How many shots?

P4p3Rc1iP · 01-11-2008, 07:45 PM

How many shots should I roughly expect to get from a 3,5 oz tank on a stock VM?

50? 100? 150? I doubt it'd be more than 150, right?

Tohri · 01-11-2008, 08:16 PM

My VM with a properly tuned valve gets about 500 off a 9oz.
So, Extrapolated, probably around 200, if you properly modify the valve.

P4p3Rc1iP · 01-11-2008, 09:05 PM

What do you mean by "properly mod the valve"? Are there any guides for this stuff?

Tohri · 01-12-2008, 09:49 AM

Egh. I really need to remember that not everyone is an obsessive airsmith.

Basically you want to port the Valve, The receiver, And the bolt for enhanced flow.
Bore out the vent holes on the VM's Valve to 1/4'-5/16' (I forget) And match the hole in the VM's body to that. (You may be able to go Bigger, god knows the VM has enough meat on it to stand big holes in it) And if you have access to a Lathe, cut a 1/8" groove around the valve, over the vent holes.

This will cause a dropoff in blowback gasses, So a 1/16" hole will need to be drilled through the back of the valve to the exhaust area (Where you drilled the holes) Avoid the retention screw holes on your way, And possibly tap the receiver for a setscrew, to adjust the additional flow.

This should give you much improved gas efficiency. The reason this was not done at the factory was because the different sized ports gave a rough velocity adjustment, and 100% reliability on Co2. Today we use regulated HPA, and as long as your blowback to Bolt exhaust ratio is the same, You'll be all set.

DRAGON · 01-17-2008, 04:24 AM

tohri if i dont run the groove around the valve and still put the hole through the valve will it work and can you post a pic to show where the whole through the valve goes i think i know but i just want to be sure

thanx

Anonymous Coward · 01-17-2008, 05:58 PM

I say go the opposite direction.

Aim to use as much CO2 per shot as you can and stay underneath the field's FPS. The louder the better. The bigger the CO2 cloud the better. And the harder the kick the sweeter she is.

I'm telling ya, you can either shoot a BB gun or a harpoon. I opt for the harpoon.

Tohri · 01-18-2008, 10:12 AM

If you just drill the Largest hole on the valve's circumference out, You don't need to add more porting to the hammer to compensate, But you won't get maximum flow.

There is another choke point here as well, The hole in the receiver between the hammer/Valve tube, and the bolt/Barrel tube. Bore that out from the top (There is a setscrew where the hole was drilled at the factory) At the same size as the Valve's new hole.
Make SURE you have a good quality drill press to do this on. do not attempt to hand drill these, you'll almost surely ruin parts. Three whole guns have been killed by my hand, and countless parts while I was learning.

DRAGON · 01-18-2008, 05:30 PM

ok i have the valve,the transfer port and the bolt drilled out to 5/16 i think and i dont have enough bolwback air to recock the hammer most of the time
so i was wondering about this part of your post

"This will cause a dropoff in blowback gasses, So a 1/16" hole will need to be drilled through the back of the valve to the exhaust area (Where you drilled the holes) Avoid the retention screw holes on your way, And possibly tap the receiver for a setscrew, to adjust the additional flow."

just wondering where to drill this hole and if it will help

thanx

dragon

Tohri · 01-19-2008, 04:36 PM

Drilling the hole will certainly help.

Here's what you do: Put the cup seal on the valve, so you don't mar the valve seat, and put it in the Drill press's vise, Cupseal down, Valve stem up, with the 5/16" hole you ported in the 12 o clock position.
The 1/16" hole should be drilled in through the back of the valve (Where the hammer hits) into the middle of the valve, tapping into exhaust gasses. Use your best judgement on this, As there is a 10-32 retention screw hole in line with the exhaust orts. Not certain if drilling through these would be a good idea, but if you don't have the slot cut around the Valve's circumference then you'll probably have to put the hole there.
Bump it up to a bigger port if the 1/16" doesn't give you enough oomph, You can always put a setscrew in the valve retention port to restrict flow.

DRAGON · 01-20-2008, 04:53 AM

ok thanx ill give that a try

01-11-2008, 07:45 PM	#1 (permalink)
P4p3Rc1iP Seasoned Member Join Date: Aug 2006 Location: Leeuwarden, The Netherlands	How many shots? How many shots should I roughly expect to get from a 3,5 oz tank on a stock VM? 50? 100? 150? I doubt it'd be more than 150, right? __________________

01-11-2008, 09:05 PM	#3 (permalink)
P4p3Rc1iP Seasoned Member Join Date: Aug 2006 Location: Leeuwarden, The Netherlands	What do you mean by "properly mod the valve"? Are there any guides for this stuff? __________________

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

01-11-2008, 08:16 PM	#2 (permalink)
Tohri 65%More Bullet Per Bullet Join Date: Jul 2006	My VM with a properly tuned valve gets about 500 off a 9oz. So, Extrapolated, probably around 200, if you properly modify the valve.

01-12-2008, 09:49 AM	#4 (permalink)
Tohri 65%More Bullet Per Bullet Join Date: Jul 2006	Egh. I really need to remember that not everyone is an obsessive airsmith. Basically you want to port the Valve, The receiver, And the bolt for enhanced flow. Bore out the vent holes on the VM's Valve to 1/4'-5/16' (I forget) And match the hole in the VM's body to that. (You may be able to go Bigger, god knows the VM has enough meat on it to stand big holes in it) And if you have access to a Lathe, cut a 1/8" groove around the valve, over the vent holes. This will cause a dropoff in blowback gasses, So a 1/16" hole will need to be drilled through the back of the valve to the exhaust area (Where you drilled the holes) Avoid the retention screw holes on your way, And possibly tap the receiver for a setscrew, to adjust the additional flow. This should give you much improved gas efficiency. The reason this was not done at the factory was because the different sized ports gave a rough velocity adjustment, and 100% reliability on Co2. Today we use regulated HPA, and as long as your blowback to Bolt exhaust ratio is the same, You'll be all set.

01-17-2008, 04:24 AM	#5 (permalink)
DRAGON Newbie Join Date: Apr 2007 Location: ontario	tohri if i dont run the groove around the valve and still put the hole through the valve will it work and can you post a pic to show where the whole through the valve goes i think i know but i just want to be sure thanx

01-17-2008, 05:58 PM	#6 (permalink)
Anonymous Coward Active Member Join Date: Jul 2007	I say go the opposite direction. Aim to use as much CO2 per shot as you can and stay underneath the field's FPS. The louder the better. The bigger the CO2 cloud the better. And the harder the kick the sweeter she is. I'm telling ya, you can either shoot a BB gun or a harpoon. I opt for the harpoon.

01-18-2008, 10:12 AM	#7 (permalink)
Tohri 65%More Bullet Per Bullet Join Date: Jul 2006	If you just drill the Largest hole on the valve's circumference out, You don't need to add more porting to the hammer to compensate, But you won't get maximum flow. There is another choke point here as well, The hole in the receiver between the hammer/Valve tube, and the bolt/Barrel tube. Bore that out from the top (There is a setscrew where the hole was drilled at the factory) At the same size as the Valve's new hole. Make SURE you have a good quality drill press to do this on. do not attempt to hand drill these, you'll almost surely ruin parts. Three whole guns have been killed by my hand, and countless parts while I was learning.

01-18-2008, 05:30 PM	#8 (permalink)
DRAGON Newbie Join Date: Apr 2007 Location: ontario	ok i have the valve,the transfer port and the bolt drilled out to 5/16 i think and i dont have enough bolwback air to recock the hammer most of the time so i was wondering about this part of your post "This will cause a dropoff in blowback gasses, So a 1/16" hole will need to be drilled through the back of the valve to the exhaust area (Where you drilled the holes) Avoid the retention screw holes on your way, And possibly tap the receiver for a setscrew, to adjust the additional flow." just wondering where to drill this hole and if it will help thanx dragon

01-19-2008, 04:36 PM	#9 (permalink)
Tohri 65%More Bullet Per Bullet Join Date: Jul 2006	Drilling the hole will certainly help. Here's what you do: Put the cup seal on the valve, so you don't mar the valve seat, and put it in the Drill press's vise, Cupseal down, Valve stem up, with the 5/16" hole you ported in the 12 o clock position. The 1/16" hole should be drilled in through the back of the valve (Where the hammer hits) into the middle of the valve, tapping into exhaust gasses. Use your best judgement on this, As there is a 10-32 retention screw hole in line with the exhaust orts. Not certain if drilling through these would be a good idea, but if you don't have the slot cut around the Valve's circumference then you'll probably have to put the hole there. Bump it up to a bigger port if the 1/16" doesn't give you enough oomph, You can always put a setscrew in the valve retention port to restrict flow.

01-20-2008, 04:53 AM	#10 (permalink)
DRAGON Newbie Join Date: Apr 2007 Location: ontario	ok thanx ill give that a try