HI,  I'm a lefty with a long gun,I have a OLY 9mm gun that runs on sten mags with a composite doughnut on the dust cover.
My question is has anyone used one of these on a 45 ACP gun(BAZOOKA BROS) the 9mm length of brass is approx=744" the 45 brass is approx=990"
Ejection problems,YES OR NO,what do you say?

I bought a dust cover kit from J&E SURPLUS it comes with the deflector, will advise results?

It just pins on.  Try it.

Wear safety glasses.

Clamshell Is Not a case deflector.....at least in 9mm it is a gas deflector.   Case in point I have a 2000 era 6450 and a Colt 10.5” 9mm upper build.  I have removed said clamshell from both. The empty cases perfectly drop out at 3 o’clock not remotely coming close to contacting me.  Even with my reduced power reloads.  I’ve seen 9mm builds that guys used regular AR upper with perfect reliability.

H

Yup, just a gas deflector. My RRA came with one and never in all the years I had it did a case actually hit it. My pistol is an open port with no deflector and I don't notice any difference.

TC-Accessories Inc. makes a rail mounted case deflector, I'm a righty but I run one on a 5.45x39 AR that was always throwing spent cases at my spotter's head with as much accuracy as it spit lead at targets. This is the best fix if you're getting brass to the face.