D56 sled adjustment troubleshooting question

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H

hunkaluv

Member
Oct 11, 2015
67
15
qc, Canada
Hi all,

I have a d56 .177 that's set up shooting 7.9's at 13fpe (12fpe vortek kit, but it's yielding 13fpe atm). It shoots really well, 5/8 groups at 55 yards off a rest. Occasionally however, maybe once every 30-40 shots, the sled doesn't function as intended and the action doesn't slide back when the shot is taken. The sled adjustment screws are currently set so that a slight bump on the butt will trigger the sled. If anything i'd say it's even on the light side, because sometimes when pointing the rifle upwards the sled will drop out of battery regardless of being bumped. WHy then would it not slide on a horizontal shot as it's supposed to? THe only thing I can think of is to polish the surface that the ball bearings slide on as I've seen done in other tunes. I've tried lubing with some light VFG oil, no change.

Any thoughts or suggestions?

Thanks in advance,

RYan
 
Hi Steve,

Thanks for the quick reply. I don't think there would be any Loctite there, at least none that I applied, and the rifle was purchased new last year. WIll confirm though. The stock screws are set at 30in/lb which is much higher than i'd like to go, but it's the bare minimum to stop the screws from rattling loose. Otherwise the stock screws would loosen up after 5 shots. And that includes adding a spring washer too. I'll also verify the rubber washer alignment. I did notice that the ball seems to have worn the slightest groove in the platform that it rides on (the one that you polished). I don't know if that would be good or bad.

Thanks again,

Ryan
 
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Sometimes it doesn't take much. Probably not your problem , but a few years ago I had a AA TX-200 MK111. I was shooting shot after shot , and then the rifle would not cock. Rather then force the issue , I took it back to Pomona Airguns , where I had bought it very lightly used. He removed the action , and caught under the spring was a hard plastic ball. Perhaps an airsoft BB ? It had kept the spring from fully compressing , and therefore cocking. I wouldn't have thought that was possible , but it worked fine thereafter. 
 
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Check the fin that your cocking lever pushes against to push the action into battery position. There's a metal bracket that is attached to the stock that has a fin that sticks up for the cocking lever to push against. This is what I mean:

On my D56, I found that that metal fin interferes with the sliding action making it rough and inconsistent. That's because that fin gets pinched between the cocking lever and the action when the cocking lever is returned to stowed position after cocking. Take a look and you should see what I mean. I tried posting my issue at GTA but everyone acted like they couldn't figure out what I was talking about: https://www.gatewaytoairguns.org/GTA/index.php?topic=166905.0 In the pictures, you can see a pic of that metal bracket after being removed from the rifle. You should be able to figure out what I'm talking about. That fin was actually galling the action a bit and the bare metal can be seen as a bright flash in the pictures. I even posted a pic of the flash with a red arrow pointing at it. After removing that bracket, the sliding action functions much more smoothly now. My shot groups tightened up a lot and I don't feel any recoil at all. People talk about feeling some recoil with their D56s but that's because of the fin.

After removing that bracket, you have to be sure to push the action forward into battery which you are already familiar with. BTW: you'll be able to tighten up that ball bearing a bit so that it doesn't slip out of battery so easily. Also, the groove that the ball bearing forms on the platform really doesn't make any difference in how it slides. That fin otoh really does affect things.

I understand why Diana put that fin there but you don't need it and it does interfere with the sliding action. If you remove it, please let us know how it works out for you. I'd like to know at least.
 
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Readerfisher9 - maybe dessicant beads? I can't imagine anyone would put a bb near a TX!

Mossonarock - great suggestion, I had a look and there seems to be no galling where the fin is. There's about 1mm of clearance along the length of the fin. How did you remove it? I assume the bottom bracket that it's attached to stays in place but you cut the fin part off?

Will definitely post when I have a solution for this issue. Headed out of country for vacay so I won't be able to dig deep until I return. 

Thanks for taking the time to reply!

Ryan
 
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The metal bracket is only for that fin. There's two screws that holds it to the stock. Just unscrew those screws and remove the bracket. Of course, you'll have to take the action off the stock first in order to get to those screws. Since its a non-permanent fix, you can always put the metal bracket back in. I definitely did not cut the fin off! I do not like doing things to my guns that are irreversible. This is a reversible fix. 
 
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Just a follow up for those who are interested. When I finally got a chance to do some work on the rifle, I found that the rear stock screw had come loose. Even though accuracy and POI hadn't changed, it was enough to cause the sled to bind, I think. I readjusted the sled, torqued the stock screws back to 30 inch pounds and was pleased to see that the rifle even kept it's original zero. I think the issue is probably the initial problem I had - the stock screws loosening up with time. I thought I had solved it with the spring washers and pushing the torque much higher than I would normally. I'd say that the binding problem probably happened after about 1000 shots. I'm reluctant to use Loctite on the stock screws but i'm open to other suggestions. Thanks again for all the replies and ideas.

RYan
 
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