Air Gun Home :: View topic - interesting finds on 2 week old phantom 500

dscott77 · Member

so after tons of research on this site i decided to give my phantom a lube tune and maybe a spring mod. As i was taking everything apart i notice that blue loctite has been applied to all screws from factory. Very Happy

As i get deeper into the guts there are very little defects ie. metal shavings crap lube an so on. Its actually been machined rather nicely. Oil instead Chinese grease. Impressed so far none of the horror stories ive read.

Now the part that got me Question

My piston cannot be modified because it already is from the factory.

The piston measures in a 150mm

so im thinking how did they detune this
heres how i think

there is a small hole drilled in the top of the piston

and next the tophat

there are air ways machined in it .

As well from what ive read on line there should be 35 -37 ciols in the spring mine has 34.

So what does everyone else think?
Dave

AirGunEric · Site Admin

I had not, up until this post, seen the modified top hat and drilled piston. I guess it's a fair bit cheaper than having a completely different spring and piston in the '500' rifles.

The spring with 34 coils may not be that significant- the usual/former "detuned" spring would often have 30-31 coils, and the newest "full power" springs have 35 coils. Your coil count may also be different by one coil depending on how you counted them- I suspect the spring is not modified from the full-power version.

It means very little from the upgrade point of view, other than not being able to cut the piston, it now must be either sealed effectively or a replacement piston purchased- i.e. essentially about the same amount of effort as previously, but a bit different.

Interesting find, however!

dscott77 · Member

I think im going to see if i have an o-ring that might fit inside the tophat to seal up the air flow see what happens. I dont have a chrony to get accurate numbers but i did some before shots at a 2x4 if i can seal it up ill do some after shots to see what the penetration difference is. But it time for dinner so
later tonight ill post results.
Dave

Brutuz · Senior Member

Like the bleed hole in the valve of my 2289G backpacker Twisted Evil

Hope your mod works, mine did Mr. Green

kanyon · Silver Status Member

That hole would be welded real quick if it was mine...

tap a tread in it & loc tight a set screw in...

Pete

Amigo · Veteran Member

dscott77's location (country) is not given. Airguns intended for Canadian & U.K. markets, as I believe the 500 series are, may be "de-tuned" to comply applicable law.

Ref: Crosman C1K77 mainspring
Crosman Rifle C1K77 series Spring Spec's. (Quest1000, Sierra Pro, Storm, Phantom 1000, Tac 1 Extreme & Remington Summit models):

Coils=36 (full, no partial)
Wire size=.121" +-.001
Length=10 1/4"+- 1/32" Free Length new unset.
Inner diameter=.487" +-.003
Outer diameter=.732"+- .003 O.D.
10.25" divided by 35 (36-1) equals .293 pitch
(.170" coil space + .122" wire dia. =.292 unit pitch)

Unless Crosman spec's. have changed in the last 6 months, the above spring spec's. should still be accurate for rifles intended for the U.S. market.

BTW, unless my old eyes are deceiving me photo #2 appears to indicate a "bleed" hole in the center of the piston seal, while photo #3 looks like the end of the piston with the seal removed and not what is commonly referred to as a "top hat".

Hope this helps,

Amigo

AirGunEric · Site Admin

Picture #3 is the upper spring guide, or "top hat" which has obviously had those channels machined into it to allow the venting from the piston to flow past.

dscott77 · Member

Hey Amigo,
Eric is right pic# 3 is the top hat ( its sitting in the spring for the pic)

So just for testing purposes (before i go and do any permanent changes) I found an o-ring that fits inside the top hat, reinstalled everything and did a couple of test shots on a 2x4 that i shot previously at about 30 feet :
before the o-ring crosman pointed pellets just broke the surface with about 2mm of the skirt sticking out. After the o-ring was installed pellet is going 3/4's the way through. Clap Clap

I forgot to take pictures so im going to take it apart again to take some quick pics. Now I'm trying to figure out do I want to leave the rubber o-ring or do something more permanent.
Dave

rsterne · Moderator

Unless I don't understand the photos.... if you plug the hole in the end of the piston.... then the air in front of the seal can't make it back to where the top hat is anyway.... correct?....

Bob

AirGunEric · Site Admin

dscott77 · Member

gonna plug the hole today

fritz · Silver Status Member

Be warned: if that does increase the average fps above 500, then you have a firearm on your hands (in Canada). Please do not do so unless you have your firearms permit or other required legal documents.

dscott77 · Member

So for testing purposes this is what I did

Shooting extremely well as previously stated.

Checked the mail today and my new seal and moly arrived so I tore the gun apart again redid the lube job plugged the hole and installed the new seal

pic of new seal installed and hole plugged with set screw and loc-tite ( pic not very good)

Seal was a nice tight fit, everything went together nice.

Now time to go through a tin or two of pellets to settle everything in and report back. Dam I need a chrony. Rifle seems to be shooting harder than stock but not as hard as with just the o-ring in the top hat. Anyways off to shoot some targets.
Dave

AirGunEric · Site Admin

dscott77 · Member

Dam I wish I was a ware of that before. Thanks Eric. I guess for a $100 rifle crosman is building some thing decent these days. I have come across none of the problems that I have read about ie. bad machining, loc-tite, breech seal,barrel pivot, and the Chinese lube. I really like this gun out of the box. I kept my old seal so I'm going to put it back in and see if anything changes.
I would highly recommend the phantom 500 to anyone wishing for a cheap accurate rifle. It is easy to work on and with all the improvements on this rifle very little needs to be done. Lube it and Shoot it.
Dave