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Discussion Starter #1
Well, looks like I was beat to the punch (with video no less) but I said I would post my impressions when I got my upper, so here it is.

I picked it up from my dealer today, conveniently the same dealer that has my Coharie MP5SD and suppressor while I'm waiting on the stamp (more on that later).

The fit and finish of the receiver looked great. The welds looked way better than some of my older Coharie/Special Weapons clones that I have and looked at least as good if not better than the Zenith gun I have seen. It came with a small black soft case, which while perfectly serviceable, won't fit the SD when fitted with a collapsible stock and suppressor (my guess it that it was sized more for an MP5 than an SD). It also came with a quality control checklist that had been hand validated and signed by the QA person.

While at the dealer, I tried both my fake SD can (I was told it was made by Coharie, but I bought it second-hand) and my actual Coharie SD suppressor. The fake can fit with no issues. The Coharie SD suppressor fit, though it was a tight fit and there was a little bit of rubbing, evident on the can and by looking inside the shroud (not a big to me, though).

When I got home, I used calipers to measure the ID of the suppressor shroud and found that it was 1.6485".

I pulled the bolt and it looked good, with an RCM marked bolt head. Both HK curved and straight mags, as well as curved Korean mags, fit in the mag well smoothly and locked into place with no issues. The mag release and paddle release both worked smoothly as well.

I put my registered sear/pack on it, in an HKparts purchased clipped and pinned SEF Navy type housing, along with a US made MP5 F A3 type collapsible stock (also HKParts). Both dropped into place with no issues and had a nice tight fit. The stock collapsed along the rails slots with no problems.

So, all in all, I'm very impressed with the gun and I look forward to getting it to the range (even if it will be a while before I can shoot it with a real suppressor, instead of the fake one).





















 

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Beowulf, thanks for the awesome review and pictures.
That Omega SD looks so much better than the previous Omega MP5 guns I've seen in person.
Very impressed... can't wait to get mine :)
 

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Nice pics and thanks for the review and info.

Where does your Coharie suppressor rub on the cage/handguard? Is it at the front of the cocking tube, where the ball detent of the cocking tube support engages it?
 

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My RCM can rubbed the cocking tube support, on the right side (looking down the sights) when the support was in the hold-open. Took a flat file and beveled that edge, so it wouldnt score my can when I screwed it on. Took all of 10 minutes. Might be worth rubber SD handguard off the cage, and looking in with a flashlight when you put the suppressor on?
 

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Is it pictured with the faux suppressor? and what does faux suppressor bring the barrel length to?
 

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Discussion Starter #7
Is it pictured with the faux suppressor? and what does faux suppressor bring the barrel length to?
That is with the faux suppressor. With it on, the barrel length is 5.75". :biggrin:

Now, if it were permanently attached, it would only take it to 12", so not long enough if you were thinking of making a non-SBR/suppressor version. However, you might be able to find a 16" faux suppressor out there that you could permanently affix.
 

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Discussion Starter #8 (Edited)
Nice pics and thanks for the review and info.

Where does your Coharie suppressor rub on the cage/handguard? Is it at the front of the cocking tube, where the ball detent of the cocking tube support engages it?
It actually appeared to rub further down the shroud, at least that's where the marks on both the can and the shroud were. Unfortunately I don't have the can in my possession yet, so I can't double check.
 

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Discussion Starter #11 (Edited)
Okay, time for a range update:

I took the barrel SD upper out to the range today, along with my Fleming sear pack and my Coharie fake SD can. I'm sad to report that it was jam city. At best, I was able to get 2 rounds in semi auto out of the gun before it jam or fail to eject.

Now, I'm not ready to blame this on the gun itself. I have a sneaking suspicion that my old Coharie fake can wasn't sealing the barrel ports enough, letting too much gas escape to properly cycle the gun. The recoil felt pretty subdued. I tried several types of ammunition, WWB 115gr, Tula 115gr, Midwest Ammunition 115gr (which is the house-brand if you will at Point Blank range in Indy). No go on any of them, but all of them cycled my Coharie MP5 SBR just fine.

So, has anyone else tried shooting theirs with a fake can and if so, what manufacturer of can? I know there are couple out there and since I'm looking at probably until November on the stamps for my other SD and suppressor, then a fake can is my only option at the moment.

Edit: I also just realized that I probably should have swapped the locking piece for a 100 degree one, since standard SD locking piece is 115. So, I might need to re-run my test with the proper locking piece in. The thing that really peeves me now that I remembered that is that I had my MP5 SBR with me and I could have just swapped it at the range. Oh well, live and learn. So, now I have 2 factors that I need to test before I can really narrow down the issue (well 3, if I could convince my 07/02 to come out the range and bring my Coharie suppressor, so I can try it with a proper can on it).
 

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If anything the gun should have run anyway with the SD locking piece in it because it unlocks faster and puts more energy and velocity into the bolt group due to its higher shoulder angle which usually does not impact ejection. Its usually an ammo issue. Make sure to try with some 124gr ammo.

I can't speak definitively to your fake can but try to eliminate the mag by shooting it as a single shot. Also eliminate the other usual suspects in FTE malfunctions I.e. make sure that the bcg is not dragging on the ejector lever and that the ejector lever does ride up high enough to reliably contact the spent case. It also should go without saying that extractor spring should also be checked to ensure its good.
 

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If anything the gun should have run anyway with the SD locking piece in it because it unlocks faster and puts more energy and velocity into the bolt group due to its higher shoulder angle which usually does not impact ejection. Its usually an ammo issue. Make sure to try with some 124gr ammo.
Help me understand this. I was to the belief that an LP for a suppressed rifle was intended to delay the opening of the bolt to allow pressure to fall before the bolt group moves, not open faster. The recent thread about the G3 beating up the back plate is confirmation that the wrong LP causes TOO much bolt velocity with a can. So how can the SD LP run better than a standard LP in a gun with no can?

I personally believe the OP diagnosed his own problem and is on the right track by installing his other LP. Because the can is missing, there is no extra pressure to operate the weapon and the bolt opens to late.
 

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Help me understand this. I was to the belief that an LP for a suppressed rifle was intended to delay the opening of the bolt to allow pressure to fall before the bolt group moves, not open faster. The recent thread about the G3 beating up the back plate is confirmation that the wrong LP causes TOO much bolt velocity with a can. So how can the SD LP run better than a standard LP in a gun with no can?

I personally believe the OP diagnosed his own problem and is on the right track by installing his other LP. Because the can is missing, there is no extra pressure to operate the weapon and the bolt opens to late.
What you say is true for non-ported barrels like those mentioned i.e. a G3 with a can using #17 LP (36 degree) or a suppressed mp5k with a can using a #28 LP (80 degree). The SD is an exception to this rule due to the porting in the barrel. This design effectively shortens the barrel from a suppressor standpoint in order to allow supersonic ammo to become subsonic when used in the SD.

The general concept for LP selection is the higher the locking piece angle used the faster the action unlocks and more energy is transferred to the bolt group not unlike pressing the accelerator on car to make it go faster. To help illustrate this with an example this is the exact reason why a 100 deg LP in a mp5k produces a lower rate of fire than a 110 degree #16 LP with less felt recoil.
 

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What you say is true for non-ported barrels like those mentioned i.e. a G3 with a can using #17 LP (36 degree) or a suppressed mp5k with a can using a #28 LP (80 degree). The SD is an exception to this rule due to the porting in the barrel. This design effectively shortens the barrel from a suppressor standpoint in order to allow supersonic ammo to become subsonic when used in the SD.

The general concept for LP selection is the higher the locking piece angle used the faster the action unlocks and more energy is transferred to the bolt group not unlike pressing the accelerator on car to make it go faster. To help illustrate this with an example this is the exact reason why a 100 deg LP in a mp5k produces a lower rate of fire than a 110 degree #16 LP with less felt recoil.
Excellent, thank you! This makes sense, I had not considered the ports in the SD barrel.
 

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Discussion Starter #17
Further update:

I went to my 07/02 today, so I could try my Omega upper with my Coharie suppressor. We couldn't try it in full auto, as he only had a pretty basic bullet trap, but in semi-auto, it seemed to run well. We put about 20 rounds through it. We had one shell casing get stuck (these were still the 115gr). So I think it might need some break-in, but otherwise seems to run. It actually sounded pretty good, especially since we were shooting indoors. It was very quiet compared to my Coharie SD, which led us to discover there wasn't a rubber sealer gasket on the Coharie's trunion. I guess it makes a huge difference.

So, it looks like it was my fake can all along. Looks like I need a new one (or just leave the SD in the safe until November).
 

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Come to think of it... I think there are some issues with the fake cans not being able to be screwed down quite far enough to function exactly as required. It cannot quite seal up tight like it needs to?

A year or so ago Fargo here on HKPro was modifying them slightly so that they DID work properly, as they wouldn't with SW made guns, which yours is probably pretty close to.

That might be the fake can issue actually. He did one for me and it worked fine, I just cannot remember all the details. Sorry.

Fargo???
 
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