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daniel sheldon · Member

Ya I could cut some pistons down for some people.Not a pro, but not a problem.

AirGunEric · Site Admin

airbuddy3 · Member

Good job Eric ,
some decent numbers there , that was with a quest 1000 piston 2 washers and a Tarantula spring ?

Daniel .. good job there too .. you CAN Stroke it more and get more swept volume but you will have to modify Other parts of the rifle too
and gains will be hard earned ..but 7xx is doable Wink

Frank

AirGunEric · Site Admin

Hello Frank, those numbers are with the stock Phantom spring. The Tarantula spring I took out when it compressed and shrunk about 2"- as I hadn't realized it wasn't pre-set beforehand. I have another gun to put the Tarantula in, but haven't gotten to it quite yet.

Perhaps putting in the Tarantula would up the power a bit more but I also wanted to see how the factory-supplied spring would do on its own.

airbuddy3 · Member

Hi Eric ,
I have gotten similar numbers with the factory supplied spring , they seem like a decent spring ... we will know with time how well they stand up to use . I like the thicker steel 85 thou of the newer pistons as this contribues to the mass of the piston ( there is only so much space for added mass ) .
By supplying the full length piston ..you are getting a blank slate for modding Laughing

the Amercan guns never got that Laughing

there are other areas that allow greater stroke volume ..but it becomes more tecnical and more difficult . but the high 600's to low 700's are relativly easy to get as the gun has a lot of swept volume .

I have found that for every square inch of swept volume ( all else optimised ) you can get~ 3.5 ftlbs of energy .
so that why your HW 45 pistol and its 1.7 inches of swept volume gets a bit over 6 ftlbs energy , and a rifle like the B19 /quest /phantom
that has 4.5 sq inches of swept volume gets 15 fpe +
and more can be got by further increase in volume .

Frank

AirGunEric · Site Admin

I see what you're saying- very useful.

As for the Phantom piston having a greater wall thickness than those of the Quests- I think that may only be true for the ones put in not-so-recent production Quests. The brand-new Quest 1000 piston I have been using, which I got from Crosman 8 or 9 weeks ago seems to be the same thickness as the one on the Phantom- so the factory may have changed all of them and the newest Quests will also be seeing them if they haven't already.

I think that's part of the problem- comparing 2 or 3 year old guns to the 'newest version' and saying "look at all the wonderful improvements"- which may in fact have been added incrementally throughout the guns production history.

daniel sheldon · Member

no I didn't do anything else ,Cut 2 inches off ,the catch hole is in about the same place.Didn't do any exact messuring so i might have taken a bit more off.nuthing major though

AirGunEric · Site Admin

No problem! I need to get me some of those Superman "X-Ray vision" eyes to see things (the spring compressed inside the tube). I could figure that out when the gun's apart again by measuring things. I never thought the spring would be brought to an almost coil-bound condition with these mods!

Kevin26 · New Member

This thread is a good read. Nice work. Yes you can lighten the piston, and increase the stroke, OR you could go the other route. Which would consist of puting the THICKEST airgun spring you can find, the "Monolith Kodiak -Patriot Spring" measured at .148 inch. With its thickness and awesome energy retention, piston weight/lengh become irrelevant. The stroke doesn't need to be increased, the thickness of the spring compensates for thinner springs that need stroke. Razz

AirGunEric · Site Admin

Where can a "Monolith Kodiak Patriot Spring" be found so I can see some specs on it?

Kevin26 · New Member

At "Air Rifle Headquarters"

AirGunEric · Site Admin

http://www.airguns.citymax.com/catalog/item/251488/43385.htm

Ah OK- that's Jim Maccari. Unfortunately, he doesn't list his springs by specs, but usually by application- so the Kodiak-Patriot spring states the wire diameter like you posted- but not the actual installed/compressed height or the outer diameter!

Using JM's usual terminology/labelling, the spring is named a "Monolith" by JM and used in a Beeman Kodiak or a Webley Patriot.

Perhaps we can find a source for data on the stock spring used in one of those guns? That would help give us an idea of the installed height anyways.

Kevin26 · New Member

Here's what I found out the "Monolith" is actually at .155 inches (thicker than ounce thought) after being checked with micrometer. The number of coils: 39 Length: 13.58 inches Outside coil diameter: .887 inch Smile

I hope this is helpfull.

AirGunEric · Site Admin

Do you know if that 13.58" is already "set" or "unset". If that's its set length- it is likely too long to fit inside a Phantom 500. When installed- there is approximately 10" of space in the Phantom 500 tube for the spring, so at 13.58" it's already compressed 3.58" and needs another 2" or so for the gun to cock even using the stock Phantom 500 piston- so that's over 5" of compression and I wonder if that spring is able to do that? It may be, but someone should try it out before everyone makes a mad rush to buy monolith springs!

23ib0d0n · Moderator

39 x .148" = ~ 5.8" coil bound.