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Inaccurate JBL Sawed Off - Switch down to 7.1mm shaft?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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ington6

Member
Aug 22, 2019
9
0
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Hi guys,

I have an old JBL Sawed Off which is about a 85-90. I live down in Costa Rica and we dont have great visibility very often on our shore dives with all that water moving. I've never had trouble hitting fish and have shot guns my whole life, but this JBL just seems super inaccurate. I'm 0/5 on my last shots.

It has 2 x 16mm bands (a tad shorter) and a 8mm shaft. The 8mm JBL's come with a threaded tip so you can add other tips on top. However, it is a pretty blunt and dull tip underneith and I dont run it with any additional tip on the threads. Compared to other tips it just doesnt look like it would penetrate well at all.

Also, looking around at other setups, it seems like this shaft is pretty thick for this gun. Most other guns of similar size are running 7.1mm or at most 7.5mm shafts. Should I try downsizing shaft diameter to help with the recoil? I'm mostly hunting shallow and around reefs.

One more theory... the gun is currently double wrapped. Should I switch to a single or 1.5 wrap with this setup? Im also thinking maybe some of the rigging on the double wrap could be throwing off the shaft on release.

Any help would be greatly appreciated.
 

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ington6

Member
Aug 22, 2019
9
0
11
36
OR, should I just move away from this old JBL all together and look for something else? Thanks for all the help !
 

popgun pete

Well-Known Member
Jul 30, 2008
4,107
1,096
353
I have two of those, one has the biplane wing muzzle and the other has the simple band slot muzzle. The 5/16" spear (8 mm) is standard on JBL guns. The alloy guns are rather light for what they shoot and even lighter when the alloy muzzles were swapped for plastic versions (cheaper to make as no anodizing or painting). Two hand shooting is the best way to control them, one hand clamped over the other or one on the cocking stock butt.

You can check if the spear is straight by rolling it on something dead flat or rotating it while looking along the shaft from one end. Make sure the floppers lie flat when folded back and they should have a sliding keeper ring that traps them in place.

Make sure the lineslide and its washer travel freely on the shaft as straight shooting relies on it not getting stuck. The line release is pretty foolproof on those guns, but the lever which is biased by a light spring needs to move freely once the trigger mechanism is discharged.
JBL Magnum mech 4.JPG
 

ington6

Member
Aug 22, 2019
9
0
11
36
Definitely no sliding keeper ring. Here is a pic.

So I probably should start messing around with shafts? I know it is probably made to shoot a 8mm but it just seems aggressive for this gun and the size fish im targeting. Was hoping to dial it in a little better but maybe I just need to work on my skills.
 

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popgun pete

Well-Known Member
Jul 30, 2008
4,107
1,096
353
Definitely no sliding keeper ring. Here is a pic.

So I probably should start messing around with shafts? I know it is probably made to shoot a 8mm but it just seems aggressive for this gun and the size fish im targeting. Was hoping to dial it in a little better but maybe I just need to work on my skills.
I was referring to the original spear which you seemed to be talking about, but I wondered why you had the attachment photo of an integral tip shaft. That shaft probably has no line slide and the JBL muzzle uses one and the washer behind it to centralize the shaft in the muzzle, without it the shaft will not be as well guided unless the gun has a true glide track on the barrel tube. Even then the shaft can flop around. Mix and match does not always work out when you change the gun’s original configuration.
 

hteas

Well-Known Member
Mar 9, 2005
961
137
148
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The poblem may be that you are pointing the gun, rather than aiming it. Try aiming along the barrel to get the vertical accuracy you need. And, as suggested by popgunpete, shoot with one hand on the handle and the other on the buttpad to stop recoil problems. Recoil can lift the front of the gun, making the shaft go lower. This sounds crazy, but as the front of the barrel lifts, it lifts the tail of the shaft above the tip, making it shoot low.
 
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