This is the same SAR-1 mentiond in the previous post.

As the rifle heats. (And we are not talking about bump fireing, it was five shot aimed groups, then use another rifle then back to this one type shooting.)

The rifle begins to work very differently.

First, the bolt will only hold back if very hot, sometimes it will hold back if only very warm, but will close by itself once it cools a little.

Second, and the oddest problem, is the trigger. It is an RSA.  The screws are so tight I can not move them, and I can say that they are staying in place.  But as the rifle heats, the trigger pull becomes so heavy it can hardly be pulled.

I did start to notice a pattern.  The firts shot would always be heavy, the second would be fine, back to the way it is set in, then the next few shots would be heavy again with occasional light pulls.  Once the rifle is allowed to cool, the problem goes away.

Any ideas on this one guys?

First, the set screws are set in loctite and this is good. The bad part is that you need to make an adjustment and loosen these screws. You'll have to reread the adjustment process, or maybe Ken can chime in an give a pointer or two.

To make the adjustment easier, take your allen wrench and put it in the screw head. I usually try to move the screw to see how tight they are. If they are stressed to the point of fearing to strip, you can take a soldering iron and heat the allen wrench to soften the loctite. I usually put on a glove or hold the wrench with a piece of leather and apply pressure on the wrench while heating it up. When it gets to that "magic point", you'll start turning the screw and at that point, remove the heat and rotate the set screw out.

After I have removed them, I usually clean them and reapply loctite using a tooth pick on final adjustment.

Sounds like a walking hammer or trigger pin.

Nothing has changed within the trigger itsself.  It is just as it has been set.

The idea of the pins walking sounds like it could be the case, but upon my cleaning tonight I looked and they both seamed as tight as can be.

I'll re-install the RSA retainer plate, maybe it is not in correctly somehow.

I don't think this is a trigger problem, I think Heavy metal is onto something.

I don't think this is a trigger problem, I think Heavy metal is onto something.

That statement is self-contradictory and very confusing.

I don't think the set screws in the trigger are the problem.  I think that you are on to something with your idea of the pins somehow moving.

The previous statment was produced from lack of sleep which I now must remedy!

Thats better!

After a close inspection I found that the trigger pin has some vertical movement in it.  Not much, but I suspect that might be the problem.

I will take out the retainer plate and replace it with the origional shepherds hook.  That should put positive preasure on it downward and hopefully fix the problem.

 Ober

 Please let us know how this all turns out.  It is such an odd a interesting problem I can't wait to know the fix.

Check the fit of the gas cylinder: make sure the gas piston does not bind on it, also check the gas piston itself it should have a little slop on the carrier.

I have the grease on hand. I will do that along with re-instaling the shepherds hook.  I will let you know how it works out.

Thanks again.

I have removed the retainer plate and re-installed the  shepherds hook.

I have not had the chance to fire it yet, but all noticeable vertical play in the trigger pin is now gone.

I think with the moly, and small movement left should be much less noticeable.

As a note, the trigger pin would move up and down about 3mm.  very noticeable. It now has no movement I can tell.  I think this should help.

Looks like I have an extra reatiner plate for my Bulgy kit!