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Discussion Starter #1
Hello,
I am having some trouble getting my 22 kit to run full auto in my HK 91.
German made HK 91, S&H sear with friction lever.
Using a semi-auto trigger pack it will function with most ammo. For some reason it does not like the Federal Auto Match.
When using the sear pack it has the usual problems of running for 3-4 rounds than stopping with a live round in the chamber. There has been only one ammo that has not had any hiccups and that was some older Winchester Power Point in the gray box. Time reference, price sticker $22 for a brick of 500 and that was high dollar ammo. Tried some new Win. Power Point and only got one or two rounds off before stopping.
I did searches and skimmed through the results and saw a mention of timing the trip but no other information was in the message.
I popped off the extractor and using a feeler gauge measured the distance between the bolt face and the chamber face when the trip sear would release the hammer. At .235 the trip sear did not release the hammer but anything less would. Also the tip of the trip lever was about 2/3 of the way up the incline of the wedge that moves the trip lever.
I will need to go out to the range to try and confirm what I think is happening. My SWAG is that when the bolt is moving forward and the wedge hits the trip lever it slows the bolt down so much that when the hammer is released by the trip sear it follows the bolt, hits the firing pin which has time to go forward and return under spring pressure before the bolt has fully chambered the round. Has anybody measured the gap between the bolt face and chamber when the trip sear releases the hammer? Is there a proper distance for timing the trip sear?
My thought on how to correct this is to slightly change the angle on the wedge so it might lessen the drag of pushing the trip lever, there by not slowing down the bolt as much and letting the hammer be released later. Has anybody tried this approach? If so what was the results?

TIA for any information that will help me get this rifle running because I have an AM 180 drum adapter that is not getting used until the rifle is working in full auto.

wcube2
 

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Mine was very sensitive to the ammo choice and not running dry.

I used CCI Mini-Mags and CLP on the moving parts.

As it was a RR gun, the pack also had a roller trip lever.

Dennis
 

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Having spent many hours, (really months) on this very topic, I do believe the actions of the trip lever to be somewhat of the culprit, but don't believe "grinding" the tip of it, may be the solution (especially if you have multiple hosts). I do believe the trip is involved because functioning is fine with semi-pack operations. What I have tried to do, based on numerous discussions with one of our supporting vendors, is to reduce the "effort" needed to trip the lever by "stretching" the elbow spring. I believe another issue to be the timing of my hammer and the fact that it rides "high" reducing the arc of movement. And I'm also running a burst pack which adds another dynamic to the mix.

The majority of my issues seem to involve "light" primer strikes and I have completely disassembled and cleaned the kit as well as experimented with adding more tension on the spring closing the bolt (jury is still out on that one-was trying to mitigate "bolt bounce" theory). Ammo can be touchy and CCI mini-mags seem to be the best. Right now I'm concentrating on my hammer angle and have gone the re-timed route but have not been able to conduct testing.

The great thing about embarking on this challenge is that it has become it's own little hobby (within another) AND I've mastered disassembly and more importantly assembly of my burst pack because of all the "tuning". In fact, I may just experiment with changing the angles on the trip as it could/would be dedicated to my .22LR host. (Already dedicated a housing because of other tweaking issues.)

Another thing of note is that with full magazines, I get hiccups but down around the 10 mark it will "dump" in FA. Haven't figured out the disassembly process of them:)

I also have a drum adaptor and am working towards that end. Maybe next year....
 

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Discussion Starter #4
Forgot to add trigger pack has a retimed hammer.
I did try using CCI Mini Mags but it still would have a hiccup every once in awhile.
The wedge I was talking about changing the angle of is the part of the 22 bolt that hangs down from the back end and is what pushes down on the trip sear lever.

wcube2
 
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