P320 USW SBR project

some_kid6

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Got the first pieces finally.

  • Have an M18 on order for that sweet sweet premilled optic slide and 3 mags.
  • I'm probably going to get a 509T but it's kinda hard to swallow that price tag. I might wait for a non Ti version. I want the enclosed optic but the battery life on the ACRO is like 2 weeks. I'm not sure what Aimpoint was thinking with that.
  • I went with the M18 so I could put on a threaded barrel and have it be protected by the holster. The holster is made for the full size so there's enough room to keep the barrel shrouded. This is gonna be some sweet kit with my Ghost 45M
  • I'm planning on SBR-ing it once I get the serial number.
  • I'm surprised by the LOP. It's like 0.7" longer than the max for an MOE stock.
  • "It's smaller and thinner than I expected." -she
  • This is the only modern stocked pistol you can holster that I know of. I'm not sure what all lights I can fit but I'm gonna put a folding VFG on it. Anyone know of a folding foregrip that will fit with the stock closed? I'm not opposed to modifying one. I might be able to just mill/dremel a groove for the stock to fit into
  • I can take the stock off and it's magically a pistol again. Farrow tech makes a brace adapter for this but you've gotta chop the stock part off to fit it. It also makes it way bulkier.
  • I've still gotta buy a threaded barrel, adapter plate, optic, remove the loaded chamber indicator, remove the manual safety, and figure out a foregrip.
  • I'll post more pics here as I get more parts
  • There's a convenient place to engrave the frame on the rail. I'll probably just engrave that since once I take the FCG out it's no longer an SBR
 

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This will prob be your best bet on the 509T. There is usually a 10% off code for their site too.
 
Update 1:

Cabelas finally had the M18 actually in stock and not "in stock but not really so we'll cancel in a week". Got it for $611.31 after tax and picked it up yesterday. I've got a P320 safety lever pin and apex trigger bar kit w/ flat trigger (Part# 112-031) so I can get rid of this safety and bring the trigger weight down to something more modern. I'm spoiled by my P99 trigger!

The USW grip is definitely less comfortable than the stock grip though but it's serviceable. I wasn't sure about the color match up but I'm happy with the Reese's PB Cup theme.

Next I need a magazine release (for the USW), a threaded barrel (gotta remove the loaded chamber indicator but that's easy), approved form 1, and a red dot + plate. I haven't decided on the dot + plate yet. I've gotta get a plate with sights since that's how the optics plate on the M17/18 is designed. I'll lose the fancy metal night sights but that's what the red dot is for!
 

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Nice, I might have to look into one of these braces. I actually just picked up my M18 on Tuesday, and I went with the DPP since that’s the optic the military decided on (for some reason)
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Nice, I might have to look into one of these braces. I actually just picked up my M18 on Tuesday, and I went with the DPP since that’s the optic the military decided on (for some reason)

Nice! One thing to keep in mind is you'll have to modify the stock to make it into a brace. The USW is legally a stock so this would be an SBR. Farrowtech makes the adapter to convert it to a brace though and it's pretty cheap.
 
Best email ever. Submitted 8/5, Sent fingerprints over that weekend, arrived today

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Removed the safety with a SIG 320 safety lever pin and got a Apex Flat Forward Set Trigger Kit. I'm underwhelmed by the Apex trigger but I'm also comparing it to a PPQ and P99. Still need a dot, threaded barrel, and I'm thinking about that griffin cam lock kit for my Ghost

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Update, Silencerco threaded barrel and Griffin Cam Lok both came in. Just need a red dot and either a light or a small folding grip and I'll be done! The threaded barrel with the Cam Lok is just barely protected by the holster.

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what version of p99 is that?
looks like a factory threaded barrel
 
what version of p99 is that?
looks like a factory threaded barrel

AS model for that sweet sweet DA/SA/AS striker. I put a factory threaded PPQ barrel in it. It's been a great suppressor host so far!
 
AS model for that sweet sweet DA/SA/AS striker. I put a factory threaded PPQ barrel in it. It's been a great suppressor host so far!
nice. i only have a ppqm2 that's threaded for fun. my m1 is a "goes with me" gun and my AS is a nightstand gun. AS is pretty jealous.
 
Update, finally got to take it to the range.

Notes:
  • Took 1 mag unsuppressed to get running suppressed but was fine after that
  • Recoils way more than I expected. I got bruises from it. It's a lot more comfortable with the suppressor though. Way less recoil with it on. That tiny stock footprint doesn't help but that can't really be fixed.
  • it REALLY needs a red dot. It's possible to use the iron sights but it's like looking between a bunch of buildings. Sights do stay very stable with the stock as expected.
  • Handles really well, works just fine in pistol form
  • Have to use the front of the slide to manipulate it but that's not too big of a deal
  • Lots of smoke out of the rear where your face goes when suppressed with steel case ammo (who could've guessed). It had fresh lube on it though which might be related. It did chill a bit with the clouds after a mag or so
  • I think it would benefit from some more weight like a light or foregrip
  • 5/7 would recommend
  • Griffin cam lok stayed nice and snug but came off the barrel threads since I didn't take the time to install it properly. That's on me though. The piston stayed nice and tight on it's associated mount though. I'm planning on putting it on my other guns now. it's just so fast to install!


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Update, my 509t finally came in. Unfortunately only 1 company makes an adapter for this sight and gun combo and it's not really what I want. So I'm making my own! I've got my first draft done. Still have some features I want to add as well as pick a final material. I'm test fitting with PETG since that's what I've got on hand and I let quality suffer since it's just drafts currently.

Safariland is finally in the mail as well so I can try to make a proper holster for it.

Next tasks:

* Add a glue in strut on the bottom for some more side to side security and initial alignment
* find my LCI and fit that so I don't cover my optic with carbon as soon as I shoot it
* Decide between a hard TPU, PETG/PC blend, sending to get milled, or sending to get a sintered print. I thought about investment casting it but that seems like a lot of work.
* Design some variants with integrated sights and a lower mount option for sadists that hate their cheekbone
* Maybe clean up the extra rail in the front so it looks cleaner
* test it some place with grass and a face shield
* fit a safariland to it
* share the STL, SLDPRT, and STEP files with the world!

Discoveries so far:

* Expansion/contraction is irritating on small parts
* there's almost no information on the technical drawings for this optic or mount
* the screws are M4x0.7 thread on the Sig mounts
* current mount height is based on the rmr mount it came with and is just high enough that you don't have to press your cheek bone into the stock to aim. I'm betting this is going to be way more comfortable to shoot since it won't be smacking you in the face every shot
 

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Redesigned the plate to put the optic more flush with the slide, added contours to match the slide, moved optic to use an off the shelf M4 flat head screw, added front of optic "iron" sight, and redesigned the alignment tab to be 2 glue in posts. Went with PETG @ 99% infill. Test fired ~200 rounds and everything held up. Even the temporary clip on front sight stayed put. Next task is making the holster but that'll be a summer project due to fumes.
 

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