I just got a Banshee in .40 and picked up their Action Tuning Kit, which has 1 oz, 2 oz & 3.5 oz weights you can add to the back of the carrier.  They are held with a roll pin.
Here

Does anyone use this?  What weight do you use?

BTW:  Just received their new Zeroed 2 port brake.
Here
Will replace the original one port brake.

using the 2oz weight with my 9mm Banshee and Omega 9K suppressor.  Works fine.

Installed the 1 oz. weight today on 40 Banshee.  No suppressor.  Also installed the CMMG Zeroed 2 port brake, replacing factory 1 port brake.

I use the heavy weight on my 9mm, plus a 9mm buffer, but I'm exclusively shooting it suppressed and trying to delay the bolt opening as much as possible.

I purchased the kit for my 45 CMMG and used the 2 oz weight. Plan to go to this setup however.

https://c3junkie.com/?page_id=280

I've done the most testing for the 9mm CMMG RDB and found adding weight makes it too bouncy.
Like MP5 (different locking pieces), the best way to delay the opening is mechanically instead of throwing mass at it.  CMMG also posted about this when it first came out.  They mentioned the possibility of releasing different bolts with different angles to control the delay.  I suspect that offering the bolt weights is much easier for most customers and less of a headache to support.
I use the 40SW bolt to run 9mm which has less aggressive angles this effectively delays the opening without increasing reciprocating mass.  Using the .40SW bolt in 9mm only works when I mount the suppressor w/ my buffer and spring combination and won't run without the suppressor which is exactly what I want.  It is basically balanced for this buffer / spring / suppressor combination.

I have .45 specific CMMG RDB info on my site at this link:
https://c3junkie.com/?page_id=841

...but yes I'm basically running the same setup for .45 as I am for 9mm.  Although for full auto 9mm I use the weaker 300BLK Tubb flat spring which is too weak for .45.  For semi auto 9mm or .45 ACP semi or full auto, I would use the 556 Tubb flat spring.

No bolt weight used in 9mm or .45 which again means no additional reciprocating mass.

Note that while the 9mm and .40SW have noticeable cyclic rate increases of around 60RPM when suppressed, there is no noticeable increase in the cyclic rate in .45ACP.

There also doesn't appear to be any reports that I have seen of the ejector spring failures in .45 like their is with 9mm/40SW and 10mm....all of which have higher pressures than .45 ACP.

For .40SW, it has been a real pain to try to get it to run reliably like my 9mm or .45 ACP.

I have a .40SW specific page here: https://c3junkie.com/?page_id=854

I still don't have faith in my .40SW CMMG RDB setup.  For me it needs to run a SMG match which is around 4 - 500 rounds of full auto suppressed with zero malfunctions.  

You can see on my site, that I am running weights in the .40SW while I do not run weights in 9mm and .45ACP.  I had to go to a custom tungsten weight of 5.1 oz but even then it isn't 100%.

I am also using a factory CMMG Glock lower as well as Glock mags and ETS mags.

The 10mm came out after the .40SW.  Note that the 10mm RDB's come from the factory with a bolt weight installed.   I do have a friend with one and it has slightly less aggressive aggressive angles than my .40SW.  My last ditch effort is to borrow my friends 10mm bolt and try tinkering with it.  Basically do the same thing I did for 9mm.  Run the 10mm bolt in .40SW for a dedicated suppressed build and hopefully go down in bolt weight.  However, with the availability of primers, I'd rather keep shooting 9mm instead of .40SW....so not really a priority for me.

I tried the 1 oz. weight in carrier and Zeroed 2 port brake yesterday with Remington 180 grain FMJ, which has slightly less muzzle energy than Winchester 165 FMJ.  Had a number of failure to fully chamber using Glock factory 22 round mags.  Going to try the Winchester 165.

It ran more reliably without the weighted carrier.  Action spring and buffer are factory.  

Ejection was approx. 4 o'clock with Rem 180.  With factory 1 port brake and no carrier weight, ejection was 1 o'clock.

UPDATE:  .40 Banshee ran like a champ today, even with H buffer.  Zero malfunctions.  I was using a 15 round Glock mag instead of 22.  Not sure if that matters.

Since std buffer is 3.0 oz and H is 3.8, may go from 1 to 2 oz carrier weight and back to standard buffer.

Failure to fully chamber is what I've been dealing with as mentioned on my site.

How many rounds are you talking about?  As mentioned on my site, I've run several hundred rounds in full auto with various buffer / spring configurations with zero malfunctions then it starts happening again.  It hasn't made it through a 4-500 round SMG match without a malfunction.  

I think maybe I need to send it to @mad-machinst.  He did a .45 CMMG barrel for me and it feeds great.  Maybe he can do some magic for my .40SW.

Today I just ran 40 rounds, 5 or 10 at a time, all semi-auto.  Used Win 165 FMJ white box.  Zero malfunctions, but accuracy was not as good as Rem 180 FMJ.  Will try some American Eagle 165 FMJ.  It is advertised as almost 470 ft lbs of muzzle energy, which is 60-70 more than other 2.  I would expect it function well.

I've heard nothing but good things about mad machinist.

Yeah no offense but I don't think 40 rounds is enough to call it good....keep an eye on it and good luck

I think that I will remove the 1 oz carrier weight and add the 2 oz one.  That way I can go back to a standard carbine buffer.  Looking forward to trying the American Eagle 165.

There is a huge difference in muzzle energy from various manufacturers and bullet weights.
I saw some import .40 180 at Academy that was listed around 360 ft lbs.  That's weak and 9mm levels.  Remington, CCI and Winchester are approx. 400 +/- 10.  The Federal American Eagle 165 is shown at over 465 muzzle energy.  That's a 100 ft lb swing.

I see no difference in tuning your rifle or pistol to your ammo vs. tuning your reloads to your rifle.  My baseline for function will likely be Winchester White Box 165 grain.

BTW:  I do like the CMMG Zeroed 2 port brake over the factory CMMG one port brake.

I tried calling and didn't get an answer.  I'm sure you are busy in the shop.  Sent you an email with my contact info thanks!

ETA:  Spoke to Rudy and have my CMMG .40 barrel and BCG in route for him to try to work his feed cone magic on it.

I have a 22 round factory Glock mag that I bought for my Lone Wolf carbine and I never loaded it past around 18 because it never worked.

Thanks for this info. I agree with your premise completely.  

I just ordered a 40S&W bolt from CMMG to do some testing on my semi-auto suppressed 9mm. (That bolt is expensive, but much cheaper than an H&K SP5! )

I'm going to try running it on a lower with a standard A2 rifle buffer, buffer tube and spring assembly (without all the CMMG tuning weights of course).

Have you noticed any additional wear using the 40S&W bolt?  I'm assuming the extractor is still working OK, even though the case head would be larger on 40 vs 9mm?

No additional wear using the 40SW bolt.  Extraction works fine.  However, note that I'm using a custom barrel that I had headspaced to minimize the slop that all the CMMG RDB's I've seen have.  I still have two original unmodified CMMG 9mm RDB barrels and I seem to recall that the 40SW bolt would work in them but I then have early ejection spring failures so then went to a custom barrel.  Since the custom barrel doesn't have the headspace slop, it doesn't have that initial 'shock / impulse' and wouldn't run with the spring loaded ejector.  So I use my custom fixed ejector in that setup which has been great.  Extremely soft shooting (MP5 soft) as well as an excellent suppressor host.  Just not an off the shelf setup.  

I don't think I've tried a standard A2 rifle buffer.  I think that may be too heavy.  Good luck.

I read about your ejector spring failures. I'm hoping that your ejector spring issues are due to you shooting full-auto and that my semi-auto, which is pretty babied  for the most part and doesn't have a huge round count, will not experience that. (fingers crossed)

I hadn't considered that. I was thinking about the longer spring. I'll remove the weights. Supposedly that should be about the same 3.0 oz weight as a carbine buffer. If I need more than the 3oz, I can tune with the CMMG weight kit.

Did you ever try any weighted buffers with your A5 setup or did you go straight to hydraulic?

Several semi auto shooters have the issue as well...on the flip side several guys in excess of 3K have no issues also.  That is why I suspect the issue is inconsistent headspacing.  As you can see on my site my early barrel was very excessive and I convinced CMMG to replace it as it was eating parts and would extract rounds w/ no extractor installed.

I would recommend just using a Tubb flat spring.  

I tested a lot of mechanical buffers including the A5's before settling on the hydraulic and none were as smooth.

Thanks Amphibian. I'll check headspacing as well.

I also may try one of those Tubb's flat springs.  I have a few SBR lowers, so I can compare both the rifle and carbine length buffer systems.

Though my primary goal is slightly different than yours. I'm trying to optimize the system for pleasant suppressor use, delaying the bolt as long as possible without inducing malfunction and get as much of the gas out through the suppressor as possible before the bolt unlocks and opens.

I use this gun as a cheap and quiet way to practice shooting ARs at under 50y.

Let me know how that goes....I haven't seen a CMMG RDB that doesn't have 'excessive' headspacing....just some are worse than others.
This link on my site may interest you: https://c3junkie.com/?page_id=977
A great suppressor host was always one of my goals as well.

^ Thanks again Amphibian!  I appreciate you so thoroughly documenting all of your testing.