So I got a M4 type SP1 this weekend. It is used but seems in pretty good condition. I wanted a used one instead of a NIB cause it was a lot cheaper and I want to shoot it, not store it in the closet.

Well I took it shooting today and got a few FTEs. I got these on both Thermold and aluminum magazines. I noticed that the casing was still stuck in there and the next round was on the way up the feed ramp. This leads me to believe that the extractor isn't quite working. Any other thoughts on this or experience with this problem?

P.S., I really like this small rifle. The telescopic stock is much more usable than I had anticipated.

I've got an upper that does that only with SA ammo. The suggestions that I received were that I should check for a rough chamber.

I'd try one of those D-fender rings that increase your extractor tension.  I had a Bushie upper that had that problem, and the D-fender cured it completely.

What brand is the upper receiver and barrel? Sounds like someone may have skimped by with a lesser quality off brand upper receiver assembly or barrel assembly. My all-Colt M4 runs flawlessly.

posted by Boomer What brand is the upper receiver and barrel? Sounds like someone may have skimped by with a lesser quality off brand upper receiver assembly or barrel assembly. My all-Colt M4 runs flawlessly.

I'm not too sure how to figure out what brand the upper is. I have an Armalite carbine with an identical bolt assembly. I plan on trying that bolt assembly next. I'd try the whole upper but the front pin hole has a different diameter (smaller) on the upper.

I'm not above getting a new upper if that's what it takes. I kind of want to eventually anyway. The lower and stock look to be in very good condition.

Hey Sparky315, thanks. When I try the Armalite bolt assembly I should find out if it is an extractor problem. I hope so anyway.  

If It Isn't A Colt, It's Just A Copy

Hey man, what's this all about. I thought everything was just a copy of an Armalite, since they invented and developed the darn thing.