Top Dead Centre Mod v. Action Army Hop Up Chamber
 

For those with sniper upgrade experience,

Does anyone know if their are greater benefits to the TDC mod over the action Army Hop Up chamber?

Better yet: TDC on an action army chamber

I used the stock chamber on my M24 with the TDC mod. Worked like a charm!
After doing that and getting great results decided to save my cash and run the stock chamber. I did have to shim it slightly as it the arm was off center.

would that work well? the AA chamber looks like the pdi one where the arms are lifted from setscrews in the bottom and tenssion comes from o rings. the TDC would work beter with a stock or laylax unit i think.
i guess if you could put springs under the arms above the set screws and then add 2 smaller TDC mods you could still use the two arm adjustability if the pdi style chamber.

Would that really work? I hope so.

I believe the AA Hop Up chamber actually botttoms out at some point. In the photo, you can see where the arm extends past the nub holder. I feel like the arm would reach a ledge, rendering a TDC useless. Just my thought.

Same issue would arise from a stock chamber too. It will bottom out the arm with too much travel. A taller nub will compensate if you're not having enough travel.

I've got myself a pdi clone chamber for l96 that I'm working on installing in my javelin m24 (snow wolf rebrand) and I already had tdc done on stock chamber. So I made a new single arm from some key stock and I'll have a spring lifting the arm up, while tdc screw applies pressure/positioning down. I just need to remake my sleeve to bush the hop chamber to the outer barrel.

TDC will work wonderfully on the AA chamber. But it also works wonderfully on the stock chamber, so you might as well save some cash and use the stock chamber. Simply put, it doesn't really matter which chamber you use for a TDC, so you might as well use the cheapest option.

I like how you think!

On a side note, I think the dangerwerx Hop up arm is stronger than the AA arm. The TDC mod would apply pressure with less flex in the arm if that's true

I wouldn't worry about that, these arms are all strong enough, you could TDC with the stock plastic arm and it would work fine. If you plant to use an r-hop, don't forget that you will need a flat arm with an m-nub or an arm that can use a large nub such as the prometheus. You could also make do with the male leaf arm.

I double checked my chamber today, I don't think it would bottom out the same way an AA would. I attached a picture that shows the arm could travel freely as far as the bucking and bb will allow.

Yet again, the stock chamber is the best. The others are just gimmicks anyway.

Would the dangerwerx arm not be enough? its a strengthened version of the stock arm, but you can buy them with a flat bar or two-prong nub

Depends, if you want to r-hop, ideally you remove the bump completely and use something like an m-nub. Otherwise, the flat bar arm is the best.

I do want to rhop the barrel. So I would ground the nub she off the stock VSR arm, and super glue an m nub to it? I'm confused.

Its a bit more complicated then that.

You also have to cut the m-nub so that it makes FLAT contact with the r-hop patch , since the arm is at an angle. You also might have to position the m-nub slight off center depending on your hop to get it to make straight contact depending on the tolerances of your hop-up unit.... all of which oyu can only figure out once you resembled it... so gluing and un-gluing...tons of fun.

Would you be able to give an example or explain it in another way?

I might have to position the m-nub off centre, off centre of what in particular? I'm not sure what you mean by the tolerance of my Hop Up unit.

Sorry, I'm new to doing this kind of work. I don't know anyone who can do it for me if I pay them

You have to adjust the m-nub relative to the angle of the arm. Depending on how much hop you apply, the arm will be at an angle of a few degrees compared to the rubber when you look at it in the "direction" of the barrel.

Then, the hop-up arm can move sideways inside the chamber. If you are using a Tokyo Marui chamber and a DangerWerx arm, chances are you will have a perfect fit and will not need to do anything here, but if you have, say, a JG or Well chamber, the hop-up lever arm will wiggle inside the chamber. You will have to shim it to remove that side play, then determine if the arm once shimmed is at the center of the hop-up rubber. If it is, good, put the m-nub in the center, if it sits more on one side than the other, you will have to move your m-nub accordingly.

Not only does a TDC work well on a PDI chamber, it's my current working configuration lol
The dual arms are totally useless, and I think they're REALLY only there to correct any issues you might have in not being able to align the barrel properly due to the crap design. So I've just got one bolt pressing on both arms.

Not sure why anyone's worried about bottoming out an arm. It's an Rhop. It doesn't have to go down very far to get full hopup, and even if it did somehow bottom out, just put a thick nub between the arm and hop rubber...

What Drakker is talking about with the Mnub is that your hop arm isn't pressing on it flat. It's pressing at an angle because it's so thick. Easier solution is to just make the Mnub shorter until the arm presses down on it pretty much flat.

The PDI chamber just absolutely is not designed for flat hops. Or convenient operation. Actually it really only serves to eliminate ONE issue (left/right hop bias) in an over-engineered and frankly, unnecessary manner.
If they're going to use O-rings, it needs to be higher tension and needs to be mounted right at the end of the arm for maximum tension.
Hop window needs to be longer and squared.
adjustment is just a huge pain in the ass and it needs to be TDC'd anyway so screw O-rings altogether.
and there's no positive alignment for the inner barrel. You just kind of eyeball it and lock it in place with set screws.

feedback note:

After receiving an AA hop up chamber in the mail today, the AA arm does not travel as far as the stock hop up arm does. While I have yet to test out the chamber with a TDC mod (or install a TDC mod on my Gspec), it seems as if the TDC mod would work better with a stock chamber. Results to come in the future.

The arm only has to travel about 1mm to get beyond the max range you'd need for a flat hop.
Just use a harder nub, and if you need the arm to sit higher, use a thicker nub.