Reduce ejection port noise, suppressed 9mm ar

[utahjeepr]

I definitely agree that the scs is its own animal. While I would probably have never purchased the scs on my own, it came with the pistol when I bought it. Unsuppressed it works great, and has been completely reliable. In a gas gun even suppressed I can see how it would have it's proponents. Unfortunately for my wallet I believe it is simply out of it's element in suppressed blowback operation. While the weapon is certainly still functional the bark is undesirable. The scs is very close to maxed out in terms of mass in 9mm configuration. I can switch one steel weight to tungsten. Unless I am mistaken in the operating principles, the springs only have a small amount of control over the travel of the recip mass and have virtually no effect on the initial travel (opening of the port) of the bolt.

While I am certainly willng/interested in seeing what JP may have to say, I don't expect any game changing information. The one possibility I see is in the weights for the maxim stock scs. It appears they are able to use fewer weights on that shorter system leading me to belive that those are heavier. If they are, and lf they can be used with a standard 9mm scs without causing issues that might open up another set of options.

I have however been considering replacing the scs for completely different reasons. Namely that at least with the trigger I have (SSA-E) the reciever extension has to be removed in order to remove the scs for cleaning/lube. While this is not a terrible drawback, I would much prefer to have the R.E. castle nut staked and leave it alone, especially now that it is an SBR.

I am looking forward to learning more from JP after the holiday even if does not address my application. I am certainly glsd to hear that they are good folks to talk to/ learn from and that they were able to help you tune your 300 gas gun.

[bfoosh006]

Deleted

[utahjeepr]

Update

I did email JP, they also recommended adding mass. The limited amount I could add steered me away from the SCS. I installed a 9QT 12.5 oz buffer from heavybuffers.com with the wolf xp spring. My scale reads it at 12.4 oz, combined with the 13.6 oz JP bolt at a combined weight of 26 oz. I ordered the adjustable weight kit so I would have the option of dialing down as needed. For my application the 12.5 (.4?) works fine. Bark is gone, sound is much better. I tested function suppressed and unsuppressed with the following ammo:

Winchester 147g train and defend - train
Winchester 147g super x
Reload 124g (from a friend, no load data)
Winchester 115g WWB
Perfecta (Tula) 115g
S&B 115g

Ran fine, bolt locked back on last with all unsuppressed. Both 147g rounds, as well as the 124g reloads ran subsonic and were respectably quiet suppressed. Recoil impulse is smoother, less muzzle rise, and back on target for follow ups almost immediately.

Now to screw all this up and start looking at a PDW stock.

[usmcvet]

Well the good news is someone will buy the 9QT from you!