When my magazine is seated it touches nothing but with a little side or upward pressure I can hear it (feed lips) scraping ever so slightly on the recessed notches on the under side of my bolt carrier.  Is this normal and if not should I have the under side of my carrier buffed in those recessees to make more clearance?

I wouldn't do anything to the rifle. If anything I would do it to the magazines feed lips.

But I wouldn't do anything unless you can't cycle the bolt, or it wont feed a round properly. If it functions properly, go to town.

The feed lips and bolt will mate to each other after a few full magazines.

What kind of magazine is it?

USGI Labelle

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Hum,..... if I did anything it would be to the magazine, not the rifle.

That way if you mess up, you just get rid of a $20 mag instead of the rifle.

Does this happen with any other magazine in the same rifle? Could be a bad, or out of spec mag.

Do you notice any wear/marks on your carrier?

Does this happen when the mag is loaded or only when it's empty?

I'm going to go see if mine do that.

Its on all of my magazines and its VERY slight touching.  I can only tell by the slightly different sound it makes when I pulled the charging handle when laying prone and dry firing and the mag touches the ground and even then only some of the time.  Its not enough to show any marks since it only happens when the mag is pressed in more after its seated or if you press the mag to one side or the other at the base.  When the mag is empty I hear a VERY light grating sound.  When the mag just hangs there its not touching anything.  When its loaded I am wearing hearing protection and hear nothing.

Mine must, because on a closed bolt it is MUCH harder to insert a mag.

Edit: the reason it is much harder is because I am used to slapping in a full 30 rounder. When I use an empty mag, it's pretty easy. Looks like there might be minor contact with my mag (SA80).

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DevL, if you have no functional problems, I wouldn't worry about it.

The carrier is made of heat treated steel.

Magazine feed lips on the other hand, even those of steel SA-80 mags are of relatively soft material, comparatively speaking.

The feed lips will soon mate(wear down) to the bolt carrier, vs. the other way around. Then one has a perfect fit. From the way you describe I would consider it a break-in issue.

In my view this event would only be an issue requiring action if the bolt carrier prevented from operating properly or was held up on its trip forward and rearward in the reciever. Or is one was having unexplained malfunctions.

I personally would not alter anything, especially not the rifle. As one could easily create a completely unrelated problem that has functional implications.

Sniper_Wolfe,

The additional force required when inserting a loaded mag is from the compression of the spring as the bullets are pushed down by the underside of the carrier... this is 100% normal.

I think I am going to not worry and just shoot the mags while pressing on the bottoms of them to insure they wont cause a malfuntion.  If everything works 100% I dont hink I will mess with it.

I had a similar issue with a USGI surplus colt upper on an Olympic lower. When I put them together the fit was great, nice and tight. I had to paint the upper to match, but it looked pretty good.

Took it to the range with some new SA80 mags and it wouldn't feed worth a crap. Threw in an old beat up USGI mag and it worked great. I played with the SA80 mags for a while, they work great in my other gun. Then just for grins I threw an Accuwedge in it.

I think the Accuwedge actual gave me a little clearance between the upper and lower and it feeds on everything just fine now.

Rather than grind on your mags and screw them up you might just try the Accuwedge first they are only $5 or $6 bucks.

My upper and lower fit together tighter than an 18 year old virgin before prom night.  There is NO WAY an Accuwedge would fit in there.  In fact I used to have one and when I tried it with someone elses upper, it locked the two up so tight we had to use a bullet tip and a hammer to get the takedown pin out.  I then threw that piece of crap in the nearest trash bin.  These are NIW Labelles so I guess I just need to break em in.

Also, can anyone post a pic of the underside of their carrier where the feed lips go?  The machining on mine is rather... crude.  In fact its the only spot on my rifle where the machineing is not spectacular.  Id like some photos to compare.

I hope when you say "bullet" you literally mean just the projectile, and not a whole cartridge.  Else, I'd not want to be anywhere near you when you're hammering away on the end of the primed case with a hammer trying to get your pin out.

Turby

Bullet loaded in brass with no powder or primer.  It was Brouhaha's takedown tool.

Mag catch location slightly out of spec? None of my Colts do this when useing Colt 30rd or Thermold magazines. Simple solution: Don't rest gun on magazine while shooting (use 20 rounders when shooting prone). AR mags make a poor mono-pod anyways (too light weight).