(Major) peformance decrease with tightbore barrel

[williamhorton]

I know this is a common problem, and I feel sure that I read about something very similar to this quite recently, but I've been through pages of threads and can't find it.

 

Anyway, my problem is thus: Today I fitted my TM G3S G-1 with a Prometheus 6.03mm precision barrel and Prometheus buckings and nub. The worst part was realising that the barrel and hop up unit just slid out with the receiver removed, and that I didn't have to take everything apart, but that's another story.

 

With everything back together, I went outside to test it, but it fired very weakly and inaccurately (which I assumed was normal, having fitted new parts) so I put a few mags through it, as one does, and still found the same problem.

 

Another cause for concern was that it was not feeding properly (I assume), it would not fire, then would fire two or three weakly (I presume they got stuck in the barrel and were forced out at once). It isn't the magazine, as I have tried three separate ones, which were working before. I also thought it might be the BBs in the tightbore (Q Bullets, which I had heard worked well), and replaced them with 0.25g KSC Perfects, which should not jam, but found the same problem (the BBs slid down the barrel without jamming when I rolled them down).

 

I haven't had a chance to switch back to the original barrel, but I believe the problem may have something to do with the bucking being "contaminated", as it managed to find its way into some silicon grease.... However, as I said, I had put many BBs through it to no avail.

 

Unfortunately, I cannot try the original bucking, as it... destroyed itself when I removed it (my fault), which isn't helpful. Any ideas? I would like to use the new barrel and packing, having spent a lot of money on them. If you could help me, or point me in the direction of a thread which covers my problem, then I would appreciate that greatly. Sorry for the long post, and thank you in advance.

[Con1Carry1911]

Some materials swell when in contact with silicone. The "nub" could be a bit too long also. Did you compare all new parts to the old before assembly? Sometimes on the G's you can put the hoput unit pin in backwards, and it will misalign the hop up/nozzle just enough to cause feeding/firing problems. Also, make sure your using high quality BB's with that new barrel. 6.03 id ID makes it important to get BB's with consistent OD and roundness specs.

[Glenn]

Feeding issues makes me suspect the hop up. Assuming you have everything assembled correctly, try using different combinations of your old and new components, to isolate the problem. If both barrels work fine with the old hop, then the new hop needs to be looked at.

[williamhorton]

Just to update, I have taken the bucking and nub out and cleaned the grease off them. I tried both the old barrel and the new barrel and it seems to have fixed the misfeeding. I think I have the pin the right way around, I have tried it both ways. I believe the original was going from left to right protruding out the left. One strange thing was that after I switched the pin (the wrong way round I think) it fired one shot the full distance and I was impressed. All the other shots have been very inconsistent. It might dribble out the barrel one shot, then go 15m the next. It rarely goes at standard velocity or range. Sometimes the hop up works and sometimes it doesn't.

 

I haven't got round to switching the nub to the standard; I'll do that later. I haven't been able to try the old bucking, as it is shredded. I can try the one from my brother's TM AUG, as I think they are the same. If the worst comes to the worst, I can always replace the whole hop up chamber, or just the bucking. I don't see why the new one doesn't work though.

 

Also, I am using KSC perfects, which I am told are very good quality BBs. I also have a new Prometheus nozzle which I am yet to fit, would this do anything to help?

[williamhorton]

Ok, so I put the old nub in and it was the same. So I thought that I would try the old bucking, which has a massive rip and a chunk missing out of the end, and it fires fine. That was pleasing, but now I have a supposedly good Prometheus bucking which doesn't work. I assume that it was damaged by the grease.

 

My question is: Is there any way I can recover it? I would like to use it. Many thanks to everyone who has helped me.

[Sale]

It's quite obvious that the Prometheus hop up sleeve (the part that goes around the barrel) is too tight for the BBs to enter. Hop up sleeves are cheap parts. Get another brand and try until you find one that works for you. Then stick to it and sell the others off. An opposite problem of your situation is when the hop up sleeve doesn't provide enough resistance for the BBs, resulting in double feeds.

 

There's no reason to stick to one brand (even a known one) if it just doesn't work for you. No matter how well Prometheus works for other people (I've had good results with them too), it's not helping you is it?

 

Before going into this, you might want to try this: Make sure the barrel is shoved into the hop up sleeve deep enough. You want the edge of the hop up sleeve to be flush with the opening where the plastic C-shaped barrel retainer goes. Otherwise the narrow end of the sleeve might be squeezed between the barrel and hop chamber in the wrong way, causing problems for the BB to enter.

 

-Sale