casing issue - possible stripped thread?

[billdz]

I flew a rocket Saturday with an AT reload in a 29/40-120 casing. I cleaned the casing after the launch and today was going to put it away with the closures attached. However, when attaching the closures, on both sides I encountered resistance after a few turns. Tried the closures on another casing and they went in fine, so the issue must be with the casing. I checked for grime on the threads but did not see anything. I sprayed some WD-40 but that did not seem to help. I have not tried turning the closures more forcefully, as that would probably make it worse. I've used this casing 2 or 3 times and there was never a problem before now. As instructed, I greased the threads before loading the reload. I was able to unscrew the closures for cleaning with no problem.

So what does this mean, are my threads stripped and the casing is now garbage? How could this have happened to the threads on both sides of the casing on one launch?

 

[ksaves2]

I flew a rocket Saturday with an AT reload in a 29/40-120 casing. I cleaned the casing after the launch and today was going to put it away with the closures attached. However, when attaching the closures, on both sides I encountered resistance after a few turns. Tried the closures on another casing and they went in fine, so the issue must be with the casing. I checked for grime on the threads but did not see anything. I sprayed some WD-40 but that did not seem to help. I have not tried turning the closures more forcefully, as that would probably make it worse. I've used this casing 2 or 3 times and there was never a problem before now. As instructed, I greased the threads before loading the reload. I was able to unscrew the closures for cleaning with no problem.

So what does this mean, are my threads stripped and the casing is now garbage? How could this have happened to the threads on both sides of the casing on one launch?

You'll find out the next time you use the case. If the threads are stripped, when the motor is fired the aft closure will blow off. Happened to me with a 2 grain 38mm AT case that
was well used for research load testing.

Was a funny flight as the rocket had a MAD deployment unit so when the button was pushed, aft closure blew off and the rocket went up 4 feet on the 6 foot rail and came back down.
A spring clip was used for retention so the closure blew by it. Won "closest to pad" award that day. Rocket is fine and I still fly it to this day.
The grains were only lightly scorched so I flew 'em in another case later and they worked great. Kurt

 

[fyrwrxz]

Billdz-Mike the case dia with a known good one. See if the case got overpressurized and deformed the threads.You can usually see a slight bulge in good light looking axially. Also try another closure.

 

[grouch]

Is the case still perfectly round or is it slight oval?

 

[billdz]

Looks perfectly round as far as I can tell. I decided to apply some additional force and it worked, at least I was able to screw the closure fully in. Still no idea how it could have gotten stripped or deformed.

 

[blackjack2564]

Crud in the threads, it doesn't take hardly any.