no FSB rail/upper alignment

[col.1981]

If your running a front sight on a rail and have negligible alignment difference between the rail and upper receiver do you go for and sight it in, or try and get it 'perfect'.

I know there is a tool for the proper alignment and you can use a carry handle to help, I don't have either (but will get it right one way or another if need be). I tried using a ADM Micro mount but that didn't seem to help (probably too short). This particular setup is real close but still a little off (L to R, visibly).

Never ran into this previously as I've always ran a FSB.

Thanks for any advice.

[Robb Jensen]

What rail? I use the KAC URX vice jaw to keep the rail in alignment for installs.

[col.1981]

It's a Centurion C4 12". The upper is a Rainier Arms Gen. 2.

[col.1981]

Here's a crappy photo of the setup, which probably won't help. I'll try to get a few looking down from either side when it's daylight outside again.

http://i111.photobucket.com/albums/n136/greenroundhill/e6c5dbb0.jpg

[Guns-up.50]

A removeable carry handle will also help align the rail if you have one... bonus many rifles come with them.


If it were me I would want it perfectly aligned. Your accuracy will suffer otherwise

[col.1981]

http://i111.photobucket.com/albums/n136/greenroundhill/a9e50d4e.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/052738c9.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/bc5c9cfb.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/603ee395.jpg

[ASH556]

Call Centurion. Something's out of spec. The way that rail's designed with the anti-rotational tabs on either side of the receiver and the way it attaches to the barrel nut, you shouldn't be able to install it cock-eyed.

ETA: I don't see any misalignment in the pics. Have you shot it? Will the sights zero?

[justin_247]

Looks good to me.

[Quiet-Matt]

That's about as close to perfect as you are going to get in my opinion. I've never seen a rail that was 100% perfect, due to differences in manufacturing. This is a good example of why NOT to bridge the gap with an optic BTW. Shoot it and get it zeroed, I'm sure it's fine.

[rob_s]

Shoot it and check.

[col.1981]

Here are a few more photos.

Zeroed at 50yds, no problems. Windage a little farther left than I'd like but I think it's GTG.

Thanks for the advice guys.

http://i111.photobucket.com/albums/n136/greenroundhill/779cd8a6.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/3e20bbac.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/08a13127.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/bd51549f.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/d16c2ce7.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/27509054.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/e4509fe8.jpg
http://i111.photobucket.com/albums/n136/greenroundhill/ccb2573f.jpg

[Bizzarolibe]

Here's mine for comparison (C4 12"):

http://i40.photobucket.com/albums/e236/Snarky15/SDC11734.jpg

http://i40.photobucket.com/albums/e236/Snarky15/SDC11735.jpg

http://i40.photobucket.com/albums/e236/Snarky15/SDC11736.jpg

It's zero'd at 50m. As you can see, the rail is a fraction of a mm off.

[BSWilson]

I'll bet your barrel nut is a fraction of a degree off, not enough that most would notice or would affect gas tube alignment, but enough to require a few clicks correction in your sight.

If you have the tools available, reinstall the bbl nut. Or not. It's pretty negligible and there's still no guarantee that reclocking it would correct it (minor as it is).

[bp7178]

I have a factory assembled SR15 upper thats a tick off as well.

I've never seen any anti-rotation tabs make contact with the upper. They are always a bit wider.

The only seperate rail/upper combo I was able to get in perfect alignment was a Vltor MUR and a DD RIS-II.

Troy rails (IMHO) are the worse for this. I've owned two Troy rails, a TRX and a MRF (I think that's what it was called), and there was always a slight height or width difference between the rail and the upper.

Having fit a few different rail systems, I appreciate a good fit. I also see the brillance of the way the Larue OBR series of rifles mates the rail to the upper.