I built an AR from scratch some 8 months ago. I am going on 2000 rounds through it. I clean this thing when it doesn't need it, so improper care is ruled out. It feeds factory ammo feeds fine, but reloads do not. I am running my brass to .003" below my chamber size. Should I go a bit more? I am unsure, but I do know that I recently put a bit of loctite between the gas tube and gas block and it solved the issue for a week or so. It was leaking a bit much, but not now. I do not get it

What do you mean "0.003" below chamber size"?  What dimension are you referring to?  

As for "going more", unless you're talking trim length, dies are what they are.  Ain't like you can shrink 'em in cold water...........

.003" under my chamber size, meaning that my headspacing on my brass is 3 thousandthds smaller than the size of my chamber(I use an RCBS headpsace gauge to determine the chamber size). By "go more", I mean should I reduce my headspacing.....

Well, unless you've done a chamber casting, you really have no idea what your exact chamber dimensions are.  All we know for sure is that you're setting your die to move the shoulder back 0.003" further than the tightest point indicated by the gauge.

Anyway, could you provide more detail on the exact nature of the problem?  Is it that the round feeds, but won't fully chamber?

Use a small based reloading die and even then after having the resizing die touch the shell plate I screw the die in further about 1/2 turn.  

Since factory ammo runs and your reloads don’t you are obviously not doing something right.
Since you gave very little info on the feeding problem or your reloading setup it makes it hard to tell what the problem might be.

I'd be curious to know exactly what the length of the shoulders were AND the OAL of the cases cases were when loaded irrespective of what the chamber seems to be.

If your cases were 1.760 or under, then it shouldn't be an ammo problem. 1.760 case length is the SAAMI length stated as the MAXIMUM a case should be when loaded.
For example, your chamber might "seem" to measure 1.766 the way you're doing it, so cutting the cases to .003 under (to 1.763) would leave the brass out of spec and too long for the chamber. Since most factory ammo case length measures (for me) at 1.750, then that would explain why you don't have any trouble shooting factory ammo.

Now, you say that you built the rifle yourself, and we don't know how well you understand how barrel to bolt headspacing works, but if your cases were loaded at a case length of 1.760 or under and still don't shoot, then I'd revisit and check your barrel/bolt headspacing.
At least check your chamber with go/no-go gauges. You might find that the "go" gauge won't chamber which would be proof that you barrel/bolt headspacing is too short.
I might be confusing the issue because up to now I've been reference only overall case length, but the same issues apply to shoulder spacing except for the specific measurements you're going for.
Your reference to ".003 under the chamber" does indicate that you are referring to shoulder length, but look to OAL length as well as shoulder length, and if your shoulder length actually IS the problem, then I would look even closer at your original barrel/bolt installation for correct headspacing there..

For reference, I have measured brand new unfired brass, and it typically measures 1.750, and that's the "factory ammo" that most of us have no problem running through our AR's.
Since I load for several different AR's, that's the trim length I've settled upon because 1.750 is "right on" for duplicating brand new case length of factory ammo.
For case headspace, I typically size the shoulder to 1.455 using the Hornady case gauge if you would like a reference to consider.

Also double check and reconsider your powder type and charge weight. It could be as simple as not running a proper charge in them.

I'm just throwing out a bunch of things to consider as you troubleshoot the problem. Hope I made enough sense because sometimes I even confuse myself.

We need your re-load data to either rule that out as an issue or rule it in.

V

Some powders work better in semi-autos than others. Definitely need load data to help figure out what's going on. There is a reloading area in the forums might try to get this moved there.

Holy lack of information Batman!!! Help us out here OP.

That is not what I am saying at all. To get an average chamber size, you shoot 5 rounds and measure the brass. They will vary, but only by a thousandth at most. That "will" give you your chamber size as brass expands to the size of your chamber when fired. I did not say that I am setting my headspacing to .003" under the tightest, I said that I measured my chamber size(using the method stated previously), then bumped the headspacing back .003" under that value.

The round chambers fine, but when I fire it will not feed the next round.

I found when I was using low power reloads I had to install a lighter buffer to get things to cycle and feed.Either that or a lighter mass BCG,and or different buffer spring.
It almost sounds like the BCG isn't going back far enough to strip the next round off the magazine.
The Magazines may to be to blame also.
Factory loads always worked right,but I reload.

I am using the RCBS rock chucker set with the auto priming unit. I have an RCBS case trimmer and trim mate prep station. I use all RCBS dies, including the AR series 5.56 die set & swagger die. I use an RCBS case gauge http://www.midwayusa.com/product/477756/rcbs-precision-mic-223-remington, and a Hornady mic. I have read countless hours on reloading for the AR and have a mentor who has been reloading 20+ years, but he ha never reloaded for an AR. I am using Accurate LT-32 powder and  # 400 primers. I have a few rounds that feed fine, but only HPBT will not feed. Witht he exception for Barnes TSX 70 gr. They feed fine, but hornady 75 gr, SMK 69 and 77 gr, none of them will feed. Same with a few Nosler HPBT.

The load in question is a 77 gr SMK, 19gr LT-32, in a CBC 5.56 case.

The feed issue is that it will either skip the next riund completely, or grab it and it becomes wedged.

The rifel I am using is ran me $3200. Everything is American made except for the optics. It runs a carbine gas system with a spike's ST-T2 buffer kit.
My wife's little brother has an I built too. It is using a lighter buffer than mine, and it still will not feed, but I have noticed that light loads seem to have more trouble than a near max charge. The thing is, the loads in question are not light.

Does it eject the spent case?  I'm assuming the bolt isn't locking back.  Are their extraction marks on the spent case?



 

It does eject, and no irregular marks are present

Does it lock back on the last round?  Does it partially load the next case or completely miss it?        
 

One of my theories was undergssed due to a possible gas leak.  put a bit of red loctite between the gas tube and gas block and it seemed to solve it, but it only lasted a day, so I am thinking it was all a coincidence and it really did nothing at all. IDK.

It does lock back, and both. 1/2 the time it misses, and 1/2 the time it wedges the next round

Did you notice if it's locking on the bolt or on the carrier?  If it's missing the next round half the time it shouldn't be locking back on the front of the bolt.  It sounds to me like your load is under pressure or the powder your using does not have a pressure curve conducive to proper function in an AR.



The fact it works fine with factory ammunition indicates it's not a gas leak problem.



 

Right you are on that one. The powder I bought was supposedly popular in ARs, specifically competitions. I will just have to try something else ans rule that out

Are you at max load? Competition guns often times use lightweight operating systems.  Many are also rifle length gas systems.  What gas system are you using?        
 

I usually run middle of the road loads. Carbine gas system

Are your loads at max c.o.a.l. ? I have had problems with max length ammo and pmags. I have better luck with metal 20 round mags.

Solved... I think. Further testing needed before I know for sure, but I do know that I fired my first 77 gr SMK that actually cycled properly. Max was 19.3gr ad this was @ 19.1. So in order for heavier loads to cycle, I am going to have to load near max. Does that make sense?

Makes sense to me,but I'm a 13er both in the AR platform and cartridge reloading. Shotshell loading since '74

It makes sense.  
Optimal load for any bullet is also dependent on brass type and brand, chamber size, and even primers, etc, etc.  If you started low and are working up safely, watching for any signs of overpressure, you should be safe.  
The recommendations in the manuals are based on pressure readings in test chambers and are appropriately conservative to avoid overpressure situations.