Okay, so here's the deal. I really, really want a Sig 55x in 7.62x39. That seems like barrels 'o fun! However, in Canada, the Sig 55x series is prohibited, except for the ones that aren't, and even those are going to be prohibited soon. Confusing, I know. One of the models that we cannot currently get is the 7.62x39mm series. However, since only the upper is serialized, I am able to import lowers and any parts/barrels/etc.
My question to the great community here is: which parts from the 7.62x39 are the same as the 5.56 version? And of the parts that are not (ex. bolt), which are compatible in the 5.56 upper receiver, if that makes sense. Also, are my upper receivers compatible with a 556/553r lower?
I own 2 Swiss 550's, as well as have a Swiss 552/3 (I'm actually not sure which one it is) on the way. I would be willing to convert either model to a 7.62x39 version. Would my simplest bet be to find a 553r/556xi lower, and mate it to my upper, and then swap out the necessary parts? Or is this just an idea that is impossible?
Originally posted by DSgrouse: boy, I am not sure. The lower's mag well mag release are considerably different.
The bolt, op rod, and gas key if i am not mistaken are different. The barrel, I will be watching to find out.
Good to know. I was pretty confident I would need to source a lower, I'm just hoping that the different model uppers and lowers will mate. Any idea if those different parts will fit and function in the 5.56 upper?
As for barrel, I would like a factory barrel, however I've got a smith who can make me a 7.62x39 barrel if I need.
The upper and lowers will swap on all the semiauto 556, xi & 7.62x39, I’ve got all 3. I’ve used a early 556 lower on my 556xi 7.62 upper with a C-Products 7.62x39 AR mag and it functions perfectly.
If you can get a 7.62x.39 lower, barrel & bolt it should work, unless they’ve done something wonky with the barrel threads ... also you may need to open up the ejection port for the fatter cases ... some people had problems with that on the early Russian guns mown here in the states.
If you really want something you'll find a way ... ... if you don't you'll find an excuse.
I'm really not a "kid" anymore ... but I haven't grown up yet either
Originally posted by kimberkid: The upper and lowers will swap on all the semiauto 556, xi & 7.62x39, I’ve got all 3. I’ve used a early 556 lower on my 556xi 7.62 upper with a C-Products 7.62x39 AR mag and it functions perfectly.
If you can get a 7.62x.39 lower, barrel & bolt it should work, unless they’ve done something wonky with the barrel threads ... also you may need to open up the ejection port for the fatter cases ... some people had problems with that on the early Russian guns mown here in the states.
That's awesome to hear, thank you very much for the information, that's exactly what I needed to know! Now off to find a parts gun!
Hopefully I'll have a nice Canadian legal 7.62x39 Sig to show off in the near future!
Let me know if you ultimately find a source of 7.62x39 barrel and bolt in the US. Mine has terrible accuracy. Sig refused to fix it. They won't sell me a new barrel (the problem). And I've been (casually recently anyway) searching for a new one. No luck in the usual places I look for out of production Sig parts.
“So in war, the way is to avoid what is strong, and strike at what is weak.”
Originally posted by hrcjon: Let me know if you ultimately find a source of 7.62x39 barrel and bolt in the US. Mine has terrible accuracy. Sig refused to fix it. They won't sell me a new barrel (the problem). And I've been (casually recently anyway) searching for a new one. No luck in the usual places I look for out of production Sig parts.
And this is the problem, the 7.62 556xi was in production for such a short time, there isn't anyone parting them out.
If you really want something you'll find a way ... ... if you don't you'll find an excuse.
I'm really not a "kid" anymore ... but I haven't grown up yet either
Originally posted by ianfroese: I own 2 Swiss 550's, as well as have a Swiss 552/3 (I'm actually not sure which one it is) on the way.
I'm a bit confused by this statement as the 552 and 553 have different gas systems that place the piston and action spring in opposite locations, and should be easily identifiable.
quote:
Originally posted by ianfroese: I'm going to re-do my question, seeing as I've found oodles of 556xi's in 7.62x39 on various websites, for really not a whole lot of money.
Will the 556xi lower mount either a Sig 550 or 552 upper to it? And if so, will the bolt carrier and bolt from the 556xi upper work in the new upper?
Anyone have a 552 and 556xi they want to do some experimenting on? Wink
I don't have a 556xi to reference so take my comments with a grain of salt...BUT, a plain jane SIG 556 lower in 5.56 mm will mate to a SAN SIG 55X 5.56 mm with only slight modifications. Presuming that the 556xi has identical or close dimensional characteristics I would presume it would work as well...HOWEVER, I can't answer the question as to whether the same would be true for mating an upper and lower designed for two different calibers.
The bolt for a 556 and 552 are interchangeable in 5.56 mm, and I believe the 552 and 553 bolts are interchangeable, but again this references 5.56mm bolts only, so I don't know how a 7.62 bolt would factor into the equation as far as functioning.
You might consider referencing a parts break down for the two calibers and checking for parts commonality...or, you might consider contacting SAN.
Posts: 7324 | Location: the Centennial state | Registered: August 21, 2006
Originally posted by Modern Day Savage: I'm a bit confused by this statement as the 552 and 553 have different gas systems that place the piston and action spring in opposite locations, and should be easily identifiable.
I don't have a 556xi to reference so take my comments with a grain of salt...BUT, a plain jane SIG 556 lower in 5.56 mm will mate to a SAN SIG 55X 5.56 mm with only slight modifications. Presuming that the 556xi has identical or close dimensional characteristics I would presume it would work as well...HOWEVER, I can't answer the question as to whether the same would be true for mating an upper and lower designed for two different calibers.
The bolt for a 556 and 552 are interchangeable in 5.56 mm, and I believe the 552 and 553 bolts are interchangeable, but again this references 5.56mm bolts only, so I don't know how a 7.62 bolt would factor into the equation as far as functioning.
You might consider referencing a parts break down for the two calibers and checking for parts commonality...or, you might consider contacting SAN.
Good information. I suppose I could talk to Swiss Arms and see what they have to say. I wasn't sure if they would want to answer too many of these questions for liability reasons, but I guess the worst they can do is say no.
As for not knowing whether it is a 552 or 553, I bought this gun sight unseen before our new even crappier legislation comes into effect. In Canada these are known as a Swiss Arms CQB, which I believe come as a 552, however some guys have swapped to a 553 gas system, if that makes sense. So until I have the gun in hand, I'm not 100% sure what I am getting. It is likely a 552 system, though.
Hate to hear about new gun control measures being implemented anywhere, especially in a country in which you could still get some relatively nice guns like the 55X series...so I can understand your reasoning on jumping on a deal prior to the law taking effect. I presume that currently owned guns are grandfathered in under the new law?
Curious that the seller couldn't provide you with a model number or which gas system was on the rifle in question...but If I was going to roll the dice and buy a gun without knowing all the details about it the 55X series is one that I'd probably do that with.
Good luck with the project and keep us updated on how it goes.
Posts: 7324 | Location: the Centennial state | Registered: August 21, 2006
