5 replies to this topic

[Foam of Grianter]

So I got some questions about adjustments to the Longshot Angel Breech. I don't own a Longshot or any brass pipes.
I read somewhere online before that 17/32" brass was the best size for doing barrel replacements. In the original Angel Breech, 9/16" brass was used for the barrel, which is a tad bit looser than 17/32". If I were to use Modified Nerf streamlines (OD of 0.5") wouldn't 17/32" brass barrels (ID of 0.503")get better performance than 9/16" brass barrels (IO of 0.535")? Has anyone ever tried using 17/32" brass for the barrel and 9/16" brass for the bolt? I thought about it a bit and 17/32" does have a bit more friction while 9/16" allows more air to leak, Another idea could be to nest some 17/32" inside the bolt receiver end of the 9/16". The initial friction from the 17/32" will allow the air pressure to build up more. Although, this idea is like creating tightening rigs or 9/16" but 17/32" is smoother than t-rings.
On the bolt of the breech, I was thinking of replacing the 1/2" brass with 1/2" aluminum. The aluminum has an ID of 0.4375", the brass has a ID of 0.472". I was guessing that the tighter ID of aluminum would increase air pressure thus improving range (and slightly softening plunger impact). I've actually tried the straw inside the bolt idea on my recon. I used thin straw (ID is 5mm), hot glue and silicone but I remember ranges actually decreased a bit. But maybe ranges reduced cause I did something. I remember my O-ring sucked at the time and I was very messy with the hot glue.
Another question I have is,has anyone tried the Angel breech variants on the other CS blasters? Was it effective. I've done calculations with plunger volumes and bolt lengths to find maximum barrel lengths. When using 9/16" for the barrel and 1/2" brass fr the dart pusher the maximum barrel length for inverse-plungers is 2.5" and 6.3" for the stampede. When using 17/32" brass for the barrel and 1/2" aluminum for the dart pusher the maximum barrel length for inverse plungers is 3.7" and 7.7" for the stampede. I didn't even factor in possible air leakage. I also didn't factor in if the forces from air pressures/air flow was greater that the forces from friction/air resistance in the barrels. So actual maximum barrel lengths are shorter. And you'd probably have to create some bolt locker mod on the stampede to make sure the dart exits the barrel before the breech opens.

[Daniel Beaver]

I won't comment on the angle breech stuff, because I'm not an expert on that. As for the straw mod and barrel length stuff...

Quote

I used thin straw (ID is 5mm), hot glue and silicone but I remember ranges actually decreased a bit. But maybe ranges reduced cause I did something. I remember my O-ring sucked at the time and I was very messy with the hot glue.

Two things are happening here. First, you're reducing dead space, which helps ranges (as it allows for a higher peak pressure). But the second thing that's happening is that you are obstructing the airflow between the dart and the plunger tube, introducing frictional losses (and other effects). In your case, the cross-sectional area of the straw is 85% smaller than the normal diameter, and so the negative frictional effects overwhelm the positive deadspace-reducing effects, resulting in a net loss in ranges.

Also, you might have just fucked up your seal or something.

Quote

I've done calculations with plunger volumes and bolt lengths to find maximum barrel lengths. When using 9/16" for the barrel and 1/2" brass fr the dart pusher the maximum barrel length for inverse-plungers is 2.5" and 6.3" for the stampede. When using 17/32" brass for the barrel and 1/2" aluminum for the dart pusher the maximum barrel length for inverse plungers is 3.7" and 7.7" for the stampede.

It's not that simple. Check out Doom's posts in this thread. You're much better of figuring out ideal barrel length through trial and error.




One last recommendation: put spaces between your paragraphs. The white space helps readability.

Edited by Daniel Beaver, 14 November 2011 - 06:41 PM.

[nerfnut23]

'Foam of Grianter', on 14 Nov 2011 - 10:11 PM, said:

So I got some questions about adjustments to the Longshot Angel Breech. I don't own a Longshot or any brass pipes.
I read somewhere online before that 17/32" brass was the best size for doing barrel replacements. In the original Angel Breech, 9/16" brass was used for the barrel, which is a tad bit looser than 17/32". If I were to use Modified Nerf streamlines (OD of 0.5") wouldn't 17/32" brass barrels (ID of 0.503")get better performance than 9/16" brass barrels (IO of 0.535")? Has anyone ever tried using 17/32" brass for the barrel and 9/16" brass for the bolt? I thought about it a bit and 17/32" does have a bit more friction while 9/16" allows more air to leak, Another idea could be to nest some 17/32" inside the bolt receiver end of the 9/16". The initial friction from the 17/32" will allow the air pressure to build up more. Although, this idea is like creating tightening rigs or 9/16" but 17/32" is smoother than t-rings.
On the bolt of the breech, I was thinking of replacing the 1/2" brass with 1/2" aluminum. The aluminum has an ID of 0.4375", the brass has a ID of 0.472". I was guessing that the tighter ID of aluminum would increase air pressure thus improving range (and slightly softening plunger impact). I've actually tried the straw inside the bolt idea on my recon. I used thin straw (ID is 5mm), hot glue and silicone but I remember ranges actually decreased a bit. But maybe ranges reduced cause I did something. I remember my O-ring sucked at the time and I was very messy with the hot glue.
Another question I have is,has anyone tried the Angel breech variants on the other CS blasters? Was it effective. I've done calculations with plunger volumes and bolt lengths to find maximum barrel lengths. When using 9/16" for the barrel and 1/2" brass fr the dart pusher the maximum barrel length for inverse-plungers is 2.5" and 6.3" for the stampede. When using 17/32" brass for the barrel and 1/2" aluminum for the dart pusher the maximum barrel length for inverse plungers is 3.7" and 7.7" for the stampede. I didn't even factor in possible air leakage. I also didn't factor in if the forces from air pressures/air flow was greater that the forces from friction/air resistance in the barrels. So actual maximum barrel lengths are shorter. And you'd probably have to create some bolt locker mod on the stampede to make sure the dart exits the barrel before the breech opens.

Not to backseat mod, Foam of Grianter, but try to repair your grammar before you get banned... It's not atrocious, but with all the new members we're getting in, be careful.

And to answer your questions, the barrel material can be tailored to your gun rather easily- going down 1 size of brass for everything CAN work if done correctly (meaning 17/32 rather than 9x16, and the like).

The aluminum idea is valid, but the problem is that there's a huge misconception here with smaller air opening = higher pressure = higher dart velocity. the reality of it is, to an extent, that's true. But, the problem comes in when you get tighter than the 'sweet spot'. The pressure that increases velocity is the pressure inside the barrel behind the dart, rather than the pressure in the plunger tube, so a tighter barrel with a clearer airflow to the dart, in theory, would work better. (in theory because I always use CPVC on an AT2K so I don't know for a fact about that.)

Good (aka non-sticky-as-Hell) foam is VERY important, because of the simple fact that if the foam is sticky, it'll take more work to get moving (potentially good) but it also takes more pressure to maintain its velocity down the barrel.

On the Stampede, the whole principle of the bolt-lock is actually the fact that the giant 'barrel' on the front of the gun is merely a hollow tube that has no effect on the dart's performance- or even hinders it. There is NO REASON to believe that a longer barrel that provides no seal works better unless there's an absurd amount of airflow (example: 1/2" Sched. 40 PVC with nanos linked to a Titan tank)- if you DID put an angel-breech on a Stampede, the best barrel length wouldn't be more than 6".

[SgNerf]

I've done brass breeches on various blasters, so perhaps i could share my experience on it...

'Foam of Grianter', on 14 Nov 2011 - 10:11 PM, said:

Has anyone ever tried using 17/32" brass for the barrel and 9/16" brass for the bolt?

Yes, 17/32" brass can be used for barrels, it just depends on your foam dart fit.

Note that the advantage of using 9/16" brass barrels is that you can have the flexibility to use other foam darts or stefans that have slightly wider OD. If you use a 17/32" brass barrel, you'll end up limited to only being able to use the narrower OD foam darts.

'Foam of Grianter', on 14 Nov 2011 - 10:11 PM, said:

On the bolt of the breech, I was thinking of replacing the 1/2" brass with 1/2" aluminum. The aluminum has an ID of 0.4375", the brass has a ID of 0.472". I was guessing that the tighter ID of aluminum would increase air pressure thus improving range (and slightly softening plunger impact). I've actually tried the straw inside the bolt idea on my recon. I used thin straw (ID is 5mm), hot glue and silicone but I remember ranges actually decreased a bit. But maybe ranges reduced cause I did something. I remember my O-ring sucked at the time and I was very messy with the hot glue.

The smaller ID of the aluminum can help reduce the deadspace in the bolt, the difference isn't much so it should not have any adverse effect (though improvements would also be minimal).

The reason why the straw method in your Recon mod didn't work is because the straw ID was too small and that ends up creating a restriction in the air flow, thus becoming a sort of air restrictor (btw, its the same as how an air flow speed controller works, it just narrows the openings in a valve).

'Foam of Grianter', on 14 Nov 2011 - 10:11 PM, said:

Another question I have is,has anyone tried the Angel breech variants on the other CS blasters? Was it effective.

I've done brass breeches on Nerf Recons and Longstrikes before but their performance improvements are minimal at best, that is because their reverse plunger volumes are too small (along with alot of deadspace inside the plunger too). The limited air volume doesn't provide enough force to propel the foam dart though longer 9-12" barrels (the foam darts usually get stuck halfway due to not enough power), so you'd have to use shorter 3-4" barrels. Small plunger volumes with short barrels results in rather minimal performance gains.

You can check out my Recon Brass Breech Mod Guide here: http://modworks.blog...-mod-guide.html

Imho... for the amount of effort to brass breech blasters, its more worth it to do them on blasters with larger plunger volumes instead.

Edited by SgNerf, 15 November 2011 - 02:13 AM.

[Exo]

The larger the initial volume of the gun, the better, because volume is the hardest aspect of the blaster to change.

One breech that's fairly popular on NerfRevolution is a 17/32" and petg breech. It provides the roughly the same results as a full prass breech, but it's a ton cheaper. Check it out here. I'm working on a version that can use CPVC and 1/2" brass, and the two materials mate and seal just as well with a little bit of work.

Clip guns are nice, but only one of them (longshot) has any real value to it, so you really have to consider the benefits of clips vs. using a wye or an rscb.

[Foam of Grianter]

Daniel Beaver: Oh I see, I guess the straw was too tight.

And thanks for the tip.

nerfnut23: I understand what you mean. You're probably right. Since air pressure goes in all directions it also slows down my plunger. That mean less air flow.

I was planning to Angel Breech the stampede. 6" sound good for a barrel. I was thinking of trying 10" to 2" barrels. I wanted to make 2 very minimized stampedes with short barrels, and 2 slightly minimized stampedes with 7" to 5" (depending what's most suitable) barrels.

And sorry for my bad English. I will try to fix that from here on out. Thanks for the heads up.

SgNerf: Oh okay I get it now. I will probably go with 9/16" brass because of my dart tips/ Although I will probably go with aluminum with 0.51" or 0.527" ID because I can't find any brass.

Yeah the straw is too thin. I was dispensing silicone into Nerf streamline tips a few weeks ago. I noticed that with a thinner dispenser silicone was dispensed at a slower rate and the velocity they came out at was slower as well.

Wow, darts are getting stuck in longer barrels. Thanks for the info. Now I won't be spending time trying that. I only own a Recon and Stampede(they are both broken). I'll probably make a 3" barrel for the Recon. It's a nice manual, clip system sidearm.

P.S. you're one of my favorite modders. I'm going to get a Longshot sometime this week. I'm going to do your Polycarbonate shotgun grip mod, except with Plexiglass.

Exo: Oh I've never seen the PETG version. I was going to use steel/Aluminum/CPVC because I couldn't find local stores with Brass.

I've never heard of a wye. I've heard of RSCB but I'm not completely sure what it is.

Everyone in General: I'm going to be doing an Aluminum Angel Breech on a Longshot sooner or later.

I've already come up with the blueprints for a blot lock mech on the stampede. If I ever get a new stampede, I may make a write-up.

If I get a new Recon (or a replacement plunger and sled on my old one) I'll try to make a Angel Breech for it. I may try to make it Semi-Auto as well. I've come u with the blueprints for the mechanics and electronics already. I'm not sure if I'll go through with that thoguh. A minimized stampede seems better.