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: my brain all the way around it. I'm putting my gun back together now, just got done being "hacked on" again, thanks Dark Horse, you amaze me. So I'll try to fully comprehend, thanks for the insight Vamp. : Razor : : No, how far the backblock moves is strictly based on the stroke of the ram (unless you crank the IVG in so far that you bottom out the mainspring on the cocking.) : : Now about shortstroke and chop and feedrates... : : You want the bolt to clear the feed tube as much as possible before hitting the uncocked cocking knob. Before the backblock picks up the hammer and mainspring, the bolt is the only other thing moving. The ram can move this extremely fast. The hammer adds mass and the main spring adds force that constantly increases as it compresses, slowing the rearward travel of the bolt. The faster you can get the entire feedport open the faster the ball can feed. It has been proven that a 1 1/4" stroke ram has better feed rates because the bolt is 1/4" more open before picking up the hammer. (Note: this mod usually requires you to find a longer cocking rod, perhaps even scratch built.) Now you don't want the cocking rod so long that there isn't enough room between the sear and lug for the sear to fully come up (will fail to cock.) or too long - which causes excess wear due to the hammering, or may even skip over the sear from the impact. In general you want it to pull the lug an additional 3/32-1/8" beyond the sear/ lug contact point. As far as the bolt is concerned, the further it goes back the better. If it can go a long ways back beyond the feed tube, on a short stroke, it may still properly feed. Chops will be reduced because there is more effective open time. Without additional force on the ball, a ball needs to be about 87% of the way into the breech when the bolt hits it. (This is the point wherethe force applied by the bolt is equally forcing the ball down and forward into the feed neck which would cause a chop.) this takes roughly : : 55mS ignoring friction and assuming no additional downward acceleration is applied to the ball (Verticle feed.) This time is figured from the time the bolt clears the centerline of the ball and assumes that the bolt is moving fast enough to not interfere with the downward fall of the ball... So as stated- the later in the bolt opening that the backblock hits the cocking knob,thus rapidly slowing down, the better. : : : How far back the bolt/block travels is totally controlled by the length of the cocking rod. If you shorten it too much you will not even catch the sear. My timing practices were gleaned from Ravi Chopra's web site, check it out it may help you. If you see you bolt in the feed tube in the natural state, you short stroke the trigger you miss the ball, or worst case you partially load the ball and chop (if you don't have the front reg set correctly, if it is set correct and you short stroke the bolt will stop on the ball rather than chop through it). If you don't see the bolt in the natural state and you short stroke, there is that extra margin for error 1-2mm that can save your butt. Just try it out and see if it helps, you can always go back to how you have it now. Seeing is believing. : : : Razor : : : : : : : : Tighten down you cocking rod in the marker and use a wrench like Vampyr said, loosen the set screw, and then back the nut off a little and cock the bolt back and see where that leaves it, can you see the tip of the bolt? If so it's not far enough, keep going but don't go further than about 1mm back from the feed tube. Then using the wrench to hold it again and tighten the set screw, and your done. Hope it helps. : : : : : Razor : : : : on mine, the bolt shows when i cock the back block at resting position, but when gassed up, it moves all the way back, until the bolt clears the breech. Somebody explain to me if im wrong, but wouldnt it be less of a shortstroke possibility if the cocking rod is shorter, because it would be cocked sooner in the back stroke in case of a shortstroke? when set like you guys suggest, it cocks at the very last portion of the backstroke, thereby increasing the chance of missing the lug? please tell me if im wrong, i need to adjust it ifi am. : : : : jeff