I took my Bushmaster to the range yesterday to zero an Eotech. I had gotten one of those magazine inserts that let you load single rounds. Pretty handy, but I remembered reading somewhere regarding a semi-auto pistol (Glock IIRC) that letting the slide slam forward on a round in the chamber was bad for the extractor.

So I pulled back on the charging handle before pushing the bolt release and eased the bolt carrier to about an inch away from the chambered round before releasing it.

Would releasing the bolt full travel have been damaging to the extractor?

Quoted: Would releasing the bolt full travel have been damaging to the extractor?

NO...

Hard on Extractor

on 1911's maybe but it will take thousands of times.

Mauser actions would be verry hard to load if not from the magazine box.

Extractors like those found on Mauser type bolt actions and 1911 type pistols (including Glocks) are designed to have the cartridge rim ride up under the extractor as the round is fed from the magazine.  On those type firearms it is better to have the rounds feed from the mag.  I said better, not required. Some older internal mag type rifles with Mauser type extractors had mag cutoffs to allow single shot loading, keeping the rounds in the mag for a real SHTF event.  Those rifles all had to have the bolt close with the extractor overriding the rim.  

Most, if not all, of the bolt faces on modern mfg rifles (bolt, auto/semi, lever) are recessed and the extractor has to override the rim, but they are designed to take those stresses.

The AR has a recessed bolt face and is designed to close on a cartridge, overriding the rim. To assure that the bolt goes into battery properly, letting the bolt ride forward by using the bolt release is the proper way to chamber a round.  So slam away.

Thanks for the info, Big-Fed.