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Discussion Starter · #1 ·
While I love EdGI, they did end up shipping a barrel to me ported as follows:

Now, my VSR does still considerably outperform the world's best Tanaka (his name is Ashvik btw), but I'm too paranoid that those ports are effecting consistency as BBs run over(?) them; it seems impossible given the accuracy/precision I'm seeing, but I can also visibly see BB skid marks on the top of the barrel that are spooky close to the ports (oh yeah if you were still wondering, BBs ride the top of the barrel- at least by the end of mine they do...at least the ones that leave SKID MARKS do...(no clue, don't ask, I've fired like 15 types of BB through it)).

So. Anyone familiar with what I need to ensure the barrel bore/crown can be refinished sufficiently from home?
Will be Google-ing away, but obviously figured I'd ask if anyone has experience here.
I have what I need to cut the barrel [and add my own slit ports to the low sides maybe?], but I'm not confident about the finer issue of barrel bore/crown.

Might also just see if EdGI wants to go 101% and take responsibility on fixing it, but if I can, I'd rather avoid that for everyone's sake.

:shot:
 

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Take a cone shape grinding stone on your Dremel to remove material you don't want. Then put a round head Philips screw on your drill, add polish compound on it and just push it against the nozzle. Keep drilling until it's smooth and shiny.
I have marks all over my barrel if I don't clean it long enough, so I'm inclined at bbs don't ride the top of the barrel.
 

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You bet, Mr. Marker...you can do crowns at home. wyz2285 is on the track using the cone shaped dremel stone. It self centers into the bore and as long as you keep the tool in line with the barrel, it'll give you a pretty nice cut. The phillips screw thing is new! hehehehe. Usually I'll just go to the rubber abrasive conical bit and run that until smooth, then finish with a bore felt with compound. Comes out like glass...

If you're super picky about angle you can also use a drill press to cut the crown...if the press allows the length of the barrel.
 

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Discussion Starter · #5 ·
I have marks all over my barrel if I don't clean it long enough, so I'm inclined at bbs don't ride the top of the barrel.
Hm, very interesting actually. What's the volume ratio like, and what BB weight do you think is doing it? It's clear as day looking at my barrel that the bottom is spotless and the top is getting traffic.

Usually I'll just go to the rubber abrasive conical bit and run that until smooth, then finish with a bore felt with compound
Would you be able to link me the specifics for the polishing steps after grinding?
 

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Link the specifics? Ummm, nope. No can do. I wish I could, but it’s years of machine experience that I draw from. Hahahaha. No recipe, I just know how to work metal. But, hey, doesn’t mean I can’t try and help...what exactly is the question? :)


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Ported cylinder, 300mm 6,08 steel barrel, 0,25g bbs. I didn't clean it for 2 years just to observe the marks. After all the use , the marks are not concentrated enough on any direction to form a majority so my conclusion was the bbs bounce around (the Reynolds number confirms laminar flow can't happen, I don't believe in the air cushion theory with turbulence flow personally) therefor I stick to custom polished steel tight bores, bore quality and consistency together with bb quality and consistency is what matters IMO.
 

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You could get knife stropping compound of various grits for polishing once the more abrasive dremel work is done. Few minutes with each compound should be plenty depending on what grit you stopped with for the major metal removal work.

Then finish with a diamond paste if you really wanna get fancy, but it's likely unnecessary.
 

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In that case I'd get an extra thick upper portion, but as I said, it's homogeneous. When I first found the marks (a few white lines here and there), I decided not to clean it and keep using it and observing it from time to time. The top portion never showed a clear extra mark than the rest.
 

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Discussion Starter · #11 · (Edited)
Link the specifics? Ummm, nope. No can do. I wish I could, but it's years of machine experience that I draw from. Hahahaha. No recipe, I just know how to work metal. But, hey, doesn't mean I can't try and help...what exactly is the question? :)
I understand, I actually just mean the 'rubber abrasive bit' you mentioned. I have some rubbery bits that came with the Dremel and I'm wondering if they're the same.
Primarily, I would just like to know I'm at least buying the correct final polishing bit, if you know what I'm looking for!

Ported cylinder, 300mm 6,08 steel barrel, 0,25g bbs. I didn't clean it for 2 years just to observe the marks. After all the use , the marks are not concentrated enough on any direction to form a majority so my conclusion was the bbs bounce around (the Reynolds number confirms laminar flow can't happen, I don't believe in the air cushion theory with turbulence flow personally) therefor I stick to custom polished steel tight bores, bore quality and consistency together with bb quality and consistency is what matters IMO.
What if you got skidmarks on the top of the barrel? But you didn't observe it in time. It got so dirty that it moved bb from the top and with time it just left marks all over?
Just sayin'
In that case I'd get an extra thick upper portion, but as I said, it's homogeneous. When I first found the marks (a few white lines here and there), I decided not to clean it and keep using it and observing it from time to time. The top portion never showed a clear extra mark than the rest.
Seems it would be possible the build-up never actually visually appears thicker in any section because of how tight the barrel is in general- maximum build up between 5.92mm and 6.08mm is .16mm, and if it was truly built up to maximum, the actual result after settling would probably be streaks at all angles.
In any case, I believe you that you're seeing different results - it's clear if you saw streaks anywhere other than the top at all, at any time - that's why I asked about your rifle's specifics. There's no doubt that in my build, BBs are riding the top, so my guess is it's related to volume and/or pressure- probably volume if springs tend to reach a higher pressure spike than HPA builds. What power are you putting out? I think I'm around 3 joules at 180PSI and .4something BBs- would have to check notes at home.
 

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Oh sure! No worries... yeah. It's the blue rubbery one that comes with a Dremel. You can finish the crown with that thing and have no issues. Shape is up to you. I've experimented with flared crowns, compound angles, different depths of cut, etc. They all work! hee hee hee. As long as the air can evenly dissipate out the end you're good to go. You don't have to be mirror finished or anything like that. :)

My BB's ride the top of the barrel as well. Interesting. There might also be a lift factor there depending how much backspin was imparted on the BB on the way out. Hmmm
 

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Simple. Tooling. Specialized tools like the ones needed to do that are expensive. Thus the barrels will be more as well to cover the costs for the tools and materials then add profit margin for the manufacturer plus markup for retailers.

When I looked into that a while back, I concluded that no one would buy a $250 super gimmicky inner barrel, except for a very small number of people.

There are other ways to achieve the same end result, but again custom made tools.
 

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So you all agree that the bb rides on top of the barrel.
While I don't think a cut to re center the bb is necessary (the top of the barrel is concave so the bb should be centered, in a tight bore it doesn't really have much space to wiggle), then wide bore air cushion theory is bullshit.
The active contact with the top of the barrel also means the bb definitely bumps on ported barrels.
Also at which point does the bb stop climbing to the top? Say you have a short inner and a longer outer, the bb would climb to the top of the outer too? But the bb leaves the barrel straight forward (hopefully, if we plan to hit someone)
I think I'll put a cheap brass tight bore on my dsg, dip in marker ink, dump a couple hicap then cut it open.
 

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A cheap "6,03 tight bore" runs a couple bucks around here, cheaper than the endoscope since the bore size shouldn't matter for the results. In fact I should use a bore as wide as possible (thinking of use 6mm ID extruded aluminium tubes, usually 6,1mm plus) so there are less chance for the bb to touch the entire inner surface.
 

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I would recommend zooming the camera to the end of the barrel so we could actually see what the problem is.

Lähetetty minun ONEPLUS A6013 laitteesta Tapatalkilla
 

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Discussion Starter · #19 · (Edited)
So you all agree that the bb rides on top of the barrel.
While I don't think a cut to re center the bb is necessary (the top of the barrel is concave so the bb should be centered, in a tight bore it doesn't really have much space to wiggle)
[...]
The active contact with the top of the barrel also means the bb definitely bumps on ported barrels.
[...]
Also at which point does the bb stop climbing to the top? Say you have a short inner and a longer outer, the bb would climb to the top of the outer too? But the bb leaves the barrel straight forward (hopefully, if we plan to hit someone)
1. The Devil's advocate would be that a concave brace would more easily allow wobble left and right whereas a notch would create a rigid center for the BB to ride in- but I'm not sure if that's a significant enough concept to consider...

2. Ehhh...I think this is a really enigmatic discussion. Theoretically, you could argue that if - looking down the muzzle - the barrel has >0 degrees of material to the left of perfect top center, the BB would have material to ride and not hit port hole ridges - as implied by your point above about the BB not needing a top notch - but...yeah I don't want to assume that, and personally doubt that's true, which is why, with my new discovery below [in response to Aapo], I am definitely re-muzzling my barrel :p

3. Personally, I think we can safely say the rise becomes moot (or even disappears entirely) beyond the scope of "inner barrel". Not only is the rise distance we know exists inside an inner barrel absurdly small (tiny fractions of a mm from middle to top- not going to be of much concern for outer barrels), but we all know after tuning our hop up that the trajectory of the BB is flat.
This does lead to an interesting question: Why does the BB rise to the top of the inner barrel? Flowing gas has a lower pressure than static gas, which should basically "suck" objects in (read: air flowing under the BB should cause the BB to move down). Again, I believe this is due to volume ratios and pressure- I think a high enough volume/pressure (in a general sense) behind the BB, along with the BB's backspin, would result in a consistent escape of air under the BB:
- Consistent: In this scenario, the escaping air is not lower pressure than surrounding air, but higher- it's pressurized air escaping the higher pressure zone to lower pressure in front of the BB
- Under the BB: The air will escape the easiest direction it can; here, that should be the opposite of the top- the hardest place, as the BB is inclined to move upward due to the hop up / Magnus Effect.
This would also serve to explain why a high source/barrel ratio would result in better accuracy [to a point]. This basically ends up being this conversation...
https://www.airsoftsniperforum.com/...lume-ratios-based-bb-weight-implications.html

I would recommend zooming the camera to the end of the barrel so we could actually see what the problem is.
Actually when I posted, no streaks seemed to actually overlap the ports, however after today's game, some certainly do...odd, I can't imagine what would have changed. I fired so many different BBs down that barrel, only top streaks, now one barrel cleaning and one game day later, and the streaks now show across the top 30%. The more I think about it the more interesting this is. I believe I was tuned ~10 PSI lower than before... ???
Anyway pictures don't really come out.

So now...how to decide how to port- if at all?? :nuts: >:D
Top notch for the BB to ride? But then how will that effect the route air takes around the BB? To counter/even that out, should I make a mirror bottom notch? Can I do that perfectly with a Dremel?? Will this potentially result in squeezing the barrel together causing jams at the muzzle??
Side notches to vent air symmetrically without interfering with the BB's contact on the barrel? Will this effect the route air takes around the BB? Does this mean I should do all four slits??
No ports at all? THAT'S NO FUN :lmao:
 
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