There was a thread a while ago complaining about the "sproiiiing" of what most concluded to be a healthy AR. I have built a bunch and shot many and don't really care for that tinny sound. I noticed that it is not really present in a 20" in contrast to a 14.5-16", which is a noisy "sproiiiiing."  My comparisons involved a variety of AR15s with standard A2 stocks only (no telescoping or fixed telescoping) and barrels of 14.5 to 20 ".  
It seems that the location of the gas block in a 14.5-16" causes louder recoil spring noise.  In contrast, the 20" spring noise is not even noticeable. One Ar tested (the smoothest cycling AR that I've ever fired) was a 16" (cut from a 20") Kurts Kustom KGW (Kurtz Gewehr).  That had no spring noise and an enlarged gas port at the end of the 16" barrel.

So, is it truly the gas port location that affects the recoil spring noise?

NO, the sprong noise is the buffer going down the receiver extension, compressing the buffer spring and the spring rattling/scraping down the inside of the tube.

Depending on how the spring, buffer and tube are lubed will determine the amount of noise that you will hear.

Basically, lube the spring, buffer, and tube with a thin coat of light grease, then add a little CLP and the sprong will go away as the parts are fully coated.  

The downfall to this is if you are using the weapon in a sandy, dusty environment, the lube can attract these elements.  But since most of the AR-15's are range queens anyway, lubing these parts will not cause any problems.

Now I know that spring noise is the buffer going down the tube, compressing the spring.. and I lubed all of the buffer springs generously with Rem Oil to facilitate the scrape-free compression.

The question is...
Does the venting of gas from a gas port which is in close to the bolt (as in the location on a 16" barrel) cause a more violent recoil of the bolt and violent compression of the spring?  
Does a 20" barrel gas block and tube result in a softer/gentler venting of the gas together with a slower compression of the recoil spring?


As an aside, would a dry film lubricant in the buffer tube present any problems? It has been recommended for use in on mag springs in a dusty/sandy environment?

I have a J&T 16" Car. and I used gunslick on the buffer & spring, & I don't notice any Spring noise at all! ( With the A2 stock.)

With ear protection and a loud BANG.. I don't notice any spring noise at all.