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9/16" Brass Over 17/32" Brass...why?

About to mod...Need help...

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#1 XxCoMmAnDoxX

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Posted 11 July 2004 - 03:26 PM

I understand if you are using it is a coupler... (Load dart into 17/32", put 9/16" over...), but in THISmodification, I don't see the point? Can someone please explain it to me?
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#2 1313

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Posted 11 July 2004 - 03:55 PM

because the inch or so of 17/32 brass is tighter than the 9/16 so it will make the plunger make more pressure before it will shoot the dart, the 4 inches of the 9/16 brass will just hold the dart longer until it leaves the barrel with less constriction than if the whole barrel was 17/32. If that makes sense :D
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#3 XxCoMmAnDoxX

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Posted 11 July 2004 - 04:01 PM

Well, using that logic, why not put the 17/32" into a progressingly series of SMALLER Brass to make the pressure even greater?

Also, I never understood why you use 9/16" as the barrel in the first place. Why not use 1/2" Brass. It is a tighter fit, doesn't that equate to a greater range?
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#4 xedice

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Posted 11 July 2004 - 04:14 PM

If your whole barrel is tight, you lose a lot of range. If only a small amount of 17/32 is used, it allows the pressure build up to occur, the 9/16 for the majority of the barrel is fairly loose fitting on the dart so that the dart can slide easily through it and gain accuracy from the barrel correcting it.
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#5 XxCoMmAnDoxX

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Posted 11 July 2004 - 04:20 PM

the 9/16 for the majority of the barrel is fairly loose fitting on the dart so that the dart can slide easily through it and gain accuracy from the barrel correcting it.

So...Does that mean 1/2" CPVC is not good because it's too tight? What about an AT2K with CPVC Breech loading? (Single Barrel). Would it be better to do the 17/32" Brass and 9/16" Brass as a "Brass Coupler"?

Also, you load the dart into the 17/32", then put the 9/16" Brass (Nested in 1/2" PVC) OVER the 17/32" Brass? Correct?
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#6 cxwq

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Posted 11 July 2004 - 05:12 PM

A few points:
  • FBR that's nominally 1/2" actually varies quite widely in size
  • The only reason I use 9/16" brass is because of my particular size of FBR
  • 9/16" (OD!) K&S brass is actually 17/32" ID
  • If your tubing ID and FBR OD are an exact match, there will be much friction.
  • On a spring gun, you want the dart to be held tightly enough for the plunger to build up some steam before the dart breaks free
  • There's such a thing as too much of the above - the plunger won't be able to get the dart out
  • 1/2" CPVC is less than 1/2" ID
  • 1/2" PVC is more than 1/2" ID
  • This article explains the ideas behind different barrel choices.

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#7 XxCoMmAnDoxX

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Posted 11 July 2004 - 05:46 PM

On a spring gun, you want the dart to be held tightly enough for the plunger to build up some steam before the dart breaks free


So 9/16" Brass is not good for a spring gun because it is too loose. It is, however, good to use 9/16" Brass in combination with 17/32" Brass. This is because when you load the dart into the 17/32" Brass, it WILL be tight enough to "build up steam". Is this correct?

But then you go onto say...

There's such a thing as too much of the above - the plunger won't be able to get the dart out


Does this mean 1/2" CPVC is always a poor choice? When (if at all) is it appropiate to use 1/2" CPVC?

This acticle explains the ideas behind different barrel choices.


I read the article and it did not have the info for CPVC I was looking for. Keep in mind I am talking about modding spring guns.
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#8 Ash

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Posted 11 July 2004 - 07:02 PM

Why don't you just go try it and find out for yourself?
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#9 cxwq

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Posted 11 July 2004 - 07:28 PM

Forget anything you've read about particular materials until you understand the following.

The only thing that matters is what fits your particular darts.

For pump guns, a perfect to slightly loose fit is ideal.

For spring guns, use the above combined with a constriction at the base of the barrel to hold the dart tightly at first, then let it build up speed smoothly.

For small volume spring pistols, a very short, slightly tight overall barrel will sometimes work quite well.


Brass is good for most people because it's adaptable for pretty much any FBR - you can buy it in 1/32" increments and it nests perfectly making constrictions easy. CPVC, PETG, copper, etc are more dependant on luck in finding a good fit with your darts. Some people have great success with them, some don't. It's entirely due to slight (sometimes significant) variations in the size of their FBR.
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#10 AirApache

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Posted 11 July 2004 - 07:30 PM

That helps him, :D . [EDIT] I wasn't referring to Cx..he posted before I finished. I was referring to Ash. Sorry Cx :( [/EDIT]

Okay, here I go.

9/16 brass works awesome with all guns, as long as you use fitting FBR. In most cases, your FBR will fit nicely.


It doesn't make sense to nest (that's what the telescoping of brass is called) brass in all spring guns, just because the gain won't be significant in some of them. The SSII mod that you saw is just a more complex version of the mod, and it's not necessary to nest it. But because the SSII is considered a powerful spring pistol, it could be worth doing that.

Nested brass is awesome because you "build up steam" to you use your words, and then when it pushes out of the 17/32 brass, it goes into the looser 9/16 and shoots out without much friction to resist it.

CPVC is very good, but you have to stretch your FBR to fit it nicely. You don't want to have to jam it down. Because the CPVC's ID is smaller, your stretched FBR will still fatten out after you've pushed it down. However, because you will have stretched it, it won't get stuck. Instead, you'll just have a powerful shot. CPVC is also very nice because it's EXTREMELY cheap.

CPVC can be used in pretty much all guns, though you need to remember to either get a smaller version of 1/2" FBR, or you need to stretch it out consistently. I'm not an expert on CPVC, mainly because I brass my guns. Though the type of barreling you use does affect the range of the gun, keep in mind the thing that makes it all work is that your FBR has to fit.

I hope this cleared some things up.

AA

Edited by AirApache, 14 July 2004 - 12:07 AM.

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#11 XxCoMmAnDoxX

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Posted 11 July 2004 - 09:15 PM

Yes, that cleared it all up. Thank you. I never knew 1/2" FBR can differ slightly, that makes all the difference. Also, I thought if you have a tighter fit, it is better, so I thought CPVC is the best choice. Now that I'm all clear, I'm going to modify the guns I haven't modded yet.
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#12 Ragornocks

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Posted 12 July 2004 - 08:11 PM

The only thing that matters is what fits your particular darts.

Damn, it's no different. I've had to tell about 3 kids this week the same thing about paintball.

Good luck with those guns, man.
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