Hammerli AP20 Bolt Closing Adjustment
Posted: Wed Oct 18, 2023 4:04 pm
The college team I help coach bought twenty six AP20's in 2019 that we use to get students started. Other than a few initial problems, they have been very reliable.
We've started up again this fall, and a minor issue I've noticed in the past appears to be spreading and getting worse. On most of the pistols, when you lower the cocking lever, there it a bit of resistance as you close it, and then the cocking lever snaps down into place. It feels consistent with a toggle linkage going "over center", but mechanically, that's not the way it works. I don't have one in front of me, but the diagram shows a small shelf in the slot of the cocking lever that might provide that last little "step" in closing force. The resistance may be the O-ring on the bolt seating in the breech.
It may just be that we haven't kept that slot adequately lubricated, and the "step" has worn. Most of the time, the cocking lever will pop up just a little bit on firing, but it doesn't seem to affect anything. A few days ago, I heard a weak report from one pistol, and when I looked, the cocking lever was up by over an inch. I suspect it had opened up enough on firing that some of the pressure had vented out the breech. It may just be that the student didn't close it all the way, because I caught them doing later later on.
It doesn't appear that there is any way to adjust something to fix this. Unless I'm missing something, the only real cure appears to be to replace the cocking levers, which will be costly in time & dollars. Another possibility is that the bolt O-rings are getting worn. Those look even more involved to replace...
Has anyone else run into this, and is there a simple fix? I'm definitely going to grease the lever slots tomorrow when I'm at the range.
Thanks!
We've started up again this fall, and a minor issue I've noticed in the past appears to be spreading and getting worse. On most of the pistols, when you lower the cocking lever, there it a bit of resistance as you close it, and then the cocking lever snaps down into place. It feels consistent with a toggle linkage going "over center", but mechanically, that's not the way it works. I don't have one in front of me, but the diagram shows a small shelf in the slot of the cocking lever that might provide that last little "step" in closing force. The resistance may be the O-ring on the bolt seating in the breech.
It may just be that we haven't kept that slot adequately lubricated, and the "step" has worn. Most of the time, the cocking lever will pop up just a little bit on firing, but it doesn't seem to affect anything. A few days ago, I heard a weak report from one pistol, and when I looked, the cocking lever was up by over an inch. I suspect it had opened up enough on firing that some of the pressure had vented out the breech. It may just be that the student didn't close it all the way, because I caught them doing later later on.
It doesn't appear that there is any way to adjust something to fix this. Unless I'm missing something, the only real cure appears to be to replace the cocking levers, which will be costly in time & dollars. Another possibility is that the bolt O-rings are getting worn. Those look even more involved to replace...
Has anyone else run into this, and is there a simple fix? I'm definitely going to grease the lever slots tomorrow when I'm at the range.
Thanks!