SIG XXX compatibilty with SIGarms 556. This parts kit fit?

[Q]

This is regarding a pistol rebuild/overhaul..

I've seen a few SIG 551 and 552 parts kits lately and got me wondering if these could be graphed on to SIGusa platform because they include the front trunnions. I know SIG XXX barrels do not fit SIGusa trunnions. They include the trunnions so I think the parts might be usable for overhauling a SIGusa by replacing the whole front end including the trunnion. I know the lowers fit so the receiver should be in spec..

1)I was wondering if the SIG 556 bolt and carrier will work with the SIG XXX trunnion?
2)Would a SIG XXX bolt be required, or carrier as well if using a SIG XXX trunnion?

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=177883586

Some kits I've watched over a couple of months.. ranging from 1500-2600.

[Peter W Bush]

OMG I want a SIG 552 so bad!!!

[patriot_man]

OMG I want a SIG 552 so bad!!!

Yes! Same here. Wow this thread has opened up some new ideas

[sd1023x]

Yeah, the barrel threading is completely different (think its the opposite way than the original 55x's and its not indexed, although by making three marks, you can index your 556 barrel). Other than the barrel threading, all the other upper parts are interchangeable between the 55x's and the 556.

https://www.cogunsales.com/index.php?page=shop.browse&category_id=11&option=com_virtuemart&Itemid=1&vmcchk=1&Itemid=1

Co gun sales sells 55x its with US made 55x profile barrels kits to convert your 556 into swiss 55x copy with the barrel threading for the sig 556 upper. Don't know if they have any 552 kits. There are companies like Turner Fabrications that do work on Sigs, but I can't/will not vouch for them. I've know some of their HK work and it was a neutral review for me.

[sd1023x]

Oh yeah, think ADCO might be able to work on 556 barrel for you. I know they have cut down sig 556 barrels from 16" to 14.5", dunno why they couldn't cut it down shorter for you. Oh wait, your working off a sig 556 pistol? If so, you can buy that kit, slap the 556 pistol upper on the sig 552 lower, refinish to match color and your gtg (I think). And of course the SBR issues.

So you don't need to get the whole kit, just a Sig 550/1/2 lower. But I don't know why you would want to do this, considering 550/1/2 magazines are pretty pricey.

[Q]

Thanks, really wanted to buy that 552 kit. The 556 bolt carrier looks like the 551 now that I think of it, haven't taken it apart in awhile. Just something I was pondering, I would prefer to do a 552p but the kits are uber rare. I got plenty of projects as is but would scrap a few for either of these. I just bought a old gun not to long ago so I will have to hold off a bit.

[sd1023x]

It our messed up import laws that make the small changes necessary. Just for your reference, a sig 556p on a genuine swiss sig 55x lower.



Found on M4carbine.net.

[Q]

Thanks!
Found this for the sling.

http://www.hkbeltfed.com/sig.html

[E-120]

Cool