My 98C is jamming

I've got a 5-6 year old 98C (SN: 476,xxx); polished receiver, R/T, Cyclone Feed, Super-fly front bolt, BT spring kit.  All other internals are stock.

The last few times I've played, I have had a rare issue of the gun jamming just short of the cocked position.  It seems like the sear is actually grabbing and holding the hammer just short of the notch.  The rear hammer is about 95% of the way back, but again, not actually fully cocked.

This hasn't happened very often, maybe once or twice a day.  I haven't noticed any kind of conditions that cause this.  I can tell you that it has happened on both a full tank, and partial tank.  Also, when disassembled, the gun parts don't have any unusual wear, and all seem to able to move freely.  The sear & hammer notch are actually in pretty good condition for as old as they are.

Today, I plan to slightly sand & smooth the bottom of the hammer, but I can't think of anything else that would be causing this problem.


Edited by motopsycho650 - 30 March 2008 at 4:49am

Yet another problem caused by silly front bolt 'upgrades'.

ammolord wrote: wow, why would you even mess with the bolt?

The only benefit I really believe in is the cupped shape in the front.  It has much more contact area with the paintball, and ensures the ball centers it's self in the bolt while being pushed.  The stock bolt on my old Pro/Carbine has a partial cup molded into it, but the 98's went to a flat bolt that only contacts the ball in a small ring at the center.  I really do believe the cupped shape helps prevent ball breakage.

I bought the Super-fly because I wanted to see if the inner o-ring really made a difference.  Well, odviously it did without being set up correctly.  1st off, when I got it, it was way too snug with the stock powertube.  This was because of the rough plastic molding on the powertube.  I sanded it down & smoothed it.

2nd, I learned this morning that the powertube is not perfectly centered in the receiver.  In both my 98C & M98, it sits pulled towards the feeder side where it's attached.  I figured out that 1 small strip of electrical tape next to each powertube bolt hole is almost the perfect shim to center the powertube.  The stock bolt has some slop between it & the powertube, so the non-centered valve is probably overlooked.

I am not 100% sure I've fixed my issues, but it makes sense.  Like I said, the internals did seem more freely able to move.


Edited by motopsycho650 - 30 March 2008 at 10:39pm

Try replacing the hammer o-ring.  If that doesn't work try adjusting the reg to increase input pressure.  This will decrease efficiency, but increasing the input pressure combined with using the front velocity adjuster to bring the velocity back down will have the effect of increasing the "back pressure" in the marker that resets the hammer.  (I can't guarantee it will work, but it is worth a try.)

oldpbnoob wrote: I thought I read somewhere that Tippmanns are supposed to run with 750-800psi?

I've read that too.  Here's the thing.  A 98C is sold as an unregulated CO2 powered gun.  Using CO2, and no regulator, it is impossible to have your gun run between 750-800psi unless the out side temp is between 60-70 degrees out.

I read from tippmann, that the CVX valve was designed to work at a pressure range of 350 - 1200+ psi.  That is much more realistic considering temp changes & CO2.  The 750-800 psi range is what they consider to be the best operating pressure.

I'm running a Palmer's Stabilizer, a harder main spring, and have my stock velocity adjustment turn out pretty far, (Farthest out while still being able to split the receiver).  I have been using my stabilizer adjustment as my velocity adjustment.  I have great consistency, and save quite a bit of air because I'm adjusting the input pressure for velocity, not the output pressure which wastes air.

I think my problem has nothing to do with pressure.  The other 1996/2000 shots re-cocked just fine.  The 4 shots that jammed, I believe is something inside binding up.

Some one on specialopspaintball.com suggested I have the receiver bolts too tight.  That makes more sense to me that anything else.  Before the weekend, I'm thinking I'll try spacing the two receiver halves with a piece of electrical tape at strategic locations.  That should eliminate any possibility of things being too tight and binding.  If that doesn't work, I'll try upping the psi to the 700-800 range.

P.S.  Tippmann's customer service dept. has not returned my email in over 48 hours on this issue.  And on a previous R/T problem, they provided me with a blow-off answer...  What happened to the legendary Tippmann Customer Service Dept. from 5 years ago???

I'm getting annoyed enough at my 98C, that I've thought of going to Wal-mart & buying a new one.  The problem is, they have changed the design so much, most of my upgrade parts won't fit the new 98C's.  i.e. All my barrels are old style threads, etc.  Now with the Platinum edition 98C's, there will be even more "New Style" upgrade parts.


Edited by motopsycho650 - 17 April 2008 at 7:49am

thejudge wrote: I suggest upping the pressure and then using the actual velocity adjuster to adjust velocity.  The extra pressure should help solve your problem.

Hmmm . . . this seems familiar . . . just can't put my finger on where I've seen this before.

We'll see...  I'm playing on sunday.  Problem is, what if the temp won't support 800 psi...  I am in colorado, and it's still April.

I don't know.  I never had this problem before it was stored for 3 years while I recovered from a broken femur.  Since then, it happened before I added the palmer's, cyclone, or spring kit mods.  I am playing enough now to where I really want to figure this out.

I will try both ideas on Sunday, and report back...

I understand fully what you guys are saying about the pressure.  I know it's cause & effect on re-cocking.

The pressure still doesn't answer my question, Why is it jamming???  If it was nothing but a pressure issue, then why isn't my gun double firing, or making the "out of air" fart noise?

Like I said, I understand fully what you guys think about the air pressure.  But, that CAN'T be the only problem.  Something has to be binding inside for the internals to get stuck partially cocked.  Pressure, or lack of pressure will not cause jamming by it's self, so what is the OTHER cause???

I'd be willing to bet money, than I can go remove my regulator, screw a heated tank straight into my gun, so that it would be getting over 1000 psi, and it will still jam.  I know this because it did BEFORE I added the reg and lowered the pressure.

Before I broke my leg, it shot flawless, at 100 degrees, at 30 degrees, it didn't matter what the pressure was.  As soon as I pulled it out of storage, it jams.  None of the additional mods I have added since then have effected the jamming, whether it be the regulator, the spring kit, etc.  It jammed before I added them, and it jammed after I added them, so therefore, they can be eliminated as a cause of the problem.

Tippmann finally wrote me back, they suggest loosening the receiver bolts as-well.  Other than that, they said, "we're not sure what else could cause this, check your hammer & sear for wear."  It's not a good sign when the guys who built the gun don't have a clue...

P.S.  I have read lots of articles, as well as played with people who have their 98C's running less than 600 psi without the LPK.  Pressure times flow equals velocity.  If you lower the pressure, and increase the air flow (i.e. heavier spring to hit the valve harder), you can get the same 300 fps as a stock gun.  There is actually a science to it, matching the pressure to the outside temp to prevent shooting solid...


Edited by motopsycho650 - 18 April 2008 at 2:20pm

i dont know if this was asked or not but are you running co2 or HPA?  i assume co2 if it is that finicky in cold weather.  Try HPA for a day if you can.  see if that helps.