I havd a rather sever problem with my M-4 a while back, & it turned out to be something quite simple, just not real obvious do to circumstances.
I took my mom out to shoot it, & it was a nightmare. The bolt kept locking up in the buffer tubb, it wasn't extracting worth a dern, & the mags were acting like I glued them in. I had never had such an experiance like that in all my born days with any gun, or gear.
I went home checked it all out & this is how I fixed it.
1) I put all my mags in each of my 2 preban Colt's & found 1 let them all drop freely, while the M-4 did not. So I put the tight mags with the loose fiting rifle.
2) I put a D-fender into the bolt of the M-4, & made sure I didn't use any old ammo with lots of tarrnish on the casings. Just good stuff. I checked the bore, & found it to be polished, & in perfect condition. I lubed it lightly with CLP.
3) The bolt in the stock was easy to figure out when I gave it a through going over. The off set screw for the front holes of the 2 receivers had 1/2 fallen out which was causing the 2 receivers to miss align just enoug to cause the bolt to lock in the stock. I had origanalyy thought it was a problem with the new 6 pos RRA stock I had just put on a few days prior to the shoot.
Anyway, I was able to correct it all with a little help from the members here, & using my own knowledge. I did learn a lot about things I had never had a problem with before with this type of weapon. It now functions properly as it should.
In the spirit of saving someone else some of these problems I would like to know what your worst malfunctions with this type rifle, or the M1911 pistol was or is, & how you fixed it.
Please, if you have never had any problems with either of these fine weapons don't wastes time posting about the fact, but feel free to add any helpfull hints you have learned about keeping things running smoothly for the rest of us.