Avery
03-12-2002, 12:12 PM
I have a 98c with 2nd Gen GTA XP, RT, carefully polished internals, lapco bigshot and other unimportant upgrades. The internals are stock other than the RT power tube. My velocity blows. I can't get it over 270. Here's the scoop:
Using two borrowed stock 98s and my own I did a little testing at the same time, with the same paint, the same CO2 and the same HPA tanks, the same barrel, the same hammer springs, the same place, the same chrono. The other 2 guns shot 100 fps faster than mine. I took off my XP chamber and got a drop in velocity of 10 fps, so it's not the XP. I took off the RT and screwed in the plug, it's not the RT. It's not the weather, gas or barrel or paint. I've also replaced the rear hammer oring without improvement. I've also bought the Madmann Spring Kit and put in the heaviest spring and actually lost a few FPS.
So... either the valve is crappy (although it's new straight from Tippmann) or my bolt(s) are getting hung up on the receiver. The rear bolt is scraping the left receiver half pretty badly, leaving scored gouges above and below the cocking slot. Could the hammer be striking the valve too weakly because of this? Tippmann says this kind of scoring and scratching is normal.
I'm running HPA at 850 psi now and still only getting 280 FPS (which is fine, but that's wasting a lot of air to get that velocity at such a high pressure).
Any ideas what to do?
Avery
Using two borrowed stock 98s and my own I did a little testing at the same time, with the same paint, the same CO2 and the same HPA tanks, the same barrel, the same hammer springs, the same place, the same chrono. The other 2 guns shot 100 fps faster than mine. I took off my XP chamber and got a drop in velocity of 10 fps, so it's not the XP. I took off the RT and screwed in the plug, it's not the RT. It's not the weather, gas or barrel or paint. I've also replaced the rear hammer oring without improvement. I've also bought the Madmann Spring Kit and put in the heaviest spring and actually lost a few FPS.
So... either the valve is crappy (although it's new straight from Tippmann) or my bolt(s) are getting hung up on the receiver. The rear bolt is scraping the left receiver half pretty badly, leaving scored gouges above and below the cocking slot. Could the hammer be striking the valve too weakly because of this? Tippmann says this kind of scoring and scratching is normal.
I'm running HPA at 850 psi now and still only getting 280 FPS (which is fine, but that's wasting a lot of air to get that velocity at such a high pressure).
Any ideas what to do?
Avery