I have an ar with 5.56 chamber that has over 1000 rounds through it. Rifle runs like a sewing machine and has never failed. mostly handloads using lake city brass and 55 gr with near max load of varget. Seems like brass does not grow very much from multiple shots. Can get more than 4 loadings before it's getting close to max length when trimmed to .007 under max length. Is this an indication of headspace on the tight side ?

Since they are being reloaded it would be more related to how much they are being resized, so could be FLS die and how you've adjusted it.

I never did a full FLS for my M14, my cases were a snug fit but also reliable feeders - the FLS die wasn't screwed into the press for max FLS if you know what I mean. I check case length and adjust to max after each firing so don't really know the figure for how much they stretch. I use my caliper as a go-no go length measurement.

I'm using full length die just barely contacting shoulder.

That don;'t mean much; have you heard of "tolerance stacking"?

Headspace is the difference between chamber and ammo.
As Jkob alluded, tolerance stacking can be a problem even if everything is
within spec. Ammo is a bottom of spec, chamber at top? Too much slop and problems.

I shoot a Rem 660 in 308, lost a casehead and had headspace checked 30 years ago.
The bolt will close on a no-go with a .010 chip on it.

Yep, she has headspace issues!

Went to neck sizing, then a FL die to bump the shoulder when they get snug.
Some of my LC match brass has been loaded 5 or 6 times, never separated another.

You rifle is probably fine.
Your loading process is definitely fine.
All that's really important.

I don't know what you mean by tolerance stacking

Jeeper,

The throat is what wears out, and if you only have 1,000 rounds through it, that should be fine for a long time.
Now keep in mind the lands on a 5.56 are a lot further away than if it had been a 223 chamber.

Headspace wise if you want to get an idea of where it’s at get a Hornady headspace kit that fits on a micrometer and check factory vs. fired... your headspace will be a bit more than that shows.

Headspace wise .001-003 over a go gauge that is hard to close bolt is where a new gun starts, MOST (not all) field gauges are .010 over the go... (so that’s your safety margin for most rounds).
No-go’s are either .004, or .006 over the min. Chamber length... most people don’t know that... and Ideally rifles don’t close on those... some older guns will, but the question on safety is really how does the Field gauge - it if goes in you have a problem.

That being said - I’ve seen brass “shorten” instead of stretch so there aren’t any guarantee’s when inferring non-stretching brass means good headspace.