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Here is what I would do:

Always keep the rifle pointed in a safe direction.
Clear the rifle.
Lock the bolt back, either with your fingers or by inserting an empty mag.
Remove empty mag if necessary
Insert a loaded mag, bump the bottom of the mag for a good seat/lock in.
"Whack the paddle" on the bolt release and let the buffer spring slam the bolt closed.
Check to see if the first round fed or not.

Let us know what happens after doing the above.

 

Seems like it only feeds first round 70% of the time, even with a good rap on the bottom of the mag, but runs properly after that. Also with each mag afterwards, the ftf becomes less and less common. However if i put it down to reload some mags it has a ftf again but the starts becoming more and more normal with each mag i do through. Tried all 8 mags, different ammo, a new bolt catch and spring and seem to have the same issue about 70% of the time. Ive tried pmags and yellow followers and these changes seem to help a bit but dont eliminate the issue. A little frustrating as i use the rifle for 3 gun and have lost alot of time clearing this malf up.

 

J2

First of all I will advise that 90% of the time issues are in fact caused by Magazines.

If you can find someone with an AR-15 Rifle that is reliable without question and who will allow you to do the following. I would recommend the following.

First of all if you purchased all the Magazines from one source and manufacturer it certainly could be the Magazines themselves.

Things to Diagnose issues we use in the schools.
STEPS:
1. I would try a Magazine that someone else has that works 100% of the time.
*Just because they are new Magazines does not guarantee they are good Magazines. This also goes for other parts! If this solves the issue it is due to bad magazines. Maybe they got the Magazine Notch incorrectly cut in the Magazine?

Worst case scenario, the Receiver could be 0ut of Tolerance. On one occasion the Broach that cuts out the Magazine Well in the Receivers was out of spec. 30 Round Magazines would work fine in the receivers but 20 Round Magazines would not and do the same thing you are describing. But try the below procedures to help diagnose the problem.
Unfortunately I hope not, but it could be that when Aero precision Broached the Magazine Well in the Receiver and it was off a few thousands of an inch. It is rare but I have experienced that.

2. Put their complete Upper on your Lower.
If the problem remains the issue is in your Lower

3. Put your Upper on their Lower.

This will confirm the exact area where the problem is originating from.
and also if there is any tolerance issue. On rare occasion when building a gun from scratch with various parts from different sources this can happen. Even though each part might be within Mil Spec Tolerance by themselves. By chance if those parts get put together there can still be an issue!
A good example of what I am relating to is for example an AR-15s Head Space.
We use a Go Gauge a No Go Gauge and a Field Gauge to check Head Space.
The Go Gauge the Bolt and Carrier should go completely into Battery and lock up.
The No Go Gauge should NOT go into Battery when the Bolt is closed. But if it does it is not a lost cause. We will describe it below.
The Field Gauge if it goes into Battery and locks up the Rifle should not be fired anymore.

So for example, if the No Go Gauge does go into Battery and Locks Up it is not a lost cause yet.
Head Space on the AR is totally dictated by the Bolt not the Carrier.
SO, if we have a Chamber that is 10 points oversize and a Bolt that is 10 points undersize
we would have a total of 20 points and the Head Space would be excessive which would allow the No Go Gauge to Close and go completely into Battery. But by themselves both fall within the + or - specs of Mil Spec tolerance. But if by coincidence they get together we can still have an issue. But for example if we find a Bolt that is only 5 points undersize we have solved our issue with only a total of 15 points closing the tolerance, or a Bolt that is right on the center of Mil Spec. Then the NO Go Gauge will not close and go into battery and do as it should.
Bottom Line with all parts, they must be compatible to work correctly.


03

 

The buffer kit you said is a separate part, Sure it’s good?

 

I have to agree, magazines are usually the problem. If you have some friends with different mags try theirs and find the one that work in yours. I will say that some ARs are a bit finicky as to the mag that works, I have seen several factory firearms that are just as picky as owner builds. I had one mag that worked flawlessly for about 500 rounds and then started having issues, while the other 5 (same brand) still going strong.
One thing to check is how the mag release was installed make sure that it is not binding up from being screwed in too far or not far enough. Try backing it out one round and also one round tighter if possible, see if that make a difference.

 

If you put a $.50 cent magazine in a ten thousand dollar rifle, the rifle may not work. I learned this the hard way with 1911 pistols. The woods around my range are littered with cheap magazines that I bought and subsequently discarded. Not only that, but good brand magazines can sometimes be defective too. Or a magazine may work fine in one gun and not at all in another. The first step to diagnosing any semi auto problem is swap magazines.

 

I am barely an amateur on AR's but have you checked the forward assist? I have seen an improperly installed or loose FA cause malfunctions.

 

For everyone that took the time to help, thank you! Looks like the magazine is having dificulty seating fully. It goes in and theres a light 'click' and it seems to be locked in. However, with a considerable force, if i push on the bottom of the mag it will move extremely slightly and make a good positive click that im accoustumed to. Looks like the reason it gets better is because after the first mag, the bolt is locked back and i dont have to push into it so the mag drops right in. Thank you all for your help. Ill be looking to get some p mags or at least some brand new metal ones as the ones i have must be 20 years old.

 

First off, welcome!!!
FWIW, I always lock the bolt open when I store mine and when I get to the range.
You stated that this problem happens no mater how many rounds are in the magazine. I have heard of problems with USGI and plastic magazines not seating fully when loaded to capacity with the bolt forward (for tactical reloading). That is the main reason why I always have it my bolt locked open.

I know most of us would like to know who manufactured the magazines.

Good luck with making it back up the rabbit hole, it is quite deep...