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Posted: 3/4/2008 1:28:09 PM EDT
| Hi- I'm new to the board here. I have always bought barrel assemblies, but I just bought an 18" WOA SS SPR barrel. It is a bare barrel and I need to put a front sight base on it. Just a normal forged non f-marked fsb. They havent delivered the barrel yet, but it is supposed to have dimples on it. What does that mean? I know I won't be using taper pins, but I can't find any other types of fsb. Thanks for any help offered. |
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I think they are saying you can use a set screw type front sight base.. the dimples are on the bottom for your gas block / front sight base if you want the front sight base you can buy a non-drilled one and have it drilled and tapped for your barrel brownells has them .  The vltor gas block i purchased had two set screws the barrel had one dimple on the underside to mate up with the gas block  You can also see the dimple on my SPR build however the dimple is not used with my clamp on sight but it does help aligning it.   Welcome by the way  |
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Thanks for the quick reply. I've been looking around some more and found a couple of things. Here is a pic from White Oak's site: http://www.whiteoakprecision.com/images/upper_frontsight.jpg This one has at least two set screws. A dimple opposite the gas hole makes sense with this setup. But on the retail side of the White Oak website they show barrels with 4 set screws. Aha- you've got the same SPR barrel I ordered- I am starting to understand now. Now I just have to find a vendor that carries a fsb with the set screw on the bottom. I guess I can make my own- if no one carries it. I sent WOA an email to see what they say. |
| I think the FSB in the White Oak picture you posted is what is sometimes called a DMR sight. It doesn't mount using taper pins or the dimple on the bottom but require four additional cuts, two on either side of the barrel allowing you to fine tune your front sight for using the opposing set screws. I have a White Oak SPR barrel waiting for my next build, and it has the dimple directly opposite the gas port for aligning a low profile gas block that usually fits under a rail and typically has no provision for a front sight. I've never heard of a standard style FSB that mounts using set screws from the bottom. The PRI sight pictured in the second post clamps from right to left, and is an excellent choice. You could also check out the clamp on FSB's from Yankee Hill. Another option, the one I intend to choose, would be to use a lo-profile gas block under a 13.5" forearm like the one from Troy or Larue, and add a folding front sight on top of the forearm. |
| You don't "need" a special fsb for an SPR barrel, but since SPR type rifles usually do not have fixed front sights, the barrels are not usually sold w/ FSB's, or provisions to mount one. They usually have a dimple for aligning/mounting a low profile gas block, or you can self align a clamp on gas block w/ folding front sight as shown above w/ a PRI gas block. |
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Lots of great info so far. I went ahead and bought the cmmg fsb with the 4 set screws. Can I just tighten the the set screws against the barrel or does the barrel need matching flats machined on it? http://www272.pair.com/stevewag/artube/arbarrelflats.JPG Like this? Hopefully I can get away without the machine work... |
| I don't know one way or the other whether that will work w/o the flats. Try emailing John at White Oak Armament [email protected]. He should be able to help you out either way. |
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