9mm AR-15 short cycle

[kamikazeak47]

what causes short cycle problems in 9mm AR ? bad ammo ?

[Epinephrine]

Im thinking the fact that the weapon was designed for 5.56 but was downsised to 9mm is the problem.

This kind of stuff happens alot in handguns when a company designes a gun around a big(.45) or small(.9mm) round then tries to create another weapon with a different calibur but uses all the same parts exept barrel, mag, and slide.

[Rew]

AR is a stright blowback design. Low powered ammo can cause shot cycleing. American ammo tends to be loaded light, why? I have no idea. NATO standard is a 124 grn bullet at 1250 FPS from a pistol barrel. American 115 grn +P might make 1150 FPS. Try some NATO standard loads or get a lighter recoil spring.;)

[kamikazeak47]

I was thinking about removal of the recoil buffer weight. make it lighter. what do you think ? all I need to do is remove the roll pin and take out some washers.

[Rew]

That may help, but go slow, and be careful.;)

[MACVSOG]

One of the biggest problems with the 9mm uppers short cycling is due to the chambers being too tight or due to there being a flaw in the chamber when it was reamed out at the factory. I have had to have a number of my 9mm barrels have a gunsmith ream out the chamber to proper dimensions, or have him polish the chamber. Here is a way that you can polish your chamber on your own. Take a bunch of 9mm rounds and roll them in Flitz. Let them dry, and then run them through your 9mm upper. You may need to spray some gunscrubber and then some oil into your chamber if the Flitz starts to build up. This will polish your chamber and make extraction a little easier. I have had some new 9mm barrels that have had some gouges in the chamber put there at the factory when they reamed out the chamber. What this gouge does is provides an indented area that the brass can expand into when the round is fired. The brass being extruded into this gouge will then offer a good deal of resistance when the bolt goes back and tries to extract the empty brass. I have had to toss one or two barrels due to this type of manufacturing flaw. Have a gunsmith check your chamber for flaws like this, and if there are not any, then have him make sure that the chamber is opened up to proper specs, and then use the method I described with the Flitz to polish your chamber.

Charles Tatum
Alamo Professional Arms