or 130cm.
16mm bands
get a plastic bottle for testing in the ocean or lake
__________________
Man In His Element
xrispearo is offline   Reply With Quote
Old 02-07-2018, 04:24 AM   #6
Straits
Registered User
 
Join Date: Jan 2018
Posts: 24
Re: Aimrite King Venom 100cm setup questions

How much does changing shaft length and diameter affect the other variables?

A 7.5mm x 1400mm shaft has volume of 67,725 cubic mm (1400x(pi R squared)) where R is 3.75.
A 7.0mm x 1400mm shaft has volume of 53,851 cubic mm (R is 3.5) which is 20% less volume and therefore mass. Is this correct?

A 7.5mm x 1300mm shaft has volume of 57,403 cubic mm which is 15% less volume that the 1400mm same diameter.
A 7.0mm x 1300mm shaft has volume 50,004 cubic mm which is 25% less volume than the original 7.5 x 1400mm spear.

Please correct me if this maths is wrong (not my strong point). If correct then these are big mass changes. Would it still be recommended to use the same band width and stretch regardless of these changes?
I feel like there should be some adjustment made, just not sure where?
Straits is offline   Reply With Quote
Old 02-07-2018, 06:37 PM   #7
Marco
Registered User
 
Marco's Avatar
 
Join Date: Jan 2007
Location: Panama City, Panama
Age: 52
Posts: 2,343
Re: Aimrite King Venom 100cm setup questions

A shorter shaft would give you higher shots. Your brain will correct it overtime. Take some pool practice and you will master it.

I would cut the bands to 300-320% to start. Everybody talks about 380%, then you see them either missing shots or farting to load them...

You can always cut some more if needed.
__________________
Marco

A bad day fishing is ALWAYS better than a good day at work
Marco is offline   Reply With Quote
Old 02-07-2018, 11:15 PM   #8
fr0sty
Registered User
 
Join Date: Aug 2013
Location: Cambridge, MA
Posts: 161
Re: Aimrite King Venom 100cm setup questions

farting to load...

for my guns, i've done the 14mm small id bands at 350% which is somewhat in the middle of recommendations. You could do 300 and then cut again, but it 350 is pretty common and a lot people have success with it. I'm also lazy and would rather not want to cut and tie them up again.
fr0sty is offline   Reply With Quote
Old 02-08-2018, 06:52 AM   #9
2fishin2
Pacific Spearo
 
Join Date: Jul 2007
Age: 57
Posts: 3,196
Re: Aimrite King Venom 100cm setup questions

Farting to load... That's a classic ha

I'm 30cm overhang is perfect for all pipe guns and wood guns also. Any less you struggle to get a good aiming point. 40cm is industry standard for rail guns. Problem with that length is nose weight in short guns like yours and in longer guns both weight and shift whip. Your perfect setup is a 30cm overhang with 14.5 or 14 mm bands cut at a starting length of 350%. After they stretch out you can cut down and use for a longer time. With a short gun like that, you won't be taking long shots so perfect performance and tuning won't be as critical as shooting longer guns and larger fish
2fishin2 is offline   Reply With Quote
Old 02-08-2018, 09:36 AM   #10
tuffstuff
Mathew Goncalves
 
tuffstuff's Avatar
 
Join Date: Sep 2007
Age: 30
Posts: 1,746
Re: Aimrite King Venom 100cm setup questions

I know that I really liked going from a 180cm 7mm shaft to a 170cm 8mm shaft on my 140 railgun. That way the gun was more maneuverable; with a stiffer shaft that was less likely to bend and had about the same stopping power.
tuffstuff is offline   Reply With Quote
Old 02-09-2018, 08:01 PM   #11
Straits
Registered User
 
Join Date: Jan 2018
Posts: 24
Re: Aimrite King Venom 100cm setup questions

Thanks for all the replies.
130cm shaft is in the mail and on it's way.

I've tied the bands at 350% as calculated above. First time I've ever tied bands. Used spectra loop at each end, with a solid double granny/overhand knot. Fiddly to get into the small ID hole, but silicone spray helped and needle nose pliers did the job. Double constrictor knot next, which was easier than I thought it would be. Then used dyneema for the wishbone section, and can lengthen or shorten a few centimetres for tuning.

No pool and dirty ocean water out the front from recent rains means I can't test it yet, but very keen to see how these changes go.

I'll try figure out uploading pics, though it's nothing special to look at compared to the gun porn on here.
Straits is offline   Reply With Quote
Old 02-25-2018, 04:35 AM   #12
Straits
Registered User
 
Join Date: Jan 2018
Posts: 24
Re: Aimrite King Venom 100cm setup questions

Tested the gun today with acceptable visibility.
Feels a lot lighter in the hand, and the nose heaviness is gone.

Bands were much easier to load. Though never a real issue before, I do tend to shoot the gun rather than unload to avoid the pull required to release tension when getting back in the boat, and I can see myself easily unloading each move which does save time.

Shot were far more accurate. Baitfish through the eye first, then a tropical crayfish side shot as he crawled out of his hole, then a coral trout just behind the eye stoning him. I need to get it out more, but this early test was very promising and I'm pumped it's actually working.

Thanks to those who provided advice.
I'll get cracking on the 115cm KV Aimrite Roller that has been giving me similar issues...
Straits is offline   Reply With Quote
Old 02-27-2018, 09:18 PM   #13
getawayFK
Spearo-doc
 
getawayFK's Avatar
 
Join Date: Jul 2007
Location: Gainesville, FL
Age: 33
Posts: 203
Re: Aimrite King Venom 100cm setup questions

2x 14mm Small id bands stretched at 350-370%, w a 7.5mm shaft 25-30 overhang (or best, 15mm Small id x2, 380% stretch, 8mm shaft. The KV has enough mass to absorb the recoil but 380% stretch w these small id band is a work out !


Sent from my iPhone using Tapatalk
__________________
" The sea, once it casts its spell, holds one in its net of wonders forever" --- Jacques Yves Cousteau
getawayFK is offline   Reply With Quote
Old 08-17-2018, 08:59 PM   #14
Straits
Registered User
 
Join Date: Jan 2018
Posts: 24
Re: Aimrite King Venom 100cm setup questions

Old post I know, but wanted to feedback for anyone reading in the future.

7mm shaft, 130cm length, on the 100cm King Venom Aimrite, is a good spear. Very slight nose heaviness but I'm being picky here.
14mm small ID bands x2 stretched to 350%. Easy to load, shoots smooth, accurate, minimal/negligible recoil.

I've had the opportunity to take down a lot of reef fish with this gun since the last post. It's like a new beast again.

Thanks again to all who provided advice.
Straits is offline   Reply With Quote
Old 08-18-2018, 01:19 AM   #15
doyenofcastle
Registered User
 
Join Date: Mar 2015
Posts: 284
Re: Aimrite King Venom 100cm setup questions

Quote:
Originally Posted by Straits View Post
Old post I know, but wanted to feedback for anyone reading in the future.

7mm shaft, 130cm length, on the 100cm King Venom Aimrite, is a good spear. Very slight nose heaviness but I'm being picky here.
14mm small ID bands x2 stretched to 350%. Easy to load, shoots smooth, accurate, minimal/negligible recoil.

I've had the opportunity to take down a lot of reef fish with this gun since the last post. It's like a new beast again.

Thanks again to all who provided advice.
shaft overhang ?
doyenofcastle is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:00 PM.


The World's Largest Spearfishing Diving Social Media Forum Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright ©2002 - 2014 Spearboard.com