So how effective is this mod? My kits run pretty good but only when bench fired. Shoulder it and the slight movement must introduce just enough bolt bounce to throw it off. Standard light strike issues.

I am running a SSF trigger as well. Lighter hammer spring needed? instead? also?

Thanks.

Considering that there are tens of thousands of .22 conversion kits from a number of manufacturers that work just fine without the ball dent modification, that should confirm to you the conventional wisdom that the ball dent modification is not needed.  Rather, it is at best, a bandage that is hiding the real cause(s) of the issue(s) experienced.

Best of luck with trouble shooting and overcoming the malfunctions.

MHO, YMMV, etc.

I think it's worth it.
I no longer need to run the ABW so the cyclic rate is pretty fast, brass rainbow stuff.

I've never tried (I hardly ever shoot .22 conversions anymore), but it is my understanding that if you really don't need either the ABW or the ball detent if the gun, ammo, and conversion are all up to snuff.  And yes, the ROF will be considerable.  Takeout the ball and spring and try it "bare back"?

I can assure you my functioning CMMG kits will not work without the ABW.  Semi mode yes. Auto not at all. The ABW can and does drag along the inside of the upper receiver. Spikes kits came with a ball detent mod instead. Does that dragging induce the stoppages when shouldered? Hence my questions.

I wonder if there is a bit of movement of your kits carrier (rail assembly) that's causing the failures when fired from the shoulder. Perhaps one of those spacers installed between the carrier & the buffer would shore it up and keep the carrier pushed forward. My kit is an old Ciener and I've added a couple of o-rings inside the barrel extension to steady the chamber adapter - no spacer at the rear tho.

I've polished the parkerized finish off the rails and chamber adapter feed ramp. I re-profiled the feed ramp ever so slightly too. I shoot the crap outta mine, so much so that I've busted the rear plate off of the guide rail assembly, broken several firing pins and worn out a few recoil springs.

Another reason I feel the ball detent is the better way to go is that I noticed peening on the ABW. This slamming / hammering effect of the ABW into the bolt and rail unit can't be good in the long run. The only hassle, for me, with the ball detent has been fabbing  or modding a spring to fit under the ball bearing. Someone probably offers them but I've just not bothered to look.

The Spike's kit I had came with the anti-bounce weight, trip, and with an uninstalled ball and spring to put in if the purchaser wanted to as the detent notch was there.  I never used the ball and spring.  Sold the Spike's kit.  A few years later got a CMMG kit.  I've always had the ABW installed when I shot the Spike's and the CMMG.  The only real issue I have my CMMG kit is the chamber adapter is tight. When I first installed it I thought I was going to break the back plate off trying to remove it.  After about 100 in-out installations there were grooves cut into the adapter.  This tightness was observed in seven different (two of them Colt) uppers.  The fit is still really tight.  (No need for the pressure plug for me!)  And the .22 chamber is tight.  I've 'buzzed' it but by the time I shoot much over 200 rounds, I get failure to feed issues and have to pull out the unit and clean the chamber.  Kind of a pain when you just want to do some blasting.  Never had any other issues with the conversion kits shooting from a rest or off the shoulder.  Magazines are another story - took a while before I got together a set that work well.

Next time I go shooting where I can do full auto, I dig out the CMMG kit and give it a try w/o the ABW.  I've never noticed any dragging from the AWB to the receiver, just the sliding on the main conversion plate that holds everything.  I hope that you can sort out your issues and resolve them.  The balance between the recoil spring force and the hammer spring force may be something to look at.

ETA:  Early on, based on what I was reading at the time (2006-2010), I went to only using CCI MiniMag 40 gr, copper plated, round nose ammo as it was considered the best performer for full auto .22 LR usage.

Finally had the chance to mod one of my cmmg kits with gorilla's ball and detent mod.  The bad news is that it will not run reliably with just the ball in place. The good news? With both the ball and ABW in place it ran perfectly.  Squeeze out as many as I wanted and never a dead hammer.  One of my coworkers had his twelve year old nephew with him. Made his day.  

I tried CCI mini mags,  AR15, and standard velocity as well as a 325 round box of Federal whatever's.

Out of of 625 rounds I had two duds, both AR15s, and one failure to feed, standard velocity. This was with my more problematic kit. Could not be happier.

A few days ago I tried the SS CMMG kit with and without the ABW.  Conversion was installed in a Colt M16A1 with its original 14.5" upper.  Using CMMG grey mags loaded with 20 rounds of CCI MiniMag ammo and doing a mag dump. both worked just fine.  Without ABW may have had a faster ROF but as I don't have a timer, I can't say for sure.

MHO, YMMV, etc.