G3 accuracy problem (SOLVED)

[StuartL]

So I bought a secondhand G3 a few weeks ago and from the first skirmish the shots were all over the place. My (heavily tinkered) AUG was outperforming it by an order of magnitude, in fact anyone throwing sticks for a puppy was outperforming it.

It turns out the problems were a combination of several things, some of which are unique to the G3:

1) The front portion of the barrel attaches to the receiver with two screws. These screw hold the entire front half of the rifle onto a small piece of plastic which is moulded onto the receiver. This piece of plastic appears to be vastly underengineered. Gluing it with lots of epoxy (taking care not to glue anything into place that I wanted to remove) resolved a major amount of barrel wobble.

2) The flash hider and front portion of the outer barrel (you could consider this just a mount for the flash hider) are attached with a single grub screw under the front sight. Over tightening this grub screw has several consequences:

2a) The flash hider no longer lines up with the inner barrel, meaning BBs hit it on the way out.

2b) The inner barrel gets distorted.

2(cont)) Under tightening the same screw means that the flash hider is loose and wobbles around, meaning BBs hit it randomly on the way out. I believe this is what was happening to my shots.

3) The inner barrel is not a tightbore (on the Tokyo Marui rifle).

I have now rebuilt the inner barrel and flash hider assembly for the cost of a Madbull tightbore barrel, hop up rubber and the dog-bone style bucking. This came to about £35 before shipping.

To put the 509mm tightbore in I had a local engineering firm drill out the flash hider (and foremost piece of the outer barrel, the one that didn't line up) to 9mm and the 509mm barrel now comes to the first hole in the flash hider. The engineering firm did the drilling as a favour.

I then nudged the grub screw to a 'snug' fitting, fitted the hop-up assembly with the new rubbers and reassembled the rifle.

The upgrade took me about ten minutes plus the walk around the corner to the engineering firm.

Before, at 100ft, I couldn't reliably hit a man in ten shots.

Now, at 40ft, I put three BBs through the same hole in a piece of paper.

I'm looking forward to Sunday :D

[Chandler]

Re: G3 accuracy problem (SOLVED)

glad to hear you have it all sorted! My SA80 is being a right pain accuracy wise! at 40ft i couldent hit a stop sign lol no idea what it is!

Chandler

[StuartL]

Re: G3 accuracy problem (SOLVED)

My AUG also had the inner barrel loose in the outer barrel. I put some insulating tape on it to make it a snug fit and that's now similarly accurate.

One thing that's worth doing is backing the hopup all the way off. With the hopup off you can then see if it's shooting consistently, even if you're not getting decent range. If it's consistent with the hop-up off but wild with it on then it's a hop-up or bouncing-BB problem (where the BBs, pushed downwards by the hop-up, bounce down the barrel).

[Chandler]

Re: G3 accuracy problem (SOLVED)

aha! very clever indeed! i shall check this out saturday and then report back thanks mate
Just had a look the inner barrel seems to press against one side of the outer barrel.. could this be why my bb's seem to curve?

Chandler

[StuartL]

Re: G3 accuracy problem (SOLVED)

aha! very clever indeed! i shall check this out saturday and then report back thanks mate
Just had a look the inner barrel seems to press against one side of the outer barrel.. could this be why my bb's seem to curve?

Chandler

Probably finding the problem and centralising the inner barrel will also find out why they're curving to the side. I'd strip the hop-up out, realign the inner barrel to the hop-up and make sure it's central in the outer barrel with some insulating tape.

That'll probably make some difference.

[Chandler]

Re: G3 accuracy problem (SOLVED)

hey mate... an update on that really... put tape at about 5 places down the barrel and its dead centre all the way down now but shooting down my garden on full auto resting on the wall will send bb's left an inch then right an inch.. so at about 6-7 meters my groupings are about 3inches wide.. is that right?

Chandler

[Caveira]

Re: G3 accuracy problem (SOLVED)

Could be the wind, but more probably it's the shape of your hop nub. If it's flat, or curved into the barrel, then the BB can move left or right of the nub. Ideally you want one that's an inverted v shape, or curved up from the barrel, as these give a consistent result.

The element H nubs are fantastic.

/\
O = good

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O = bad

[Ells]

Re: G3 accuracy problem (SOLVED)

big out H hops are meant to be pretty good aswell, although £5 ea :|

[StuartL]

Re: G3 accuracy problem (SOLVED)

I used the Madbull H nubs that came with the hopup rubber.

[Chandler]

Re: G3 accuracy problem (SOLVED)

right. well i brought madbull hopup rubbers ( i got two in a packet ) so i fitted them but the rubber seemed to be much thicker than the one i took off.. and with the nub which was also bigger.. even with the hop fully off it was still so far into the barrel it would say my bb's off miles high! so i'm using the old nub which is smaller.. neither of those was H shape though!

Chandler