Well, I just got back from the IAO and while there I stunbled upon the Jam Enterprises (affiliate of Center) booth. I picked up one of their anti-chop cocker bolts after putting my finger in a 'cocker with it on there.
It's just a standard open-faced bolt (venturi does nothing), with four inlet holes (better gas flow and no putting the bolt in upside-down).
Now, for the anti-chop part. What they did is take a normal bolt, with a holw for the pushpin, and drill the hole longer, so that the bolt could stay back while the back block, push-pin, etc. moved forward. Now, they put a piece of plastic to secure the pushpin, then put a spring in there.
So, what happens is under normal conditions is function just like normal, while lightening a mechanical trigger a bit. But, when the bolt encounters resistance, it will stop because the spring's pressure allows it to do so, while the gun actually recocks. So, it doesn't affect anything but the bolt, then, you pull the trigger to "shoot" the gun (although nothing comes out), and the ball drops in, you release the trigger, then all is well.
Now, the ball gets a dent in it from sitting in there, but I've shot some and this doesn't affect accuracy, and at the very least breakage. Then, for the ultimate test. A 96 cocker, which is in my sig is what I put this bolt in (jah871 has one for is freeflow, but doesn't have air). This isn't some super-low-pressure Shocktech cocker, this was an ancient cocker. I pulled the trigger to open the bolt, then put my finger in there and let the gun recock. Then I pulled the trigger and my finger was fine. I did about 20 shots.
Now, if you put your finger all the way forward, so the bolt has some travel, it may hurt a bit, but when it's right up against the bolt, you're fine. Granted, this is not as nice as lvl10, but is much more simplistic due to the fact that the cocker is a closed bolt design.
So, go to their website at www.arbbolts.com and pick one up. Keep in mind though, that this affects the timing of the gun a tad. The cocking rod must be adjusted back a bit as this bolt sits a bit forward. You can still fire balls, but it won't feed properly and the bolt will have to do its job too much.
I got my clear polished bolt for 42.50, and the last-day clearance was 40.00, but they're available for 45.00 up to 75.00 (65.00 for the nickel bolt plus 10 for teflon, which teflon is worthless, the guy even said, but go for it).
Finally, a TRUE drop-in product that fixes us 'cocker owners' ball-breakage problems. I haven't broken a ball in 3 cases of Big Balls (broke a few with Premiums), but this is extra insurance that even with short-stroking I won't break. This is also good for people just starting out on 'cockers who break a lot due to shortstroking, but even for more experienced trigger finger's, it's nice to know that if I'm sitting in an awkward position and pull the trigger wrong, my balls won't break.
You can set your recock pressure as high as you want for a higher ROF because the recocker pressure won't affect the bolt's spring, as they work independently.
The guy who [helped?] design the bolt said that if my bolt ever breaks he'll send me the parts or I send it to him and he'll fix it and pay for shipping both ways, and he took my address to send me any updates, so I hope his word holds true. But anyway, go out and buy one of these, they're great.
*Edited for paragraphs*