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Posted: 4/19/2010 5:45:41 PM EDT
| Here is the deal. I bought a Colt HBAR upper/barrel at an auction awile back on the cheap end, which was probably due to the fact that the guy had tried to turn the A2 upper into an A3 with a raised weaver rail. The guy was a machinist for something like 30 years plus experience so he did a good job doing the conversion. I'm guessing he did this sometime back in the early 90's or at least pre 94. Anyway he machined the FSB down to a "low profile" look. Well I put it on my lower and it worked fine. Since then I have switched out the upper for a A3 Colt upper and was trying to switch out the low profile FSB to a standard FSB. Well I got one with the holes already drilled (probably a take off from another rifle) at a gun show and put it on the barrel. Went on fairly easy... but it seemed like one of the holes had been reamed out to much as one of the taper pins was sticking out the other side (almost half of it). This was only on one of the pins and there was no wiggle on the front sight. I put the rifle back together and it was short stroking to no surprise. I figured the alignment of the FSB and barrel etc, was out of wack so I put the "low profile" back on there and it worked fine with out issues. So my question is am I pretty much screwed out of having a regular front sight base using tapper pins, or can I use a non tapper pin gas block? On the non tapper in end what about a standard FSB with set screws? Thanks for the help! |
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First off, welcome to the Site!!!!!
Front sight bases are not unified drilled, but installed on a barrel one at a time, hence jigged correctly, then the taper pin channels are drilled one at a time per that barrel. If you try to use a already drilled FSB on another already drilled barrel, bank on the two not aligning correctly. The FSB is not a total lose, since you still have the option of attaching it with other methods. Being that the sides are already drilled on the FSB, you can install set screws if the channel are off enough to allow the set screws to bit into fresh barrel metal when correctly indexed. Another method that is bit more extreme is to use the bottom hole of the FSB for a single set screw, then use loctite to bond the FSB to the barrel. Lastly, if the channel are close to being correct for each other, the with the use of over sized taper pins, you can jig the FSB up correctly, then over drill both channels to make each other indexed, and secure the two with the over sized taper pins. |
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