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|03-24-2017, 12:30 PM||#11 (permalink)|
THE Green Modster
I've talked about and messed with Nelsons looking to get more efficiency/consistancy A LOT and read a lot about snipers on 12ies but have little experience with those.
A few notes from my experience:
Regulating seems to offer the best results for snipers since there is so much volume there already.
The animation of the Phantom you posted and your valve question - the back 50-60% (Shot in the dark not an actual measurement) of the valve has very little volume to it as it's almost completely solid just an air passage to accommodate BBA. The front is wide open.
Instead of looking to Phantoms/Nelsons for your inspiration I would suggest looking to the work that guys like the Palmers, Stuffy, Rainman and some others have done on KP's and PGP's. It's a much closer relation to start with and I know that Stuffy and Rainman have put together guns that shoot 45-50+ Shots on a 12ie without a reg.
Don't ignore Heat! If the temp of the gun stays consistent so does the expansion of the CO2.
When I ran the idea of running liquid out of a 12ie by Mike C he agreed with me that there is not nearly enough liquid in a 12ie to make it work consistently.
Master Jar Jar
|03-24-2017, 12:31 PM||#12 (permalink)|
Join Date: Dec 2016
Location: Pburgh (formerly a New Englander)
Responding to pancake's post: I have a flat velocity curve with Palmer's "Sniper valve" for unregulated CO2, I run a 3.5 oz tank vertically and get 200 shots or a hopper's worth with only the last 6 shots being below 250. I had to use the hardware store spacers to fill in the pre-valve chamber to do that and also a spacer to increase valve spring tension
Here is that valve: https://palmerspursuit.com/products/...ssembly-sniper
I think this is it but cheaper: https://www.baccipaintball.com/aut1830.html
Last edited by Pittsburgh Stinkbugs; 03-24-2017 at 12:39 PM.
|03-24-2017, 12:42 PM||#13 (permalink)|
Join Date: Dec 2008
Location: Houston, TX
For a low pressure Nelson project, search for the bullfrog Nelson. Stock phantoms are fairly well sweet spotted. There's a higher pressure involved with unregulated co2, so the springs and weights are higher.
If you get hot first and second shots out of many, that is more about high flow from piercing and partially wet co2. For this you need to restrict the flow from the changer to about a pin hole.
After that watch for rise or drop at the end of the 12g. Long droop says you are too heavy on main spring or hammer mass. You are smacking the valve full open all of the time. A spike near the end says you are floating the valve, but your dwell is going up too much as the pressure goes down. This is usually the mainspring has too much preload, where it still has too much push left after the hammer has made contact. Try to let the mainspring adjustment fling the hammer more than it holds the valve open, maybe going to a heavier but shorter spring.
You can also over size the poppet seal to create more drag if you get stuck with a big hammer and need short dwell for a short barrel.
some things are stickier than others
|03-24-2017, 01:00 PM||#14 (permalink)|
Green - I'll look into the Palmer's stuff, thanks, also thanks for your input on the phantom animation. I understand rugged is easier/more control over the system but I'm solely going for an unregged setup
Stink - thanks for the info, I currently have that valve installed because I also heard it gives good results. I'd love to run a 3.5-4oz tank but my field does not do refills. It helps get more shots off before worrying about the pressure changing from depleting the source. It's also just plain fun to change some 12ies!
Spider - I was hoping you'd come around!
"watch for rise or drop at the end of the 12g. Long droop says you are too heavy on main spring or hammer mass. You are smacking the valve full open all of the time. A spike near the end says you are floating the valve, but your dwell is going up too much as the pressure goes down. This is usually the mainspring has too much preload, where it still has too much push left after the hammer has made contact. Try to let the mainspring adjustment fling the hammer more than it holds the valve open, maybe going to a heavier but shorter spring."
Thanks for the awesome explanation, this is the kind of information I was hoping for. I see what you mean and have noticed that there is more consistency in "flinging" the hammer rather than still having some push left over, so I will look for a good balance of strength and shortness in a main spring.
The pieces of the puzzle are there, just need to get them in the right places! Thanks all for participating!
|03-24-2017, 01:27 PM||#15 (permalink)|
Valve spring - must be stiff enough to have operating pressure of the CO2 cartridge. If operating pressure for that spring is below that of the CO2, velocity may increase as source is depleted. If operating pressure is at or above that of CO2, it can have more consistent dwell over the duration of the 12ie.
Hammer spring - stiff enough to give the hammer enough momentum to open a valve against a CO2 rated valve spring, but short enough to just "fling" the hammer but not long enough to push the hammer once it is in contact with the valve. If the hammer spring is too long, that "dwell" from the hammer spring directly pushing on the valve will increase as pressure decreases and causes hot shots towards the end.
If it comes down to it, I'd love to order some specific springs from some spring company that are matched for these setups. Does anybody know a spring company that does custom orders on the order of 50 units or so?
I'm going to see what a 12ie pressure is (I think 850 or so), and then test the pressure vs velocity curve of my red maddman spring using HPA through a high pressure stabilizer to see if the relative maximum velocity is at a pressure around or above that of the 12ie to find out whether velocity will increase or decrease throughout the duration of the 12IE. In previous tests it has increased, but I know for a fact I had the hammer spring pre-loaded too much and it was participating in opening the valve more than just flinging the hammer.
Once I find a valve spring where velocity will decrease (hopefully marginally) as the pressure increases, it will be time to find a mainspring as described above.
What are your thoughts on the effect of a heavier hammer? I read that they can cause some hammer bounce and reduce efficiency
|03-24-2017, 01:54 PM||#17 (permalink)|
Well fine tuned is what we're going for since the system is so sensitive 24 shots off a 12IE is good but more is definitely possible. That efficiency may be a result of the reverberation and lost air from that.
|03-24-2017, 01:58 PM||#18 (permalink)|
Join Date: Dec 2016
Location: Pburgh (formerly a New Englander)
I erased what I wrote because you covered that you're looking for a hammer and spring that won't try to push beyond the valve pin after its opened
In my case I gave up tweaking my particular setup when I met the goal I wanted from it
If your goal is to get 35 shots I recommend killerito's setup with his regulator, etc.
Even down to the horizontal ASA and the hose
Last edited by Pittsburgh Stinkbugs; 03-24-2017 at 02:04 PM.
|03-24-2017, 02:16 PM||#19 (permalink)|
Again, I'm aware of the success of regulated setups but that is not what I am going for.
Side thought - does the travel of the valve stem play a big role in shot to shot consistency? Does the flange on the CCI valve stem physically restrict travel of the valve stem or does it not bottom out? What I'm getting at is that maybe chopping an eighth inch or so off of the Palmer's valve stem would reduce variation in valve stem travel distance enough to reduce the effects of pressure change, or even effects of mainspring pushing on the valve
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