New Bolt couple 100ths longer
Just my two cents, but here is what fixed my HALO B issues:
1. The balls are rolling BACK, off of the COPS sensor, not forward past the detent. They settle into the stock bolt face, letting the next ball in the stack fall forward slightly, which is then clipped when fired. This is only a problem with the HALO because the next ball in the stack cannot go back into the feedtube since it is under pressure, sometimes a LOT of pressure, try using your thumb to guide the ball stream on a HALO not on the gun like a waterhose, I can get them to fly about four feet in any direction.
Solution #1 - Drill center of stock venturi bolt (I used a 1/8in drill), use a soft plastic insert (I used, as you may guess, a 1/8in diameter insert) flush to the front of the bolt. Similiar to the ANS automag bolt that has a soft plastic insert instead of the foamie - Result = Ball stack is aligned, insert keeps balls from rolling back to far, letting next one enter chamber.
Solution #2 - Replace bolt with new one that does not have as deep a cup. For instance, in my case I used an R11 bolt that holds the chambered ball forward about 1mm, keeping the ball stack slightly more inline, enough to eliminate my chopping problems. This does not hold it as far forward as the homemade insert
Subset to both these solutions -
After doing both of these and experimenting with different depths of inserts into the stock bolt, and burning through over 1000 rounds using the stock and R11 bolt, I reduced the force the HALO put on the ball stack by adjusting the HALO DWELL on its mainboard. There is a small potentiometer on the board that has some dots on it. Using a small screwdriver, I adjusted the dwell to halfway between bottom (turning left) and the dot it is set on from the factory. I burned through another 1/2 case or so testing different dwell settings on the HALO finetuning it, before I put the board back in, but about 1/2 way seemed to work the best. In my opinion, the oiling of the belt does essentially the same work. It allows the belt to slip slightly, lowering the drive pressure on the ball stack, but ONLY at the limit of the drive spring. Before reaching the end of the travel on the drive spring, the pressure is determined by how wound that spring is (Use your finger to wind the drive cone, and you will see what I mean). I think what is happening in this case is the motor overruns the drive spring, applying force directly to the ball stack, and without increasing the slippage, the ball directly above the chamber is forced even farther in.
I ended up using the R11 bolt since it ended up keeping the ball stack in about the same alignment as my adjustable bolt face, and I do not like the venturi design, just personal preference.
Try this, put your halo on, fire it up, and look into the chamber from the front without the barrel on. You will see what I am taking about the ball rolling back into the bolt face and the next one coming down. Now use a revy or just drop two or three in, you'll see that the ball above the chamber does not protrude as far.
After extensive finetuning and investigation, I personally have never seen a case where MY halo forced it past the ball detent in MY marker. I ran about 500 cycles manually using the stock bolt without modification on my HALO to try and determine exactly where the problem was, and not once did it double feed FORWARD. Try leaving the breech open, ungas the marker, and put the bolt slightly in the chamber, with the pin engaging the ram. Now just cycle it by hand, no barrel, and see if you ever get it to double feed forward, I never did. Generally, I would assume that the rolling back is a function of the design of IR3 to use the COPS sensor, the breech may be a little larger, allowing the next ball in line to protrude a littl farther, letting the ball roll off of the COPS sensor, etc., but not having an Angel LCD to compare the breeches on I have no idea. I used my digital calipers to measure breech clearances, bolt length, ball cup depth, etc., but don't have the numbers here at work.
Since doing these two things, I have not had any trouble chopping whatsoever. The second I put in my stock, unmodified bolt, my IR3 turns into a blender, regardless of the dwell setting on the HALO. Since this setup, after about 4 cases, I have yet to use COPS at all, not feeding is just no longer an issue.
Your mileage may vary, but for what it is worth I am now a very happy Fly IR3 owner with a HALO B that has yet to chop, despite never using COPS. As for setting the dwell on the gun, I have absolutely no idea how or why that would influence ball chopping, other than increasing the dwell a couple of milliseconds may "pause" a ball in the HALO ballstack near its sensor just enough to keep the motor from overrunning the drive cone spring, but that just isn't very plausible to me.
Good luck and I hope this help
