9MM AR doesn't eject well

[crabo]

It barely kicks out factory ammo, just barely pops it out of the ejection port. I was running 5.5 of Unique with a 130 grain cast, and they won't clear the gun. Do I need a lighter spring, or can I take a coil or two off?

I want to shoot cast in this gun.

[lancem]

Seems strange, which buffer are you using, typically in 9mm the heavy buffer is used. Maybe try going to a standard carbine buffer?

[crabo]

The buffer is the factory one from Oly Arms. Gun has always been a 9mm

[Gtek]

If it has done this from beginning it could be several things. Gas port alignment, hole in gas tube to orifice in block, used gun with dirty ammo build up in tube, locking lugs in breech face, on and on. Pull gas tube and check for soot on or around hole, (alignment) clean well. Depending on front type of gas block, confirm orifice size from somebody and remove block and confirm size/alignment. First thing I think I would do if gun was bought used, or you have shot it a bunch, go buy a can of carb cleaner, pop rear pin, muzzle down and stick red tube through ejection port into gas tube and run about a half can through it. First good soaking and multiple hits every couple minutes on paper towels and see what washes out. Sounds like you have may have a tricky patient, good luck Doctor. Gtek

[GabbyM]

Only problem with cleaning the gas system and locking lugs is the 9mm AR's are a straight blow back design.

I'd call Oly Arms about a new spring. Would also be pretty tempted to shoot my Magma 147gr FN over full charge of AA #7.
I use a stiffer spring in my S&W hand gun to shoot them. Standard NATO ball is very stout ammo. Made to cycle the old sub guns floating around Europe. Your rifle is probably sprung to handle that ammo. Oly Arms could inform you on that.

[lancem]

Since it's an Oly Arms it should work as is no doubt. I built my own using an RRA upper and haven't had any issues. I've never shot factory stuff in it and currently I'm loading the Lee RN, think it's suppose to be the 124 gr but mine cast heavy around 130 something (been a while, I cast and loaded a couple of thousand before I moved and am still shooting them) using Blue Dot for powder. My load data is still packed away so I can't say what the load was but I do know it's a heavy load that I do not shoot in my Hi Power. I only shoot the RN in the AR so keeping them separate isn't a problem. And now that I'm thinking about it, the first time I shot mine I did use my pistol loads and I think I had ejection problems, which led me to going to the RN to help with feeding, and Blue Dot for the heavier load to enhance the ejection cycle. Thousands of rounds later that is all sort of a faded memory I'm afraid. If you want a real blast add a slide fire stock to it :)

[timspawn]

You may need a heavier load. Since the Oly system uses an ejector that rides on the bottom of the bolt and puts pressure on it, it does not move as freely as the Colt system. I would check for binding issues before I started clipping springs. I have had Oly's in 9 and 45 and they both had some minor issues that needed work before they became reliable.