I had my Colt at the range today and after the slide locked back I inserted a fresh magazine (a Wilson 47 7 rounder) and I hit the slide stop the gun only chambered the new round half ways. The recoil spring is a 16# one and in good shape. It did this only twice but after I hit the slide stop instead of "riding" it i.e. leaving my thumb on it as the slide went forward the problem stopped,could I have inadvertantly engaged the slide stop as I was using my thumb differantly due to it being injured? Function otherwise was fine no faliures of any kind I have the chamber polished,so I know the chamber isn't to tight and the gun was clean.
Next time it happens, check the case for a crescent-shaped mark just a bit below the case mouth. If the problem just started, it's probably either a weak mag spring or there's gunk built up in the extractor channel, not letting the extractor cam open to let the rim slip under it. Remove the extractor and clean the hole with a blast of carburetor cleaner and a .22 rimfire pistol brush. Just push the brush through. It'll pop out the other end into the ejection port. A rifle brush may be too long.
If that's not it, report back and we'll go from there.
Hey thanks for the reply. I was using brand new Wilson 47 magazines so I don't think its the mags. Also I'll check the extractor tunnel for gunk I had the chamber polished so I don't think its a rough chamber issue either. Tuner I think my extractor is tension properly per your instruction it passes the extractor tension test, and hasn't malfunttioned since I had the new extractor put in. I was using Magtech 230gr ball ammo if that helps at all? Does this ammo have any known problems like this?
If your thumb is pressing on the side of the slide that would slow it as it went into battery. This, combined with an almost fully compressed magazine spring (I presume the magazine(s) were topped off) could do it.
With a magazine loaded and inserted, pull the locked slide back just enough to free and release the slide stop and then release it. It should go into battery, and if it does you have a clue.