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1/25/2018 7:38:29 AM
Posted: 12/6/2002 3:35:34 AM EST
Does anyone out there have a pic of the front sight base jig/fixture used to drill/ream the front sight base taper pin holes???

I'm installing a flip-up front sight on my DPMS 16" barrel; I'll be using a mill and making my own fixture to align the existing barrel holes with the undrilled sight base...(using oversize pins & taper reamer)...

But I'm curious as to what the 3rd echelon armorers use to hold the parts in position while they drill & ream the holes...
Link Posted: 12/8/2002 11:51:09 AM EST
...Hmmmm...No armorers here...Or they don't have digi-cameras...(or not talking)... OK; here's my current thought: Using a 1/8" drill rod to align the stripped bbl in a bbl vise, in a machinists vise, in the mill. Remove the rod, replace with center drill. Slide flip-up FS/gas block and handguard cap onto bbl. Use machinists level to level gas block/FS. Clamp gas block lengthwise to bbl vise. Center drill the gas block, followed by 1/8" drill through to bbl hole. At this point I'm undecided whether to try drilling straight through other side, or flip the whole thing over & repeat. It takes longer; but that's probably what I'll do... I've replaced FS/gas blocks before, and have found that a # 3/0 taper reamer is not enough to get a good smooth taper (production holes I've seen are really rough); I usually finish up with a # 2/0 reamer and longer pins (milled in place to proper length). Just thinking out loud...
Link Posted: 12/10/2002 1:55:13 AM EST
If you can mill flats on the barrel, tap the sight base and make it windage adjustable. -Ray
Link Posted: 12/10/2002 1:02:54 PM EST
Originally Posted By ray-vin: If you can mill flats on the barrel, tap the sight base and make it windage adjustable. -Ray
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...Hmmmm...A setscrew on each side of the sight? Pressing on a flat on the bottom of the barrel (each side)???... The idea being to "rock" the sight sideways with the setscrews to center the front sight blade??? Without touching the rear sight (i.e.: leave it centered)??? Interesting idea...
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