American Air Arms rifles not serviceable by owners ?

[Amer1can_Ak1ta]

AOA told me that they found the leak in the regulator and replaced the O-ring. The rifle had air in it when I got it back, shot it a few times then recharged it a little then shot some more and added some more air but not filling to max. I noticed the air pressure gauge dropping a little, but so minor that you'd think you're mind was playing tricks on you if you didn't take pictures or mark the gauge where pressure is to see pressure drop. Days later, I filled up to highest pressure since getting the gun back (3700 psi). 30 minutes later, I hear a gushing of air coming from regulator area where air tube meets the receiver. I have to send it back again for repairs. I now think that this is a common problem for these guns. Maybe the air cylinder is flexing just at this end of the cylinder (since the end parts of the cylinder would be the weakest in my estimate) enough to allow the o-ring not to seal completely, especially under higher pressures. This area of the gun has to be the weakest link in the gun as far as air pressures are concerned. I also heard a little pop when the gun starts filling with air, just like last time it leaked.

 

[tommyt53]

My gun has always popped when it begins filling from my tank. I was also told by someone on here that you could fill the gun to 4200 with no problem. The first time I tried it the seal blew. Ive tried to call Tom at AAA to ask him about max fill but he never returns my calls. An owners manual would be a nice touch given the price of the gun.

 

[Amer1can_Ak1ta]

I guess it's normal for some guns to pop when filling. This pop just seemed louder than what I've heard before. I heard before on my other guns (Hatsan BT65). Two of them had a much smaller pop (probably due to much lower pressures) when I was filling them from my air tank and both of them started leaking probably because they were filling up too fast. Once I learned to control to fill them slower, I didn't hear the pop anymore. I now fill up with Yong Heng and GX CS2 portable compressors (as I returned the tank and hoping to get one with output/refill control) and don't have that problem. If I get the gun back with another leaking problem, I'll ask for a replacement gun or MAYBE a refund. It also seems that Tom is very busy so I don't know how long replacement parts will take if I have to keep sending it back.

 

[panahunter]

I replaced all o-rings on the gun and everything went well…pretty easy job. The old o-rings were in horrible shape. The spacer on the regulator gauge seems to be a bad design. That’s why I was intrigued to read that there’s a revised version. I hope I can buy a new gauge and spacer to resolve this. Seems to be the only issue with this gun. I love the way it’s put together otherwise….such a solid design. I emailed AOA to see if I can receive a new gauge and spacer. I’ll post back once I receive a response from them. 

 

[Amer1can_Ak1ta]

That's true for me too. I've never gotten a call back or email response from Tom about this gun or even just about ordering other items from their website. I've posted questions on their Q & A or something. I'm fairly new to airgunning but have been using my guns a lot and unfortunately, I've already gone into a little collection if you can call it that. After several leaking issues, I've learned that quality service after purchase is very important and something for me to consider for the future. I think no matter how busy an airgun maker is, he needs to devote some time or assign someone else to devote some time for customers after the purchase. Sorry, but I guess that is another subject.

Tommyt53, so I'm assuming your gun doesn't leak anymore?

 

[tommyt53]

Tommyt53, so I'm assuming your gun doesn't leak anymore?

Its to early to tell. I just received it back the other day and used it once and topped it off at 4000psi so far so good.

 

[slayer]

I'd like to address the reservoir tube o-ring and the gauge spacer o-ring.

Reservoir tube. 

O-ring design was based on the tube tolerances we were receiving at the time, as time goes on we have seen a change in the internal dimension of the tubing. The tubing meets specifications but the +0.002" change has created havoc on our original o-rings causing them to extrude through the larger annular gap. Generally, this extrusion doesn't happen immediately, it happens after a variable amount of fill cycles.

All guns manufactured after September of 2021 have our new 90 durometer Viton o-rings installed. These o-rings solve the extrusion issue and seem to be working well. They have been tested to pressures well over 4500psi. We have also cycled tested from 1000 to 4500 psi with no failures. I am unaware of any reported failures with the new o-rings.

If you have a current issue with tube o-rings please contact AoA to have them replaced with the new ones also PM me too.



Gauge Spacers.

There are two types. Steel spacer with NPT gauges and aluminum spacer (purple) with our new 3/8-28 straight thread AAA custom gauges.

If you have a steel spacer they can leak when the bottom gauge face is not fully tight with the spacer, this happens when the tapered threads tighten in the taper before the spacer and its o-rings are fully compressed. To fix AoA can tap the thread slightly larger to allow proper seating or the spacer can be omitted and and a good teflon sealing tape like the Ninja 6mil can be used.

The steel spacer/npt gauge has now been replaced with our new proprietary gauge which uses straight thread and an o-ring on the gauge. 

Receivers can not be updated to the new system but the front gauge/fill block can.

You can PM me here or contact the AoA service department if you are still having problems regardless of when the gun was purchased or if you are not the original owner.



Tom 

 

[panahunter]

I'd like to address the reservoir tube o-ring and the gauge spacer o-ring.

Reservoir tube. 

O-ring design was based on the tube tolerances we were receiving at the time, as time goes on we have seen a change in the internal dimension of the tubing. The tubing meets specifications but the +0.002" change has created havoc on our original o-rings causing them to extrude through the larger annular gap. Generally, this extrusion doesn't happen immediately, it happens after a variable amount of fill cycles.

All guns manufactured after September of 2021 have our new 90 durometer Viton o-rings installed. These o-rings solve the extrusion issue and seem to be working well. They have been tested to pressures well over 4500psi. We have also cycled tested from 1000 to 4500 psi with no failures. I am unaware of any reported failures with the new o-rings.

If you have a current issue with tube o-rings please contact AoA to have them replaced with the new ones also PM me too.



Gauge Spacers.

There are two types. Steel spacer with NPT gauges and aluminum spacer (purple) with our new 3/8-28 straight thread AAA custom gauges.

If you have a steel spacer they can leak when the bottom gauge face is not fully tight with the spacer, this happens when the tapered threads tighten in the taper before the spacer and its o-rings are fully compressed. To fix AoA can tap the thread slightly larger to allow proper seating or the spacer can be omitted and and a good teflon sealing tape like the Ninja 6mil can be used.

The steel spacer/npt gauge has now been replaced with our new proprietary gauge which uses straight thread and an o-ring on the gauge. 

<img src="View attachment cGxlbnVt gauge.1638665672.JPG" />//www.w3.org/2000/svg%22%20viewBox=%220%200%20210%20140%22%3E%3C/svg%3E<img src="View attachment Z2F1Z2U= block new.1638665784.JPG" />//www.w3.org/2000/svg%22%20viewBox=%220%200%20210%20140%22%3E%3C/svg%3E

Receivers can not be updated to the new system but the front gauge/fill block can.

You can PM me here or contact the AoA service department if you are still having problems regardless of when the gun was purchased or if you are not the original owner.



Tom 

Thanks, this is exactly what I needed to know! Yesterday when I was trying to resolve the leak on the receiver gauge, I took the cylinder apart and was surprised to see the o-rings I replaced a month ago had expanded and I had to replace them again. Specifically the 117 buna 75 and the 122 buna 75 on the regulator. So, I need to install these same sizes only Viton 90 spec? 


I will purchase a new gauge, as I believe the one I have also leaks. I’ll then try to install with thicker orings, and if that doesn’t work I’ll use Teflon tape as suggested and eliminate the spacer. It’s a pity we can’t upgrade to the new gauge on the receiver. 

 

[mercado]

I wanted one in 308 .. I asked for all ready aviable longer tank .. obviously not free.. if you ask for more cheese at a burger joint..it will be extra $ because the burger joint don't get cheese for free..so I was expecting yes it will this much...but answer was nop guns come as is . Like I was asking something custom in a $200 gun .. enough for me to see I could purchase other things..I don't need it .. he doesn't need my $ either...we all good..

 

[Amer1can_Ak1ta]

Thank you for the information Slayer. This is very helpful. Very much appreciated.

 

[slayer]

Thank you for the information Slayer. This is very helpful. Very much appreciated.

You are welcome. If you need o-rings PM me.

 

[Amer1can_Ak1ta]

Sounds good, I will let you know when I need o-rings. Thank you.

 

[Amer1can_Ak1ta]

"The steel spacer/npt gauge has now been replaced with our new proprietary gauge which uses straight thread and an o-ring on the gauge." This new proprietary gauge, does it still require the use of the purple aluminum spacer?

 

[slayer]

Yes purple spacer is required on new receivers with the new gauges. We have had no reports of the new gauge/spacer combonation eaking.

 

[Amer1can_Ak1ta]

Does anyone have instructions on how to adjust the hammer spring tension on the Evol?

 

[Airgun-hobbyist]

Does anyone have instructions on how to adjust the hammer spring tension on the Evol?

First, loosen and slide down rubber butt stock from the Magpul stock. There is a screw behind there that is then removed to release the stock from the tube. Slide the stock back to allow the tube to be unscrewed from the Evol receiver. The spring adjuster can be seen and accessed from there for adjustment. Reverse the procedure to reassemble.

 

[Amer1can_Ak1ta]

Thank you very much. Is there a small screw that locks down the hst adjustment nut (like the one in a Hatsan BT65)? Thank you very much. Also, I just shot 23 shots before the rifle fell off the reg (.22) and velocity started dropping. I had AOA adjust the regulator pressure for me (from 2400 psi to about 1800-1900 psi). I also asked them to adjust the hst to match the regulator pressure. It seems to me that the hst was not adjusted at all or if it was, the tension is still pretty high on the hs. I think I should have gotten a few more shots out of the rifle. I filled up the air tube to about 3800 psi. What do you guys think? I have had very limited time with the EVOL HPS .22, so I'm still new to it. I didn't document the shot count before having the rifle reg pressure adjusted. But based on my estimate, I'm not really getting that many more shots after turning down the regulator. Which direction to turn the hst adjustment screw for adjustments (up or down)?

 

[Peskådot671]

To get to the HST, you need to remove 4 screws/bolts. 

1. Start by removing the 2 screws on the bottom of the picatinny rail with a 1/8" alan hex key and remove the whole pic rail.

2. Remove the ambidextrous safety with 2 1/8" hex keys.

3. Remove the 1/4" main bolt from the lower receiver. The lower receiver with attached buttstock can now be removed to get access to the HST.

4. Loosen the grub screw that secures the HST on the upper receiver. I believe it's also a 3/32" hex key.

You can now adjust the HST with a 3/8" hex key I believe. Clockwise (CW) to increase FPS and counterclockwise (CCW) to decrease FPS. I usually adjust mine in 1/4" increments at a time. Don't forget to tighten the grub screw when you're done. Hope this helps.

 

[Airgun-hobbyist]

Thank you very much. Is there a small screw that locks down the hst adjustment nut (like the one in a Hatsan BT65)? Thank you very much. Also, I just shot 23 shots before the rifle fell off the reg (.22) and velocity started dropping. I had AOA adjust the regulator pressure for me (from 2400 psi to about 1800-1900 psi). I also asked them to adjust the hst to match the regulator pressure. It seems to me that the hst was not adjusted at all or if it was, the tension is still pretty high on the hs. I think I should have gotten a few more shots out of the rifle. I filled up the air tube to about 3800 psi. What do you guys think? I have had very limited time with the EVOL HPS .22, so I'm still new to it. I didn't document the shot count before having the rifle reg pressure adjusted. But based on my estimate, I'm not really getting that many more shots after turning down the regulator. Which direction to turn the hst adjustment screw for adjustments (up or down)?

Yes, there is a grub screw. I left my grub screw loose to allow for easy adjustment to the hammer spring while tuning. A drop of Vibra-tite VC-3 on the threads of the adjuster keeps it from turning on it's own. Follow Peskador671's procedure for removing the whole stock as an assembly the first time that you disassemble. 

Turn the adjuster in, clockwise, to increase spring tension and more hammer strike/speed. Turn it out, counterclockwise, to decrease tension and speed.

 

[Peskådot671]

Following Airgun-hobbyist way of adjusting the HST is another way of doing it but you do have to loosen the grub screw first otherwise you'll damage the threads on the HST if it's too tight when you turn it. It will also allow a more stable platform to run shots through the chronograph while making adjustments without the stock attached. Here's a pic of the back of the receiver where you can gain access to the HST without the stock attached and without removing the lower receiver assembly and pic rail. Using a ball head hex key will allow easy adjustment if it's at an angle.