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Discussion Starter #1
I am thinking about putting together a PS90 from parts using an Effen90 receiver. I do already have a SBR'd PS90 that I love, and understand how the rifle works. However I have a few questions/concerns.
Parts I already have. Green stock, trigger pack, end plate, flash hider,
Parts I need to order. Effen90 receiver, barrel (once my form is back), cocking handle, cocking handle spring, barrel lock, barrel lock spring, barrel return spring, and the moving parts assembly.
MGW has everything except the barrel return spring(HDD has them), but they offer two versions of the moving parts assembly.

I always thought that the full auto bolt assembly was the same as the semi auto version. Is there a reason to get one over the other? Is there a difference?

Those of you that have seen the Effen 90 receivers, it looks like you can remove the side rails since they are held on with screws, can you confirm this?

Are there directions anywhere on how to put the receiver together? When I removed my barrel last time I followed it out with a dowel. I was told it was really hard to get it all lined up otherwise. I have seen a parts diagram, but is there a tutorial posted anywhere?

Any parts I missed?

Anything else I missed?

Any reason not to put one together this way? It probably isn't saving any money, but I already had the stock and trigger pack, and PS90's aren't in any of my local shops.

Thank you,
 

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I am doing the exact same thing you are doing, and am at about the exact same spot in the process. It think if you bought all of the components directly from a retailer it would NOT save you any money at all. I think I will probably come in just under the cost of a new Standard PS90 and that is with lucky major breaks I’ve gotten on some parts and from very helpful members here giving me great deals.
I would say that the wing rails on the Effen could be removed but I wouldnt go taking them on and off again too many times since it is aluminum and the mounting screws will be steel or something much harder than aluminum. Aluminum threads dont hold up too well over time if you keep doing that.
Other than that, its probably pretty logical to put back together, or to put a new one together usig the Effen receiver. Do you still have your manual from your current PS90? It might say in there.
 

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Discussion Starter #4
I do have the manual, but it is no armorers manual, just shows basic takedown. I looked at a copy of the armorers manual online, and it has a good blown up diagram showing where everything goes, but is not super clear about what order you put the parts in. It looks like you would put the charging handle in first, then it's spring, then the button and it's spring, then feed the barrel through carefully and put on the flash hider and it's spring. I'm sure it is pretty intuitive, but sometimes there are a few tricks that make the process a lot easier. I have assembled tons of other rifles and there are lots of little tricks for pushing pins, lining up gas blocks and the like that I wish I had learned earlier. I would like to figure those out before I try to assemble it rather than after. :D

I want to order it with the rails and then remove the one on the left side while keeping the right one for a light mount. I made a laser mount already that will mount to the polymer, so don't need the other side rail.

Any insight on the difference in the moving parts groups? They look identical...
 

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Discussion Starter #5
Cost is excessive. Sell the parts, buy a PS90 standard, sell the receiver and get the Effen receiver.

I built my SBR with parts and even with all the deals I got, it still cost way more than I wanted it to, and way more than if I would have just bought a new rifle and started there.
I've checked all the shops near me and none of them have any in stock. One offered to order me one but wanted more than MSRP for a used one. I looked at grabagun, buds, sportsmans warehouse, etc... nobody has any.

Do you know if there is any difference in the moving parts groups offered by MGW?
 

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Discussion Starter #9
Thank you both, I will have to think about that and do the math. As I said above, I already have the stock, trigger pack, and end plate. I do also have the longer barrel from my other PS90 that I could have cut down to save a few bucks over buying a new one.
 

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As far as I can tell the moving parts groups are exactly the same. The weight doesn't even seem to be different. Others (fully licensed) have converted PS90's to select fire and haven't had to change it out. If you want a copy of the armorer's manual hit me up with a PM and I can email it to you.
 

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So I did an Effen90 SBR build, it was about $150 more using a used bolt carrier. Here was my analysis: The stock was sending the barrel to the vendor on the forum everyone uses.

Effen90Stock
Effen90 Rec.399374+25 transfer1325
Stock and Butt290FN Forum
Bolt/Charging Handle and Spring455Used GB
Trigger Pack179MWG
Man Kave Hammer7575
Springs/Rod48MWG
Barrel260192
CMMG Thread Adapter34
17401592
Tax Stamp200200
Tax Stamp Service5050
Engrave5050
20401892
 

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Discussion Starter #12
So I did an Effen90 SBR build, it was about $150 more using a used bolt carrier. Here was my analysis: The stock was sending the barrel to the vendor on the forum everyone uses.

Effen90Stock
Effen90 Rec.399374+25 transfer1325
Stock and Butt290FN Forum
Bolt/Charging Handle and Spring455Used GB
Trigger Pack179MWG
Man Kave Hammer7575
Springs/Rod48MWG
Barrel260192
CMMG Thread Adapter34
17401592
Tax Stamp200200
Tax Stamp Service5050
Engrave5050
20401892
Thanks for the really good breakdown. Since I already have a lot of the parts and don't want to sell those, I am going to piece one together too. I just ordered the rest of the parts except the moving parts group. Hopefully my LGS gets the receiver in a few days and I can mail in my form 1 by Friday. Then I get to wait. No rush getting the moving parts group since it will be about 6 months. I have time to look around. If not MGW has them too.

Thank you all!

View attachment 124777

This is a pic of my current PS90
 

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Thanks for the really good breakdown. Since I already have a lot of the parts and don't want to sell those, I am going to piece one together too. I just ordered the rest of the parts except the moving parts group. Hopefully my LGS gets the receiver in a few days and I can mail in my form 1 by Friday. Then I get to wait. No rush getting the moving parts group since it will be about 6 months. I have time to look around. If not MGW has them too.

Thank you all!

View attachment 124777

This is a pic of my current PS90

No worries... but considering getting the moving parts group while its available, as things go out of stock for long periods of time because of the niche market for the ps90...
 

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Discussion Starter #14
Progress so far. I did call and talk to FN about the moving parts group and they told me the parts were the same, so I ordered the semi auto one just in case they sell out. I also mailed in my Form 1 last Wednesday and got a notification from my bank that the ATF cashed the check this morning. I'm crossing my fingers that this one comes back sooner than 6 months. I'm still not sure which optic to go with, but hopefully there are some good sales before Christmas. Now the real wait begins.

View attachment 124929
 

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I just tried the new EFile system with the ATF on a couple of ps90's that I've been intending to shorten to their natural length. We will see how long it takes them to get back with me. I think a lot of people started putting requests in through the efile system this month. I am not sure, but think I will probably have TROS cut both of those barrels as it is 100 cheaper to use your own barrel. I took my Effen90 SBR our last week for the first time and it ran great. It was my first time to use my AAC 30 cal suppressor and it did a great job as well. Fun little guns.
 

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I also mailed in my Form 1 last Wednesday and got a notification from my bank that the ATF cashed the check this morning. I'm crossing my fingers that this one comes back sooner than 6 months. Now the real wait begins.
They always cash the check immediately, the current wait is running around 6 months.
 

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Discussion Starter #17
I took my Effen90 SBR our last week for the first time and it ran great. It was my first time to use my AAC 30 cal suppressor and it did a great job as well. Fun little guns.
Nice! I have a Energetic Armament NYX Mod2 that I put on my PS90 SBR and love it. I keep thinking about getting a 30 cal suppressor, but decided to build the new rifle instead.
 
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