So, for converting the 15-22 to a Delta Nut config - using standard A2 handguards, font post sight, etc...

What screw is suggested to attache the front handguard cap to the sight? Allen screw? Self tapping screw? Any particular size? I figure several have already done this and know, instead of me carrying the barrel into my local hardware store .

Look at this thread starting with post 14. I used a 1/4-20 x 3/8" socket head cap screw when I did my conversion 3 years ago New handguard?

I dont remember the exact size I used, but what I did was find a brass screw that was about the same diameter as the gas port hole at lowes, then matched it to a tap from my tap and die set and then tapped the hole.

Thanks guys, heading to the hardware store tomorrow after work. I got it all together in mock up mode, just need the last screw to be done...

I didn't bother with a tap. If you have a Dremel, slot down the length of the screw with a cutoff wheel. If you have the tap, super.

Just take the front sight into the store. Find a socket head cap screw that fits, like a 10-24 SHCS. It will pound into the gas tube hole with a little force.
You can tap the front sight if you want, then use some JB weld to keep it in place.
The head of the SHCS fits the 2 piece hand guards just right.
Be sure to put the hand guard end cap in place with the cup shape facing the corect way before you pound the screw in place.

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78staff, you probably won't see this post before you head out to the hardware store, but I tapped the hole and then used an M5 -0.8 screw. Here is a shortened quote of my post a while back.

Finally got by the hardware store and picked up a few pieces. The 1/4 x 20 was just slightly too large, so used 10-24 instead which worked great. Thanks all for the help...