[DCUNY]

Hello,
Relatively new forum member here.

I've searched high and low online for this info but can't find anything definitive.

The rear sight screw on my Truglo sight has the hex portion stripped / rounded out and I can't remove it with the wrench. I can drill it out but I don't know what exact specs on the screw are to replace it.

I did call Truglo and they "might" have some in stock and are going to ship me "something" but I'd like to get it fixed sooner rather than later. The hold time at Truglo was unbelievable and there were multiple times the reap asked "can I put you on hold for a while while I check something?".

Sights are Truglo TFO, model TG131GT1B
Rear sight has TG-H3 stamped on it.
Screw that is stripped out is 1/16 hex head. I'd be happy with a hex replacement or a straight thread screw if those are available to fit.

Any help would be greatly appreciated. Thank you in advance.

 

[SJ 40]

Can't say for sure but a good guess would be #. 2/56 or #. 4/40.

 

[Silver-Bolt]

If it is an SAE set screw the 1/16" hex key is for #3 & #4 set screws. Without seeing the screw I can't tell you the length or thread pitch. Drilling it out isn't going to be fun. The alloy used is heat treated to Rc45-53. Pick up a left hand drill bit. Before you drill, hit it with some heat. It is likely has Loctite holding it in place. You might get lucky and not have to drill.

 

[DCUNY]

Before you drill, hit it with some heat.

Thanks for this idea. What would be the best way to get heat on the screw? The only thing I can think of is a soldering iron, but the width of it may put it close to the edges of the part of the sight that the fiber runs through.

I bought a set of left-handed drills that also came with screw extractors. Would those be appropriate for this job?

Thanks again.

 

[Silver-Bolt]

Thanks for this idea. What would be the best way to get heat on the screw? The only thing I can think of is a soldering iron, but the width of it may put it close to the edges of the part of the sight that the fiber runs through.

I bought a set of left-handed drills that also came with screw extractors. Would those be appropriate for this job?

Thanks again.

I use a butane torch. Not knowing you exact site that may or may not work. The fiber rods should be easily replaceable it you happen to damage one.

 

[DCUNY]

Thanks to everyone for the help.

I wasn’t able to get any heat on it, but was able to get the set screw out with a minimum of damage to the threads using these:

https://www.thegrabitstore.com/products/alden-4507p-grabit-micro-broken-bolt-extractor-4-piece-kit

Started with the smallest and worked my way up in size.

Screw thread on the Truglo setscrew is 6-32 and the screw is 1/8 inches long. Ran a 6-32 tap through the sight threads to clean up the old metal and loctite.

Replaced the screw. If I loctite it again I will use purple this time instead of blue. Too easy to strip out those tiny 1/16 hex holes in the screw.

 

[HereticHulk]

Thanks to everyone for the help.

I wasn’t able to get any heat on it, but was able to get the set screw out with a minimum of damage to the threads using these:

https://www.thegrabitstore.com/products/alden-4507p-grabit-micro-broken-bolt-extractor-4-piece-kit

Started with the smallest and worked my way up in size.

Screw thread on the Truglo setscrew is 6-32 and the screw is 1/8 inches long. Ran a 6-32 tap through the sight threads to clean up the old metal and loctite.

Replaced the screw. If I loctite it again I will use purple this time instead of blue. Too easy to strip out those tiny 1/16 hex holes in the screw.

Where did you get the replacement set screw? I have a similar issue and need to replace it. Thanks!

 

[SJ 40]

Where did you get the replacement set screw? I have a similar issue and need to replace it. Thanks!

When I'm in need of set screws I visit my local Ace Hardware,they or at least my local one has carbon and stainless set screws both flat bottom,cupped and pointed.

 

[HereticHulk]

When I'm in need of set screws I visit my local Ace Hardware,they or at least my local one has carbon and stainless set screws both flat bottom,cupped and pointed.

I did that very thing and they only had a coarse threaded version. Apparently these set screws are fine threads.

 

[DCUNY]

Where did you get the replacement set screw? I have a similar issue and need to replace it. Thanks!

I got the screw at a store called Runnings. I was shocked they had it. Got both a hex and straight slot screw. Hex was 1/8 inch long. Straight slot was 3/16 long. I ended up using the slotted screw because it will be easier to remove in the future. I used purple locktight which is slightly less holding power than blue. Could have used a 1/8 long slotted but they didn’t have it.

 

[SJ 40]

I did that very thing and they only had a coarse threaded version. Apparently these set screws are fine threads.

Luckily my local Ace carries a wide variety and both fine & course.

 

[Diego Lainfiesta]

Hey, I run into the same problem. Here some recommendations:

1. DON'T use Loctite, the blue or red or any kind, you do not need it. You risk not being able to remove the screw.
2. The screw is a hex 1/16, is NOT decimal.
3. TruGlo uses a 6-40NF screw, they are National Fine threads.

How do I know it?

I left a screw in my rear sight and it wouldn't come out after using blue Loctite. I heated it, did not work. I drilled a very fine hole where the screw was (right in the middle) to remove the sight. Then I went to a machinist, to see if I could rescue the rear sight. We did, I had an additional set of sights from which we measured the rear sight, tapped the rear sight where the screw got caught in and everything was good afterwards. Hope it helps. I have been looking for the replacement screw, I had no luck.