12 replies to this topic

[KiLLa sQuIrR3L]

I was checking out CXWQ's mod on the 750, 3-4 pumps MAX? I pump mine like 8, and it takes like awhile for all the air to leak.

[El Hombre]

Yeah, I go for about 8 pumps on mine as well.. 3-4 pumps seems kinda low to me..hmm. Maybe it's just our 750's?

[cxwq]

Eh... when I wrote the mod I had no clue how much pressure the tank could hold. I'll update it sooner or later. In any event, the gun seems to perform pretty well on just 4 pumps.

[KiLLa sQuIrR3L]

You got 90 feet with 4 pumps?

[cxwq]

A few of the shots went that far.

I averaged 84', 7" with 4 pumps.

If people are super curious I can retest with 8 pumps but that was really just a proof-of-concept mod for PETG. Everyone has done a 750 mod so it wasn't anything new except for the barrel material.

[KiLLa sQuIrR3L]

Can you do that buddy? Is PETG really that good? I get like 50 feet with 4 pumps on my CPVC'ed 750.

[cxwq]

PETG is identical in performance to 9/16" K&S brass.

CPVC is a very poor choice for pump guns because it's a tight fit even with the 'small' 1/2" FBR. In pump guns you ideally want a perfect fit with no effort to slide the darts in.

I'd go with a 5-6" brass barrel sized appropriately for your FBR. PETG would be fine if you can get it in the right size for your darts.

[Grinch]

I pump my PVC breach loaded 750 4-5 times, and I get 91 feet.

[KiLLa sQuIrR3L]

Oh crap, I just blew my airtank on it. i was playing with the rod and I made a cut in the plastic near the air release rod.

What size of PETG do you use CXWQ, my friend is getting some PETG.

[cxwq]

My PETG is .528" ID.

The sizing is different depending on who you buy it from however.

The (mcmaster?) link that someone posted is a different brand of PETG and is thicker walled and sized differently.

I had to look for about a month to find someone with PETG that matched the ID of 9/16" K&S brass.

[LiKnSmAkScOmIn]

so if I buy from the mcmaster site, what size should I buy?

[cxwq]

Measure your darts.

Sorry but that's the only way I can answer your question.

[GunnedDown]

Uhh.. it's pretty hard to measure the ID of your darts when it matters to the 32nd of an inch, especially when most (peice of shit asshat) imperial rulers only go to the 16th's

Likinsmak, what brand FBR do you buy? This may help out. Basically, if your FBR doesn't preform well in Brass, it will preform well in CPVC from the studies I have done. Although the size difference in FBR is quite minute, it matters so much. 17/32in brass is actually too tight for small 1/2in FBR, but CPVC usually fits small 1/2inch perfect; proportionally equivalent to proper 1/2in FBR in 9/16 of an inch brass. It's really confusing, but you can solve it with a logical system of fractions and simplification.