I have always wondered if the more expensive name AR uppers are truer from the factory than others. I don't have the means to chuck them up though.
The good news is people put together ARs from parts all the time and they work. I am sure there are bad parts out there, and problems happen, but it works out right a lot, with minimum tools for the job. I have "built" two from scratch and they work well and are fairly accurate. All I did was be careful to get the parts together right.
The "lapping" of uppers have always made me curious. I am with Mach on the fact that it seems counter intuitive to do this by hand, but the point that it is better than nothing but not as good as a lathe may very well have merit.
I don't know. I am curious though.
Interesting discussion, and I would like to see it continue in a polite way.
Posters have given the OP a very good idea of what he needs.
I think it is hard to tell by brand with so much OEM parts out there. There might be seven different brands produced in the same precise machine by the same operator.
A few that we know of mill their own parts (and perhaps for others) they seem to be pretty consistent from batch to batch in terms of receivers, mounts or whatever they make
with their CNC equipment and alloy treatment and/or finishing.
I found Mega, SI-defense, seekings and a few others to make good receivers and matched billets for perhaps a tad tighter AR.
AR15 performance, oak, noveske, lilja, colt, armalite, Lothar walter, krieger make amazing bolts and barrels. I used BAT extensions for the 308 based builds.
But there are many others like RRA, DPMS, Colt, Addax and a few others cut who knows where that worked as expected some a bit tighter and some looser yet acceptable.
I try them first and do the lapping later if I see that necessary. Never put one on a lathe because by the time I am indexing whatever I think I am going to gain is not going
to be measurable because in the end is not just the receiver that has to be true. The bore has to be true, Broaching the barrel nut has to be true,The lugs and also bolt
have to be true, the chambering job has to be well done. There are so many variables that we just trust the manufacturers to work within the tolerances (some best than others)
and do some basic verification's and put it together.
I think the brands might give you some indication but in reality do not matter that much as they are the shell for that AR as soon as they are functional and within specs.
I think the internals are a lot more important like a quality barrel and bolt/bcg that is the beating heart of the direct impingement system. On average we are blessed
with great options that only meet but exceed the quality and functional requirements of mil spec.
We see the occasional mishap and garbage parts possibly with the cheaper possible deal but luckily do not happen that often.
Look at the Les Baers ARs. They do not use any fancy receivers or handguards yet they produce some of the most accurate ARs out of the box. They are expensive but
they can shoot. It is not the shell that makes that possible. They of course cut their barrels and use the amazign geissele 2 stage trigger.
I think most people today will agree that following some basic directives, finding tight fits, truing what can be trued, and perhaps selecting some better quality internals is
going to contribute to reliability and accuracy. When I build a precision AR I order the barrel with a matched bolt and head-saced with the brass I am shooting, this
if I don't chamber it myself. This is the same principal used for a precision bolt action build.
IMO most people would agree that something as simple as a floating hand-guard is going to help a lot with the accuracy potential of the AR. You have them in all sort
of shapes, finishes and budgets. At some point the classic ones will die I think.
Something that I don't hear a lot is about monolithic uppers. Some people think that these are bought for convenience or to introduce a proprietary quick change barrel
but there is something else behind. If you are a large guy and use an AR in an aggressive tactical match or just hunting somewhere where you have to go prone and
downhill. Lets say something as simple as a 15% angle pointing down a valley to score in a steel target.. and if you are a large guy like me you might find youself that
even with a nice floating rail your poi goes up. Well, this is caused by one of the weakest points in the AR design that is the barrel nut thread / receiver junction that is
the same no matter what receiver. You see, the floating hand-guard prevents the typical disturbance from touching the barrel but the hand-guard is still attached to
the same thread as the barrel nut holding both the barrel and the hand-guard in place. If you put enough downward pressure (large guy + prone + shooting downhill )
then the down force will increase and the actual receiver will flex. It is not that strong no matter what brand because the section and threads have to be the same.
So this is one of those areas where one might consider a monolithic upper where the anchoring of the hand-guard is separated from the barrel nut or it might be a single
piece all together. But if one doesn't want to expend extra and wants to increase the rigidity of the receiver union one could take a shallow raiser and using a
handguard with a top rail clamp both together. This should never be done by the optics mount or rings. Those should never touch the handguard rails or this piece.
Most people are not going to worry about this to shoot from a bench of the average hunt or 3 gun drill but it is something that can show up in those situations.
I think that everything really has an impact to one degree or another and one just needs to take some time to see if improvements are needed and then tackle those
areas where some improvement can be made. I don't think there is one single recipe for everyone or everything but taking the time to get to know the rifle, the round and
perhaps taking some professional training that is often overlooked, the experience with any AR is going to be a nice one.
In reality the AR is a very well designed platform and inherently accurate and that is why so many of them and with minimum care and consideration shoot
pretty well. But still there are a few considerations and tips that one can follow to improve if needed.
Assembling the AR yourself from scratch, talking to folks and studying are very good steps towards improving on everything.
