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JoshNC
02-13-07, 13:33
http://i12.tinypic.com/2hojyhi.jpg

http://i19.tinypic.com/4dmieit.jpg

http://i16.tinypic.com/2h4zs5z.jpg

http://i19.tinypic.com/4gq1wuc.jpg

http://i15.tinypic.com/303jxb7.jpg


I call it the Sig 556/1-2. /1 denoting its 551-like transformation, and -2 denoting a 1:7 twist. :)

I ended up swapping the gasblock for one off a SAN/Swiss 551-LB barrel. This was done after installing a front sight on the Sig 556 gasblock, only to find that Sig didn't properly relieve the sides of the gasblock - the sides of the dovetail are about 2 thousands of an inch thicker than a Swiss gasblock. What this means is that on the front sight disc that is attached to the front sight screw via a roll pin, the hole for the roll pin, which must precisely line up, does not line up because of this 2 thou difference. So I removed the 556 gasblock and installed a 551 gasblock complete with front sight.

The rifle handles great. I ran two mags through it yesterday and it shoots every bit as well as the 551 post sample we have (well with exception to the additional selector setting).

Now it just needs a rear sight. I hope this will be worked out soon. The ML2/LaRue mount is temporary and came off my 6920. Have an ML3 in LaRue RAS2 mount on the way.....Thanks Mark!
JG1911
02-17-07, 13:53
That is the rifle Sig should have brought to the market...
Dirtyboy333
03-06-12, 20:22
Sorry for the necro-post but there isn't much else going on in this section anyway.............Very nice Josh. This is exactly what i'm originally going to do with my parts kit. I think i'm going to skip welding the diopter on and just stick with the crappy screw on rail for now. I'm about 90% sure that i'm eventually going to send my parts kit and 556 to Turner Fab. for a conversion but that wont be for another month or two. They told me in an email that they will use the 551 trunion and weld on the site (if i want) or maybe a Swiss rail and the only 556 part will be the receiver. The only issue i'm worried about is the 551 barrel. I've heard that the 556 barrel is a quality FN CHF barrel and i'm wondering if replacing it would actually be a bad thing. Could a good smith tell me if the 551 barrel is in decent shape? I cant find any reviews on Turner's Sig conversions, just HK conversions.


Is there anything important that i need to know about swapping the 556 gas block with the Swiss block? Seems pretty straight forward by just punching out the spring pins.

Oh, nice job refinishing your upper!!! Did you do that yourself? I might try to Krylon mine to match but I dunno. Any input will be appreciated.
JoshNC
03-08-12, 20:39
Holy necropost. That rifle was converted to a full 552 spec SBR. The finish you see is what Sigarms initially put on the 556. It is a gray phosphating that did not match the lower's black anodizing. It slightly matched the Swiss gray lower in color but not texture/sheen.

Sorry I can't help you with Turner Fabrications as I've never seen their work. Their prices are so high that it seems one would be better served in finding a reasonably priced pre-89 550.
Dirtyboy333
03-09-12, 09:47
Holy necropost. That rifle was converted to a full 552 spec SBR. The finish you see is what Sigarms initially put on the 556. It is a gray phosphating that did not match the lower's black anodizing. It slightly matched the Swiss gray lower in color but not texture/sheen.

Sorry I can't help you with Turner Fabrications as I've never seen their work. Their prices are so high that it seems one would be better served in finding a reasonably priced pre-89 550.
OK well thanks.....Turner wants $1750 for the full conversion. Even without the conversion i would still have more Swiss parts in my gun than a WCA 551.