How do we tighten up the rear sight elevation adj screw?

[davee1]

So to those that have been following the P17 discoveries...well here's one fresh outta my hat. Both of my P17 rear sight elevation adustment screws are quite loose, while the windage screws are excellent. They are so loose in fact, that they tend to loosen up with firing of the pistol, effectively raising the elevation. The sight is just a simple design...A screw threads into a nut held in place by a hex mold in the plastic housing, and turning the screw raises or lowers the sight. I'm not sure that using a lite threadlock compound is the right thing to do. If it was, what color do we use...green? Is there a different way, like using a stiffer sightspring, thereby putting more pressure on the screw to keep it tight? Those springs are really small, smaller in OD and length than a ballpoint pen spring, and hard to find, and hard to find such a small spring that would put more pressure on the adj screw, because such small springs really are limited in the amount of pressure that they can provide...Unless you can increase the length and/or OD of the spring, but both the spring length and OD are limited by the springseat holes in the rear sight.

What about using one of those nuts that have the white locking material in them? I think they are called locknuts or NyLocks because of the nylon insert. They are available at Macmaster Carr. The original nut is easy to replace with one of these Nylocks. I think I'm going to invest in a few of those puppies....

What do you guys think? I can't have my P17s gradually shooting high with use!!!

davee1 - 9/4/2007  3:49 AM

What about using one of those nuts that have the white locking material in them?  I think they are called locknuts or NyLocks because of the nylon insert.  They are available at Macmaster Carr.  The original nut is easy to replace with one of these Nylocks.  I think I'm going to invest in a few of those puppies.... What do you guys think?  I can't have my P17s gradually shooting high with use!!! 

Dave, I've used Nyloc-type nuts in several non-airgun related applications, though most of them were larger. I'd make a wild a** guess that if you can find one in the proper thread that fits the receptacle, it'll work pretty well in that application. It's not like the screw would be routinely adjusted once you have the thing sighted in, so the nylon thread-gripping component should last a long time. Loc-Tite might work, but I'd be concerned that it would only be good for a few turns before it might lose its grip (others with more experience please chime in).

You might try a local hobby store that caters to R/C planes and cars to see if they carry small Nyloc type nuts, if there's one in your area. And sometimes the hardware section of the big box home improvement stores like Lowes or Home Depot have a section with specialty hardware that might include Nylocs.

Bryan

[davee1]

I ordered some M4x.7 nylocs from McmasterCarr being the guy who dont wanna leave the house. I used a thread gage and dial caliper to determine size. Its either M4x.7 or 8-36. Now,I dont see8-36 anywhere...although it is a real size, just not used much I guess. 8-32 is much more common, but that wont work. The good thing is that McmasterCarr shipments come to me the next day because their in California. So I'll know tommorrow.

[davee1]

The NyLocks dont work because the locking part of the nut is too far down into the nut for the screw to seat into. The sweet spot of the sight is above the nylon in other words. If I flip the nut over, so the locking part is at the top, it's impossible to thread the screw in. So then I thought "well, I'll use a longer screw". Nope. A longer screw has a head diameter that is bigger than the original, and wont fit into the counterbore of the sight, so the screw head sticks up into the sightnotch. I'd have to machine in a new counterbore to accomodate a standard metric M4x.7 screw. The stock screw has a custom head diameter which is not available...it's about 6mm. The standard screws head diameters are 7 & 8 mm depending on if you want to use philips or slotted head.

I'm afraid I'm back to usinggreen locktight or some other color to make the sightscrew stay in the position that I need it to.

[davee1]

Please...join the fight...soldiers are needed badly...Yep, the spring is really small, so not a lot of force is produced. And a larger stronger spring cant be used without modifying the sight and receiver, because the spring has seat holes in the sight and reciever that are very small and shallow. The easiest way I can think of right now is just to use lite threadlocker, since my brilliant idea of using a NyLock nut was utterly and completely decimated. I hate it when the guns win.

Use some silicone gasket cement or silicone bathroom crack sealer. Apply some to the threads of the screw and smooth it off. Allow to dry and screw in. the rubbery surface in the threads will allow it to be adjusted but stops it from vibrating out.

[davee1]

Excellent idea!!! Thanks!!! Thats a winner. Easy to do, cheap, and easily repeatable if needed. Aint this a great place to be? Where else are we gonna get ideas like this? And lets not forget that the idea came from down unda.

Andre's idea sounds like a great way to go. Again, since the screw isn't in constant use, it should keep the screw in place pretty well.

Just a question though, Dave; how easy would it be to take one of the longer screws with the too-large-diameter head and turn the head down to the right size? I'm just wondering if it could be done with a drill or drill press (or lathe if you happened to have one), and a file if you can figure some way to chuck the screw in without buggerin' up the threads.

Personally though, I think I'd go with Andre's suggestion ;~)

Bryan

[davee1]

Bryan, I could do that, I mean chuck up the head and turn it down but I was looking for somethingthat I didn't want to go to too much trouble over. And if the solution was simple enough then anybody who experiences the problem could do the simple mod and be done with it. I'm thinkin Andre's suggestion is a good one too.