Questions about my Stag 3 upper

[gunsrfun1]

I'm relatively new to ARs and just received a Stag 3H upper from Stag (http://www.stagarms.com/product_info.php?cPath=14_24&products_id=244), which I am mating to a RRA lower. I am planning to put a red dot or scope on it, with BUIS just in case. But honestly I doubt I'll use the BUIS much. I have two questions about the upper:
1) The gas block is a little canted compared to the top rail, which is perfectly level horizontally. (I checked this with levels on a flat surface.) I'm wondering how this will affect my ability to get the BUIS to shoot straight, and how concerned I should be. I would've thought this gets checked before shipping, but maybe not.
2) There is a little play between the upper and lower. Is this normal, or should it be a very tight fit.
I'm reluctant to send it back if I don't have to, because you never know what will be wrong the next time. I like that the top rail, which is what I'll be using the most, is centered horizontally.
By the same token, I paid my money and don't want to accept something if it considered "defective."
Can you answer my questions and offer any advice. Thanks.

 

[Chandy]

Yes - Gas block is lower

The STAG gas block rail is lower than the scope rail. The 3H requires a special front BUIS. I am looking to buy the TROY front with bunny ears (not the commie AK round). Talk to your TROY rep before buying just anything.

As for it being "canted" - I can only assume you mean it is not parallel to the scope rail (despite being ~5mm lower). Check with your rep to ensure this is normal.

And as for the lower and upper fit. This is not a problem unless you think it is. If it doesn't rattle while walking around - I wouldn't have a problem with it. ARs are not known for making pretty noises when fired (like the M1 Garand). In fact I just found a posting that described the AR noise as "BANG - SPOOIINGGGG!"

 

[TonyAngel]

guns, I'm not super familiar with that upper that you have. How is the gas block affixed to the barrel? Is it pinned? Set screws? Clamp on type? If it isn't pinned, it's a pretty easy fix, unless the gas block uses set screws and the barrel has been dimpled.

Can you snap a close up pic of the gas block with your phone or something?

 

[gunsrfun1]

Actually it is clamped on with two allen screws, which as you surmise probably wouldn't be that hard to fix. But the good news is that it is not as canted as I visually thought. I bought a level with an angle-measure built in, and the gas block is only ~ 2 degrees off center from the top rail. Basically it looked more off-center than it really is. I called Stag and they said that little difference wouldn't prevent me from centering the BUIS, and that the standard they use is plus or minus 5 degrees. Sounds reasonable to me, as I probably couldn't get it much better if I loosened the two screws and tried it myself. So I think I am good to go, unless anyone has other opinions on this. Always good to hear what THR members think. Thanks.

 

[TonyAngel]

guns, 2 degrees is a lot. No rifle that I build will have the block or sight so canted that you can see it with the naked eye. Maybe I'm just anal.

I'd pull the upper, lay it upside down on a known flat surface (a thick glass table or slab of granite will do) and straighten it up.

Personally, I find that their tolerance range of +/- 5 degrees to be a bit disconcerting. It's not like it's hard to get the block on straight, if you care about what you're doing.

 

[madcratebuilder]

The gas block is a little canted compared to the top rail,

If you can see the cant, then it's too much. I would contact Stag and see what they well do about it. If you are going with a scope then it's no big deal but you well never get any accuracy with a buis on the gas block. How is the gas block mounted? Set screws? Is it dimpled for set screws? Gas port alignment?

There is a little play between the upper and lower. Is this normal, or should it be a very tight fit.

Normal. Spec is up to .020 gap between upper and lower. There are several ways to 'fix' this, but it's really not a problem.

 

[gunsrfun1]

The gas block, as far as I can tell, is simply slipped on the barrel. No notches or anything that I can see. There are two set screws that go through the bottom of the gas block, below the barrel, holding it in place. The set screws are not touching any part of the barrel (in other words, there is a gap between the screws and the bottom of the barrel), so I suppose I could simply loosen them a bit and turn the gas block.
My question is, would that possibly misalign the hole in the gas block with the gas hole in the barrel and cause problems. A friend who has experience with ARs told me the gas block holes are generally twice as big in diameter as the barrel holes, so I would think this probably wouldn't present a problem.
Remember that as I said in my original post, the BUIS will be just that - backup. Honestly, I wasn't going to even buy them, because I am going to run this with optics (scope, red dot, holo, etc.) But I guess no AR would be an AR without BUIS, right?
Plus, being a newbie to ARs, even though I can turn a wrench and measure with a level, I'm a little hesitant to be adjusting things before I even know there is a problem.
Would it be worthwhile to at least shoot it with the BUIS before I mess with the gas block, to see if it's really an issue?
Thanks again.

 

[TonyAngel]

guns, a pic would help. If your gas block is affixed by way of two set screws, moving it is no big deal. The only problem you might have is if the barrel is dimpled under the setscrew(s). If it's dimpled so that the set screws cause the gas block to cant, you'll either have to send it back or change the gas block to a clamp on model.

You can shoot it like that, but it won't shoot right. Besides, it isn't setup right. If it was mine, I'd just fix it. If you aren't up to the task, I'd send it back, although they did already tell you that +/-5 is within tolerance for them.

Heck, if you want, send it to me. I'll fix it, assuming that you cover shipping. Oh, and send only the upper.

If you decide to do it yourself, be sure that you use a good hex wrench that fits perfectly. You might also want to have a heat source handy, like a propane torch or heat gun, just in case the set screws don't want to let go.

Frankly, I'm kind of surprised that a firm like Stag uses gas blocks with set screws, especially a railed gas block. You can put a good bit of torque on those when you have a front sight on it and you knock it against something.

 

[gunsrfun1]

Here's a photo, best I can do. You can see the screws do not contact the bottom of the barrel. Also, I think I used the wrong term in calling them "set screws" since they do not contact against anything. They simply clamp the gas block to the barrel. Sorry.

 

[TonyAngel]

Oh, now I get what you were saying. Your use of the term "set screws" kind of threw me off. Those are not set screws. That's a no big deal fix, assuming that they didn't over do it with some sort of thread locker.

I assume that there are exposed screw heads on one side. Hex head screws? Loosen them up and refer to the instructions above. Although I prefer to have a pinned gas block, the clamp on style is definitely my second choice. They are much more sturdy than the set screw types.