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MagPul PTS MASADA ACR


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I have some calipers arriving this week, hopefully today, so I'll measure a few pistons for comparison.

 

Can you be more specific about how piston length was a problem? Too long and unable to fully cycle?

Finally I get to respond to your question. In addition to my comment about spring length :-

 

Systema (M120? M130? spring) cut. But acceptable length for the ACR mechbox seems to be 161mm (note taken from an angle that's why it looks longer than 161mm) :-

 

ACRSpringL.jpg

 

ACR original Piston length 66.56mm :-

 

ACROrigPistonL.jpg

 

Red Element Full Metal Teeth 66.98mm :-

 

ACRRedPistonL.jpg

 

Sharp Shooter single metal tooth 67.11mm :-

 

ACRShShPistonL.jpg

 

So even the Red Element which works as a drop-in is not too far off from the Sharp Shooter (i.e. the Red Element must really be on the borderline whereas the original ACR clear is "clearly" (no pun intended :-)) being generous. Now of course one may say that the spring I'm using already is too long that it's preventing the piston from compressing however (you'll have to take my word for it that) I've used the same spring in other V2 mechboxes with a clear Sharp Shooter with no problems. So at least in my experience, the ACR Mechbox still not as tolerant as a standard V2 mechbox.

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Yours definitely had wobble. And it has since been fixed. Who else's has been confirmed to have wobble? Because out of the 3000 units sold so far, yours is the only one that I'm aware of that has been

I like how me pointing out the obvious in my last post has garnered a negative rep. LOL. Haters gonna hate.

I Lol'd at all the fanboys who had to have this must have aeg. To be honest it seems as if youy have all been taken for a ride. My A&K Masada with systema gearbox *suitcases* all over this ares ab

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Back to the tech topic though, no one seems to have talked about the spring length. These are also a contributors to lockups. Unfortunately I have yanked all my springs out of their packaging and don't know what's what brand anymore. In addition I tend to buy strong springs and cut them to get as close to 0.98J. I can go home and measure my spring length later tonight.

 

A friend of mine has an Angel 0.9J of which is borderline on spring length - it works only if the installation of spring guide is completely flush to the mechbox (as it should be). If it's slightly tilted, he gets lock-ups - even with PTS stock clear piston.

 

I've had a 100, 110, and 120 springs in mine without a problem. Sorry, don't know the Joule measurements off the top of my head. I didn't think the spring guide nut would go in all the way without aligning the spring guide to be flush though to be honest, I never really tried.

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As for spring length, a Madbull 120 is to long, so is was the System 120, and the Modify 120.

I am beginning to wonder if the stock spring is already cut down or if they are using a "custom" spring to better response time?

 

Did you take that weight/spacer out of the piston? I'm using pretty standard stuff here once the spacer is removed.

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No, just swapped out the stock spring for a different spring.

 

The stock spring was about 3/4" shorter than a normal spring. The spacer will push a spring "back" about 1/2" inside the piston so a standard spring could be almost 1" - 1 1/2" compressed before the piston is even pulled back. Might account for the binding you and others might be seeing.

 

Disclaimer: These are estimated measurements as I don't have the stock spring or spacer in front of me right now. I'll try to update later when I can get a pair of calipers on them.

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Doubt it, I don't see why he would for such a build.

Well, changing to bushings is much easier than sanding down axles. I can't recall if I changed my bushings or if I used the standard ACR PTS ones however I did not experience any tightness or binding between RiotSC's gears and the bushings I'm using now. Got it shimmed pretty well too.

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Now I just THINK you're trying to get on my nerves and make me repeat myself so that you can bash me again, therefore you may answer your own questions.

 

I'm sorry if you got that impression. All I've been trying to do is clarify what you've been telling us. We are all trying to get the best out of our Masadas, so we need accurate information.

 

For the gears, he sanded a -little- bit of the gear axles as they were incredibly tight with the bushings.

 

Aaaah ok. That's interesting, because my stock bushings worked fine with those gears. However, in the past I received a Siegetek bevel gear with an axle that was slightly too thick to fit into any bushing. Apparently there can be imperfections in the coating process. RiotSC is very good about replacing faulty gears though, so manufacturing defects aren't a concern. Other users have reported no problems with Siegetek gears and stock bushings, so yours might be another case of slight manufacturing imperfection from Ares, Siegetek or both.

 

Now of course one may say that the spring I'm using already is too long that it's preventing the piston from compressing however (you'll have to take my word for it that) I've used the same spring in other V2 mechboxes with a clear Sharp Shooter with no problems.

 

Sorry, it's been a while and I don't remember what problems you were experiencing. Are you saying you've had gearbox lockups with certain spring/piston combinations?

 

Nobody has mentioned solid spring length, which is the only measurement you need to think about if you're concerned about spring length causing lockups. Extended spring length tells us little, because different springs are made with different wire thickness. You have to accurately measure the wire diameter, then multiply that by the number of coils to get the solid spring length. Then put your piston of choice into the gearbox along with the sector gear and spring guide. Move the piston to the release position, then measure the distance between the spring guide base and the front inside wall of the piston.

 

There's plenty of room for the PDI and Guarder springs I've tried (PD1 120/130, Guarder 110-130), but of course I wasn't using the ridiculous weight that came with the stock piston.

 

Ah I C...ok so it's not necessarily the the gear axles itself then. Did he try other bushings?

 

Doubt it, I don't see why he would for such a build.

 

Why on earth would an airsoft tech try other bushings if the ones he's using seem too tight?

 

Sarcasm over, RiotSC told me the only 8mm bushings you should use with his gears are Modify 8mm tempered stainless steel. His gears are so hard that over time they will wear down softer bushings, so I would regularly inspect the bushing holes to make sure you're not about to destroy something in there.

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Sorry, it's been a while and I don't remember what problems you were experiencing. Are you saying you've had gearbox lockups with certain spring/piston combinations?

 

Nobody has mentioned solid spring length, which is the only measurement you need to think about if you're concerned about spring length causing lockups. Extended spring length tells us little, because different springs are made with different wire thickness. You have to accurately measure the wire diameter, then multiply that by the number of coils to get the solid spring length. Then put your piston of choice into the gearbox along with the sector gear and spring guide. Move the piston to the release position, then measure the distance between the spring guide base and the front inside wall of the piston.

 

There's plenty of room for the PDI and Guarder springs I've tried (PD1 120/130, Guarder 110-130), but of course I wasn't using the ridiculous weight that came with the stock piston.

Oh I wasn't having any problems (or any problems I had I've solved them myself - then reported here back in Dec '10 - finally responded to your old question back then too about piston lengths).

 

Digging back a little history, my friend did experience lockups as the spring he bought was just too long, and he also misaligned the spring guide during installation. I just remembered it recently in the past few days and thought it worthy mentioning on this forum as something ACR modders need to watch out for.

 

To me with respect to the ACR mechbox, aside from the infamous micro trigger & its associated semi auto-cutoff trolley design, the other part is the length between the base of the spring guide to the cylinder head. That portion seems to leave little room for play as such the piston length, and the spring length used with it requires a delicate balance during installation. At least in my experience, this is the part that's the source of upper mechbox lockups.

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What Model should I get? The A&K Model or the Magpul PTS?

 

I can't vouch for the A&K version.

 

I personally like the Magpul version thus my choice when buying. I think you'll have to do more research and figure that one out on your own unless there are those here who have owned/played with both for some period of time.

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Has anyone had issues with using MAG brand magazines?

 

 

 

I did. My MAG 130's did not lock in at all. I had to gently remove a small bit of plastic from the catch area to get them to work. They also had some feeding issues, but my mags were old. I just started buying PMAGS to replace them. I now have 14 PMAGS for my loadout.

 

Crash

 

 

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I own a PTS but I've also held an A&K. To -me- the PTS feels more solid & robust in the hands...it just feels better.

 

On the other hand in terms of upgrading, A&K seems to conform to V2 specs. As you've read about the PTS version, it leaves little room for specs discrepancy.

 

As for use, though it may be a double-edge sword, I do like the micro trigger, almost a hair trigger. Having said that, I don't know if anyone has tried installing the AWS Stealth/Raptor into the A&K version to get the same feel.

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It might be in these 101 pages, but wanted to ask this morning - the trigger assembly on mine just went. The tech needs to get a new ARES geabox for the fix. Just wondering if there are any other options? Or anyone swap the GB for another type?

 

Thoughts?

 

Thanks

Eric

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