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AirGunEric · Site Admin

Ah- I see what J. is doing- good idea!

Take each coil thickness, .155" and multiply by the number of coils (39) for a total of 6.045". This would be the size of the spring once is it totally, completely 100% compressed and coil-bound.

If it starts at 13.58" and loses at least 5" on compression: 13.58 minus 5 equals 8.58". At 6.045" it's locked, so we have 2.535" of space left between those 39 coils, or .065" which is probably plenty for shooting- but it shows how little space there really is. Someone should measure exactly how much a stock Phantom 500 piston moves from loose to fully compressed and cocked- if it is anywhere near 7" then the Monolith won't work (and at something only slightly less than that- it might be darn near impossible to cock).

Anyone around here have a still-stock Phantom 500 that they can measure the piston travel?

Kevin26 · New Member

it's set. Yeah you'd have to cut it for sure.

daniel sheldon · Member

Just wondeing,, but how fast COULD the phantom get a pellet to go?

23ib0d0n · Moderator

Probably similar to the quest. Mid to high 700f/s in .22 with light enough pellets.

AirGunEric · Site Admin

Mid 700s with 14.3gr pellets have been done apparently (mine only got 710-725fps, but I didn't spend any time trying to coax any more out of it). As J. pointed out, high-700s should be possible with lighter pellets.

Perhaps also low-mid 800s could be gotten with the right spring. For example- this Maccari Monolith with heavier wire. It may not fit "as is" but if you cut it down like Kevin suggested, it would still retain a ton of potential energy once compressed- but unfortunately would also become increasingly harder to compress as it gets cut down. I might wonder if cocking force would be well over 40lbs and if the Crosman trigger would be able to hold it- you might end up with a gun that shoots 14.3gr pellets at 850fps- but would also discharge just by wiggling it!

AirGunEric · Site Admin

Update:

Now that the new modified setup has been in for awhile and I have put about 800 pellets through the gun (dieseling is, essentially, gone)- it has settled down a bit. Using Crosman Premier Hollow Points, which are heavier than the Wadcutters I was using before, the average velocity is about 687fps. Due to the pellet weight change, I believe the output is about 6% less than when first assembled- so not an obscene loss- and still certainly impressive for the minimal mods that were done.

Now on the to CharledaTuna GRT-III trigger install...

Mar · Veteran Member

That is still very decent velocity for a 22, I wouldn't complain if mine did that.

Looks like I won't get my trigger till next week or later, depending on how fast the mail is. Crying or Very sad

Eric did you do anything to the trigger while you had it apart such as smoothing things out a bit?

AirGunEric · Site Admin

I didn't bother with re-arranging the trigger- all the parts appeared to be relatively smooth, and pulling the trigger was smooth- but hard. It appears it is all "in the springs" on my trigger. Actually- it's all in the one spring that sits within the trigger blade itself- it is the one that pushes the trigger forward and comes back to rest on the adjustment screw plate (plastic plate). I didn't feel like trying to bend it all out of shape to see how things changed.

I did install the GRT-III trigger blade on an extra trigger assembly I have laying around- the geometry is totally different and eliminates the hard pull like the stock unit- and that's just from playing with it sitting on a desktop- I really need to get it in the rifle to test out- but I'm extremely optimistic it will work wonderfully. When I install it, I will sand down a couple of parts on the trigger housing where it might (might) rub if the blade gets pushed or cocked one way- no need to wear out the aluminum trigger blade too quicky!