American Air Arms All Things EVOL

[Dairyboy]

Well my issue appears to be the burst disc. Maybe it’s gone bad. When I reassembled the reservoir, cocked it, and began to fill with air, I noticed a semi-slow leak coming from around the burst disc. It was already pretty tight. When I removed it, I could’ve see anything obviously wrong, but I haven’t dealt with a bad burst disc in an airgun before. I used a ⅜” socket to remove it. This still doesn’t explain the air rushing out of the barrel the last time I tried to fill the reservoir. Today I stood my Evol up on the but and bumped the but on the floor a couple of times before filling. No air out leaked out of the barrel after that.
View attachment 391440

I need to look at the schematics and find the thread pitch.
Any suggestions as far as burst disc brands and reputable websites to order from?

I just ordered a set of 2 off Amazon last night to have just in case. Were from Captain Oring. I think there all the same threads? Guess I'll find out eventually lol

Captain O-Ring HPA/CO2 1.8k / 3k / 5k / 7.5k Burst Disk - 2 Pack (Compressed Air Tank Paintball) [Bonus CO Microfiber Cloth] https://a.co/d/3dHWl2B

 

[Vetmx]

Here's Tom's response to said question. If you haven't removed the tube, you don't understand yet. Threads aren't like other airguns. You barely thread on and no wobble. Very tight tolerances.

View attachment 391497

That’s what I figured. Super tight thread tolerance. The second you expose bare aluminum threading off and on, it could cause seizing issues. Need a oring lube that has anti seizing properties. Thank you. Krytox makes a lot of lubes. What does he recommend?

 

[mackeral5]

That’s what I figured. Super tight thread tolerance. The second you expose bare aluminum threading off and on, it could cause seizing issues. Need a oring lube that has anti seizing properties. Thank you. Krytox makes a lot of lubes. What does he recommend?

Unsure of what tom recommends but I will comment that Krytox GPL 207 has a higher viscosity than GPL 205.

.GPL 207 is a thick grease and stays put. Works well for bellevilles in a regulator

IMO GPL 205 is the best lube for dynamic orings under pressure such as those in a balance chamber or a regulator piston. it is not as thick but not thin enough to run A big help in preventing first shot stiction with balanced valves.

Ultimox 226 a thick grease similar in viscosity to GPL 207

 

[Vetmx]

I have Ultimox 226 at work. We use it when rebuilding certain hydraulic components when thread galling is an issue, mainly buttress threads. I will use it on the EVOL if I ever have to take it apart. Glad I read all of this.

 

[Dairyboy]

As shown here he uses Ultimox 226. That's what I have now.

 

[Vetmx]

I would like to say I would have noticed a difference when or if I took my EVOL apart but it may have been on one of those days when I’m thinking three steps ahead of what I’m doing. I would have been fuming mad if I would have seized something. Especially if the info about the issue with these guns was out there and I missed it. Thanks again for the heads up. The Ultimox at work will mysteriously disappear and we’ll have to order some more.

 

[woogie_man]

I would advise against using silicone grease to lube threads, and so will Tom, as well as others. After seeing what it did to a fellow air gunners tube threads, I will be using ONLY what Tom recommends to lubricate anything on the gun.

Yeah don't do silicone...if you do Tom is more than happy to do the repair for you, but it isn't cheap. Use the lube that was suggested above, Ultimox.

Trust me...use only that

 

[Vetmx]

Yeah don't do silicone...if you do Tom is more than happy to do the repair for you, but it isn't cheap. Use the lube that was suggested above, Ultimox.

Trust me...use only that

Or just put in the classifieds. EVOL .22. LNIB. One tiny blemish on end cap. $2,453 and buyer pays shipping.

 

[woogie_man]

Or just put in the classifieds. EVOL .22. LNIB. One tiny blemish on end cap. $2,453 and buyer pays shipping.

Don't have the end cap or cylinder. Tom had to use his lathe to cut the cap out to see what happened. I got a new cylinder and end cap.

 

[Airgun-hobbyist]

Working on resealing my Evol. So far I found this on my gauge block. It’s a Buna Nitrile size 122 Duro 70 oring. Krytox is what Tom Costan (@slayer) has recommended that we use to lubricate o-rings in the Evol.
View attachment 391399

Here is how it looked coming off.
View attachment 391396

This o-ring on the reg could use changing but I didn’t order any of those sizes or types in my last o-ring order. I hope they hold up until my next order.
View attachment 391444

What do y’all use to lubricate the threads on the Evol?

To prevent the threads cutting the o-rings, install/push the regulator down into the air cylinder so the o-ring is just past the threads first. Then, thread on the air cylinder to the receiver, aligning the regulator as it starts into the plenum. When tight and everything is aligned, fill it with air to push the regulator in place within the receiver/plenum.

Here's my installation process, with some extra steps to keep the threads dry:

First, clean all the threads and surfaces, including the regulator grooves. Now, lightly lube the inner portions of the o-rings and/or the grooves and install them on the regulator. Then, with a dry towel, clean off all the lube on the outside of the o-rings and around the regulator body. (So lube doesn't get into the air cylinder threads.)

Second, on the clean receiver, lightly lube just inside of the receiver plenum area where the smaller o-ring will slide in on the beveled edge.

Third, lightly and carefully apply lube deep inside of the air cylinder just past where the threads end. I use my fingertip or a cotton swab and spin the cylinder to get it evenly around in there. (Again, I don't get any on the threads.)

Now for assembly: Push the clean, dry regulator down into the air cylinder untill the big o-ring is clear of all the threads and rests on the smooth freshly lubed cylinder.

Thread on the air cylinder to the receiver, ensuring that the regulator is centered and starts it's way in the receiver plenum area. When the cylinder is fully threaded on and aligned with everything, slowly fill with a little air. The air pressure will push the regulator into place in the receiver and the threads remain dry.

If air is escaping through the barrel port simply put your thumb over it and lightly tap the butt of the gun on the floor.

 

[Ezana4CE]

So after I had an issue with the old burst disk, I bought some new ones. Before purchasing I asked about the thread pitch and where specifically to purchase them. Below is the response I received.

So I ordered some Captain O-Ring branded burst disks that do not fit the same as the original burst disk. After installing there is still a couple of threads visible and this Evol is still leaking air from around the burst disk.

Here’s how they look side by side.

Anything look damaged to any of you all?

I have no clue what the problem is or how it could occur with the gun sitting up unused for some months. Anyone have an idea what may be going on here?

 

[madeintheuk]

So after I had an issue with the old burst disk, I bought some new ones. Before purchasing I asked about the thread pitch and where specifically to purchase them. Below is the response I received.
View attachment 394928
So I ordered some Captain O-Ring branded burst disks that do not fit the same as the original burst disk. After installing there is still a couple of threads visible and this Evol is still leaking air from around the burst disk.
View attachment 394929
Here’s how they look side by side.
View attachment 394931
Anything look damaged to any of you all?
View attachment 394938
View attachment 394933

I have no clue what the problem is or how it could occur with the gun sitting up unused for some months. Anyone have an idea what may be going on here?

I just installed a captain oring burst disc on my mini also. While it didn’t completely fix my leak, It slowed down substantially. If it’s still leaking, I’m gonna be pissed. Nothing on it looked inferior to the old one other than the ugly chrome finish. Lol

 

[EDventure]

I have no clue what the problem is or how it could occur with the gun sitting up unused for some months. Anyone have an idea what may be going on here?

I've had paintball tanks blow in my car from getting hot. I assume that doesn't apply if you have them stored inside.

 

[Ezana4CE]

I've had paintball tanks blow in my car from getting hot. I assume that doesn't apply if you have them stored inside.

@EDventure Niether disk appears to have blown out. The leak is coming from around the threads. The gun has been stowed in the a/c with the exception of 5 days we were without power due to a storm. Outside temps weren’t into the 100s yet. From what I can recall, inside temps peaked around 86-89F during that time. I also don’t usually fill this gun to 4500 psi, let alone store it with that much pressure in the reservoir. I’m stumped here.

 

[Airgun-hobbyist]

Anything look damaged to any of you all?
View attachment 394938


... Anyone have an idea what may be going on here?

The bottom/floor of the hole looks dirty or damaged. This is where all the sealing takes place. I does not take much of a gap for high pressure air to push corrosion into these tight spots at the slightest bit of leak, which then become a bigger leak as more corrosion and dirt take tolls. It would be ideal to get is cleaned to the anodized or new smooth metal. A cotton swab and acetone should do the trick to clean it up If there is damage to the metal, I've fixed leaks with bit of metal polishing compound to smooth out grooves. To fix a lot of damage would require to send it in to be machined smooth again.

 

[madeintheuk]

That dirt in the photo could also be leftover tarnish from the brass seal. I’m not seeing any leaks from mine after installing the new one. I did snug it pretty good. Wasn’t sure if the new brass seal needed compression or not, but I did it anyway. Didn’t feel much “movement” to it when I tightened it up. Fingers crossed.

 

[Dairyboy]

I would make sure it's tight. But I havent removed mine to check and see if they work. They should?

 

[Vetmx]

If you already installed this one and took it back out for photos, you didn’t make it tight enough. Like I said before, a burst disc seals using its face. They have to be tightened enough to crush that brass gasket.

 

[Vetmx]

My EVOL doesn’t have a burst disc thank god.

 

[Ezana4CE]

I

I would make sure it's tight. But I havent removed mine to check and see if they work. They should?

@Dairyboy This concerns me because it was in there pretty tight. I don’t want to strip anything here. Are you turning your ratchet until the burst disc won’t turn any further or what?