[Nny999]

Hello, I'm Nny, Sorry to write here, and I don't want to bother anybody, but I ran into an issue that I don't know how to fix, hopefully somebody here will be able to help me. Here is my current situation:

After some consideration I wanted to play the sniper role on some of the fields I play on(For the rest I still have my AEG HK416)
So I though as a fun little airsoft winter project, I would purchase a sniper and slowly build it, upgrading/modifying as I went along.

I did some research(honestly not enough of it), selected the AAC T11, It was VSR fully compatible, I liked the looks, the trigger was a 90 degree one, and everything else I would just upgrade. Seemed like a solid choice

Mine came with a plastic spring guide and a plastic piston with a 250 fps(0.25bb) spring, so that needed to go.
I bought a full replacement kit for VSRs together with a m170 spring(Field limit is 550 fps)

Unfortunately when I tried installing it, the Spring was much longer then what my barrel allowed, I tried inserting it with force and managed to close it, but the spring inside was under so much tension, I couldn't pull back the bolt and I'm by no means a small guy. I tried cutting the spring, but had to shorten it by a fair bit to fit it inside without much tension. I could then pull the bolt back to the end, but the trigger wasn't catching it(at all, it just slid back)

So I though maybe the piston is incompatible with my trigger, but when I tried the weak 250 fps spring that came with the gun with the new parts, the trigger stopped the spring just fine, so the 90 degree trigger was compatible with the new piston.

I though maybe the spring was just not compatible with this gun since it was much longer originally and I must have cut it up too much.
So I bought a AAC M170 Spring that length wise should fit in just fine, together with a Action Army Hop up(The famous red one).

When installed, I ran into an issue that when the bolt is pulled back, the trigger stops it, but only for some force. If I pullback the bolt and then hold the handle with like 30-40% of the force needed to pull it back, it holds it, but if I dont hold it at all, it fires by itself without pushing the trigger. I can feel the 90 degree trigger holding it, but its like it gives out if the full force is applied to it.

I though maybe the piston is too far away from the trigger and it isn't holding it properly so I made a improvised SorboPad and inserted it inside. Same situation, the trigger caught the piston a bit sooner, but it still gave out. So the measurements length wise seemed fine. Maybe the height? I just don't know. Is it the trigger or the piston at fault? Is the trigger not strong enough to hold a m170? Are my piston/trigger not compatible with each other?

I would appreciate any help because I'm at a loss, I don't want to order parts one after another but still not fix the problem. I can provide additional pictures/video of the problem and other parts if somebody needs it.

Thank you in advance.

 

[Akami]

Try to put a washer on your trigger to receiver connection. A sheet of aluminium can should be enough, just don't add it too much.

Or try to assembke the cylinder without the spring, and see what's the probem.

 

[Plazmaburn]

Are you 100% sure its a 90 degree trigger? I thought the T11 came with a 45...

 

[Akami]

AAC T11 indeed came with 90°, though it isn't tough steel but it easily hold m130

 

[Nny999]

Upon further inspection the piston is indeed a bit loose, I feel like if the trigger pushes hard enough, the piston will slip since there is about 1mm-1.5mm of room to move it, Im going to try to add a bit of aluminium in the back of the piston, since that part should normally not move at all, I think I can just wedge it in there and it should be fine. I'll add it to the back of the cylinder, behind the piston, on the wall, so it pushes the piston more towards me. Should be fine right?

 

[Akami]

I wouldn't give any material to places where it could interrupt the mechanical movement or it could result in fatal failure, at least to the parts that I'm not sure yet it is the problem.

I once having this problem too where the sear won't catch the piston or it would catch but slips and then fire. It turns out that my sear is too high that it can't return to 90° position, in order to get locked by the second sear and catch the piston. So I lowered the sear, by adding aluminium sheet to act as a washer between the receiver and the trigger box.

 

[Nny999]

Its the opposite problem, the sear is too low to catch the piston, I added a folded aluminium sheet to the back of the cylinder, so the piston will be higher up, and the sear caught it with no issue. I guess a new piston of higher quality might solve it, or I just find a way to increase the height of the sear

 

[Akami]

I see. You have Airsoftpro piston, right? It is either your sear has weared off or the piston is indeed smaller than the inner diameter of the cylinder.

 

[Nny999]

This Piston should be fine no? Its also an action army so its the highest chance of fitting in, the rest are little things to improve the rifle, also m170 is way too strong and my hand hurt after about 20-30 pulls, I think a 150 should be better

 

[RonSwanson]

View attachment 21588
This Piston should be fine no? Its also an action army so its the highest chance of fitting in, the rest are little things to improve the rifle, also m170 is way too strong and my hand hurt after about 20-30 pulls, I think a 150 should be better

Careful with the spring power, I believe the stock trigger us rated up to m130 anything above my at wear quicker and cause it to fail and need replacing sooner.