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Posted: 2/17/2024 12:21:51 AM EDT
[Last Edit: themao]
So I finally picked one up, and I went ahead and bought a second one as a back up. Thanks to my crackhead friends/enablers for forcing me to do this crazy stuff

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I put some magazines through it Wednesday with the gas set to 1.4.

What worked:
- Circle 10 Bulgarian waffle magazine with Golden Tiger 123 gr JHPs (this is the good stuff with sealed primers, etc).
- Magpul MOE with PPU brass cased ammo
- Tula ammo in the Magpul magazine

What did not work:
- Bulgarian and Serbian steel magazine with Tula ammo (this is the crappy cheap stuff with gray colored cases, no coating). Multiple FTFs, one double feed

What worked half the time:
- Bulgarian commercial polymer magazine with Tula (didn't work at first, but then it worked).

I am surprised there is not a larger bullet guide or feed ramp. Again, zero issues with Golden Tiger or PPU brass cased using Magpul MOE and Bulgarian Circle 10 magazines. I ran out of time to load some PPU or Norma into a steel magazine. I suspect it needs to be broken in, and my friends on M4carbine.net said as such (https://www.m4carbine.net/showthread.php?177140-Swiss-Arms-SG-553-R-). I shot 100 rounds total and had to leave. I won't get to the range again until the end of March due to work.

On another note, I had issues with a Swiss AR stock adapter. The typical USGI locking plate will not mate to the AR stock adapter indentation. The buffer tube fits well. I forgot to take pics, but I wonder if I need a non-standard locking end plate. When I get back to town, I will try to post pics. I will also order some different end plates with a more rounded, circular peg rather than oval

Anyhow, I took the gun apart and cleaned it after my range trip. I compared the receiver to my 551s. There is a hole at the bottom just before the chamber, like on my 551s. I guess this is for over pressured rounds (so it blows out down away from the shooter)?

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Note the barrel was marked 2019 but my receiver is 2021 (not shown). Kind of cool given the pandemic and how they have to batch things.

Here is the chamber. Compared to my 551, the feed ramp looks the same and is quite small. There is not much of anything between the feed ramp and the chamber, unlike the feed ramps on the M4 or an AK bullet guide. I’m just used to seeing large riveted bullet guides on my AKs. That’s all. I just think it didn’t like Tula:

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That’s the best picture I could take with my iPad. Moving on, look at the lower receiver. There is little lateral play with magazines. There is a large amount of forward and rearward play with the magazine however. This was a hard picture for me to take, but here is the Magpul MOE magazine resting naturally without any pressure on it:

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Now watch it when I use my finger to push the magazine forward in the lower receiver. It moves forward maybe 3 mm:

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I can do this with the steel magazines and commercial Bulgarian magazines. Not so much with the Circle 10 magazines though. I’m guessing this was by design? None of my AKs will do that. I also find that unless I add generous lube to the magazine latch, I do have to push the magazine forward slightly to get it to release easily. Very weird.

Once I SBR the other 553R I bought, I’ll take it to the flat range, shoot prone, and see if magazine pressure induces any malfunction. I’ll just have to stick to brass cased ammo or good quality steel cased ammo (lacquer coated, good stuff like Barnual manufactures).

Regardless, it’s nice little pistol. Needs a tax stamp.
Link Posted: 2/22/2024 11:18:56 PM EDT
Thanks for sharing, nice pics and writeup.  

Wouldn't you say the more likely explanation for failures was low powered ammo and not being fired from the shoulder?  I just filed papers for SBR my 553RP 7.62.  My expectations are it'll run anything.
Link Posted: 2/24/2024 6:07:34 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Vapor_Man:
Thanks for sharing, nice pics and writeup.  

Wouldn't you say the more likely explanation for failures was low powered ammo and not being fired from the shoulder?  I just filed papers for SBR my 553RP 7.62.  My expectations are it'll run anything.
View Quote

Finally a reply! lol!

It’s a possibility. I will see how the second gun behaves. The lower to magazine fit troubles me though. I will compare it with my second gun and then call JDI.
Link Posted: 3/29/2024 11:59:04 PM EDT
So I bought the second 553R. Put 120 rounds through it with a brace on it for stability. Zero issues. Shot mostly brass cased Norma or S&B. Also shot 20 rounds of Hornady SST 123 gr with zero issues. It likes Bulgarian Circle 10 and commercial polymer magazines, along with Magpul. Also ate Golden Tiger just fine.

The magazine can be moved forward and back, but this lower has no issues with releasing the magazine unlike my other one. I talked to Dave at JDI, and he is ordering parts for my affected lower. Unfortunately, I cannot send it to Switzerland for inspection. It's probably just the magazine release on my lower.

I am going to SBR the second 553R I bought. Need to know who to put for the manufacturer though. The question asks for the importer and/or manufacturer. I guess I should list both since both are listed on the side of the gun:

SAN Imports
Frisco, TX

Sig Sauer AG
Neuhausen am Rheinfall, Switzerland

Link Posted: 3/30/2024 12:15:21 AM EDT
[Last Edit: themao] [#4]
Pics from yesterday. I only had time to go to my indoor 25 yard range. On the left is the 553R pistol with a brace. On the right a 551 with a Swiss aluminum lower. Targets have 120 rounds each at 25 yards (553 left, 551 right). I had to slightly zero both for windage, not by much.  I will try to do real 100 yard accuracy testing later in the next month or so.

I am submitting a form 1. Had an OSS flash hider installed today at my gun smith. I won't get time to run it suppressed for another three weeks.  I will probably just use an AR stock adapter over a Swiss stock based on my experience using the brace and for 922R compliance. 1.5" high scope mount works great for this gun, but I will probably ditch the bulky Delta mount for something slimmer. The Steiner 1-4x is a nice set up for this gun's intended use < 200 yards.

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By the way, the Swiss adapter did not work with some of the AR end plates I tried. I had to use an Aero Precision back plate. The hole on the adapter is more round than oval, unlike many end plates. Very subtle nuance. Something I never appreciated. Anyhow, I staked the plate to the castle nut without an issue. It folds nicely with the brace, etc. Once I get a form 1 back, I'll probably go for an OD green stock and pistol grip. I have a B&T 553 handguard I need to install. Add a magpul magazine, OSS flash hider and Shooting Sight hammer + sear, I will be 922R compliant after I get my form 1 back.
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