The intent of your post is a little confusing, but I'll try to address each point.
HRnightmare said:
Last night I finished assembling my first AR upper and have a few questions.
Basically I took a spare upper I had laying around, took it apart and reassembled it. It is a PSA Freedom with Stainless barrel...
Just for the experience? To gain familiarity with the gun and the way it is assembled?
HRnightmare said:
I installed the gas tube so the hole is completely upside down as suggested in the manual I had. How do I know it is exactly upside down and not slightly angled or does it really matter that much?..
I guess you mean the gas tube hole. If it was the same gas tube it has a notch for the retaining pin. Unless you made a new hole it will go back the same way it was originally installed. As for orienting any part there are a variety of methods to ensure correct alignment. Special alignment tools, scribed lines, a piece of tape, Sharpie.... Yes, it matters tremendously! Getting the correct amount of gas out of the barrel and into the gas tube is critical to correct function. It ain't rocket surgery, but attention to detail is paramount.
HRnightmare said:
I used a armorers wrench to tighten the delta nut as tight as I could get it and align the gas tube hole. I did not use a torque wrench. Is that really necessary? Again the manual I had suggested it be cranked to 30-35 lbs but it also said wrench tightened should suffice. Thoughts?
Depends. You say "as tight as I could get it" and then "The manual....suggested... 30-35 lbs". There's potentially a lots of difference in those two extremes. For me, as tight as I can get it is something over 250 foot lbs of torque. For my wife it's about 90. Either is way too high for an AR barrel nut. Some folks have a pretty good sense of how much torque they are applying from long experience. Others never have any sense of that. My dad was that way. I can't count the number of stripped bolts and broken parts that he created. If money is an issue it's easy enough to fabricate a "poor man's torque wrench" that will keep you out of trouble. A scale, some sand or other weights, a bucket, and some wire or string to hang it from the wrench handle. A little ingenuity goes a long way.
HRnightmare said:
Last question is on the head spacing. I do not have a head space gauge so it is not head spaced. It is all assembled properly and is not a hodge podge of random parts jammed together. It was factory assembled by PSA and sent to me only for me to dissasemble and reassemble. Is head spacing a real concern? The manual I used to reassemble never mentioned it.
You can't headspace without having (at least) the bolt head that your going to be using with the rifle. Assembly has little to do with establishing head space. For an AR type gun it is based on the correct machining of the parts and how close they are held to the established dimensional specs. The manufacturers do a pretty good job of that, but mistakes happen, even with the best manufacturers. Contributing parts on the AR are the barrel, barrel extension, and bolt. Any one of them can produce an assembly that is either too tight, too loose, or within spec. Another point of concern is the misconception floating around that .223 Remington and 5.56x45 NATO are identical and that a gun chambered for .223 is always safe to fire with 5.56. Compounding that is the fact that some barrel makers improperly mark barrel as 5.56 when they are in fact chambered for .223. Not all reference sources are created equal. Not all are intended for the novice. Some might assume that you know all of the unstated parts of the process. Head space is properly check with clean, dry components and the extractor/ejector removed from the bolt for the most accurate readings.
HRnightmare said:
I have bought plenty of complete uppers and never once head spaced them. They are the experts not me.
As have many other folks. And it is usually not a problem....... usually...... You don't have to be an expert to check headspace. Go and No Go gauges along with the barrel and bolt are all that is needed. You don't really even need the upper receiver with an AR type gun since the bolt locks into the barrel extension. The upper serves only as a mounting point and "parts holder."
HRnightmare said:
Am I risking injuring myself and ruining the gun? Would you say I am cutting corners?
Yes, yes, and yes. The risk of injury is not huge, but does exist. The risk to the gun is higher. You are definitely cutting corners. The phrases "Penny wise and pound foolish" and "cutting off your nose to spite your face" come to mind.
Headspace gauges are not a large expense compared to the price of the gun or any of the components. It is never a mistake to verify your work or the work of others. Get the correct .223 or 5.56 gauges, depending on which caliber you are working with. They are different and, as noted, both have been chambered in the AR with many mismarked. Usually .223 barrels marked as 5.56. Min and max head space is different for each and 5.56 chambers have a longer throat/leade.
As noted, the torque wrench may be expensive, but if you're going to be doing more of these, it is a reasonable expense. Renting or borrowing one is an option. Auto Zone, Advance Auto, etc do rent them.
My list of minimum tooling for this would be: vise, upper receiver block, correct size/type punches, armorer's wrench, torque wrench. A gas tube alignment gauge would be nice, also, but you can use the bolt carrier with the gas key installed as a substitute. If you're handy with wood an upper receiver block can be fabricated. Just be sure that it is contoured to fit well and fully support the upper.
