8 replies to this topic

[deaddumpster]

Now, this is not new at all. I discovered it a little over a year ago now and I thought it would be a good idea to share it with the world. Some of you may recall my SM500 at Massacre 3, which had this breech in it.

What you will need:
- PETG from OMC (Length depends on what blaster you plan on using it in)
- 1/2" Sch. 40 PVC (Same length as your PETG)
- 2" of 5/8" brass
- A 1/2" PVC coupler
- Adhesive of your choice (I used good ol' Goop and Fishin' glue)
- Electrical tape
- Pipe cutters
- A hobby knife
- A rotary tool
- A cutting wheel for said rotary tool, strong enough to cut brass
- A 5/8" diameter grinding wheel, also for the rotary tool
- A rubber mallet
- Sandpaper (To make your cuts smooth)
- Needlenose pliers )Optional, but extremely useful)
- Measuring tape
- Sharpie to mark where you plan on cutting


Measure 1.5" down from one end of your PVC pipe. Take your Sharpie and put a dot on the 1.5" mark. From that point, measure out 2" or so (Slightly longer than your Stefans). Draw a line along the 2" and trace out the rest of the half-pipe:


Bust out your rotary tool (Or what ever you use to cut) and cut along the lines. Try to clean it up with a hobby knife and sandpaper:


Now, take that piece of 5/8" brass and measure 1.5". Mark it down and then put another dot about 1/2" ahead of it:


Take your pipe cutters and put two or three tightening rings in the 1/5" piece. Be careful, and check the fit on the PETG often. You want it to have a good seal, but you also want to easily pull it out as well. Once you're done, put a very light ring around the 1/2" long piece:


Cut where you marked:


Take the 5/8" grinding/sanding wheel and sand out the PVC ALMOST up to the half-pipe. Be very careful and try not to make the hole too wide:


Take your rubber mallet and hammer it in until the brass is almost flush with the PVC. Be sure to use a rubber mallet, or else the brass will deform when you hammer it:


If you have made it this far, awesomesauce work. Now we're going to go to the other side of your PVC pipe. Cut about 2" off that end with your pipecutters:


Get your mallet again and hammer the PVC completely through the PVC coupler. An alternative would be to just sand out the ring in the middle of the coupler, but I was lazy:


Take your e-tape and wrap it around one end of your PETG. Apply Goop and put your PVC+coupler over it:


Leave it to dry.

Once again, go to the side opposite the half-pipe. This time, use your 5/8" wheel and sand about 1/4" in:


Place the 1/2" long piece of 5/8" brass in:


Get your mallet and hammer it flush with the PVC. This will keep the PETG barrel from flying out when the breech is opened:


Take your two parts and put them together:

Edited by deaddumpster, 18 March 2010 - 03:22 PM.

[deaddumpster]

Breech closed:


You're done motherfucker!

Pros:
- Lighter than an all-brass breech.
- Very sturdy.
- Can be glued on to any blaster or placed in a PVC coupler.
- Simple, so pretty much anyone can make it.
- Cheaper than an all-brass breech (1' of 5/8 brass=6 of these breeches)
- PETG, so you can tell if there's a dart in the barrel.
- Pretty damn sexy if it's clean (Though mine is not)

Con:
- Even with the tightening rings, a TINY amount of air escapes between the PETG and the brass. There isn't any noticeable decrease in range, though I know it's still going to do something.

PS. I really want a new camera.

Edited by deaddumpster, 18 March 2010 - 03:31 PM.

[jakejagan]

Nice write-up. You could use 17/32 brass to help with the seal. I made one like what I said and it is airtight.

[Lt Stefan]

So... What's the point of all the extra work/brass?

[Griff Zombie]

So instead of having 3 layers of moving internals, you simplified it so the breech ''advances'' by moving the outer layer/cover instead of an internally rigged ''bolt''?

Edited by Griff_Zombie, 19 March 2010 - 02:58 PM.

[jakejagan]

So... What's the point of all the extra work/brass?

It increases the air seal. 17/32 brass seals very well with petg.

[Lt Stefan]

So... What's the point of all the extra work/brass?

It increases the air seal. 17/32 brass seals very well with petg.

I know... But that's all been done before?

[Hi Yah]

Why not just use e-tape to allow the PETG to slide in the PVC, instead of the brass?

[Broderick]

Why not just use e-tape to allow the PETG to slide in the PVC, instead of the brass?

Electrical Tape wears out and smears black gunk inside your PVC? The brass won't wear down, but e-tape does allow you a more "play it by ear" sort of air seal.
This is a good alternative to the normal route though, I like it. It seems like it'd just last longer, and be more sturdy. The PETG breech I'm using after minimal use seems... I don't know, sort of flimsy with E-tape being the only spacer in between the moving PETG and the PVC.

Edited by Broderick, 20 March 2010 - 11:19 PM.