A_Med Posted April 25, 2009 Share Posted April 25, 2009 I'm updating a rifle for 3-Gun and I took off the old railed Gas Block to replace with a low profile. The railed Gas Block was of the clamp on type with 3 Bolts along the bottom. I would like to replace it with a model that has 3 Set Screws instead. I remember reading somewhere that with the set screw type you need to do some gunsmithing to add Divots on the barrel. Anybody have any experience with this and is it truly necessary? Thanks. Angel Link to comment Share on other sites More sharing options...
ken hebert Posted April 25, 2009 Share Posted April 25, 2009 (edited) Not absolutely, totally necessary, but not a bad idea. I have put together several uppers for myself without the flat under the screws and all function properly. In fact, my original rifle that I have been using for either 3 or 4 seasons now has a set screw gas block and I know it is just tightened to the radius of the underside of the barrel. YMMV. Edited April 25, 2009 by ken hebert Link to comment Share on other sites More sharing options...
kurtm Posted April 25, 2009 Share Posted April 25, 2009 I must disagree with My friend Ken A-Bear, YES the divit is absolutely nesseccary. If youy don't on a high round count stage your gas block can and will drift forward creating the "Manually operated AR-15". Mike Voigt has had this happen, as has Eric Miller, Jimmy Holdsworth and several other 3-gunner I know. YES I have seen it person. Now you don't need to do all 3 just one of them and it is real easy. Put on the gas block, check for full flow, screw it down nice and tight, take out one of the screws and run a drill bit in the size of the hole to mark center. Remove the gas block and drill a nice little divit just a little deeper than the shoulder of the drill bit...so it looks like a slight cone shaped divit. Re-install the gas block...check for flow and then red lock-tite the whole mess down, or use rock-set which is less heat sensitive. KurtM Link to comment Share on other sites More sharing options...
PacMan Posted April 25, 2009 Share Posted April 25, 2009 (edited) Like Kurt said, mark and drill. Another way to do it is use a round file and make a very, very, very shallow cut across at the same spot, just enough to allow the tip of the set screw to bite into the barrel. I used the manual filing method because I am not very good with a drill, I always have this fear of making a secondary gas hole Edited April 25, 2009 by PacMan Link to comment Share on other sites More sharing options...
Derek45 Posted April 25, 2009 Share Posted April 25, 2009 This happened to me in a class last year. My rifle has been very reliable for a long time, but my gas tube slipped forward enough to kill it. A friend had been telling me to come down and try his dimple tool, I ignored him, and this was the result. I used another AR for the remainder of the class, got home and fixed them both. I used a drill press with an X-Y vice, and locktite. Link to comment Share on other sites More sharing options...
GentlemanJim Posted April 25, 2009 Share Posted April 25, 2009 I prefer the clamp style over set screws..both can slip if setup too loose. No doubt making a recess for one or more of the screws will reduce if not stop slippage Its also best to make a witness mark on both barrel and block...then you can tell at a glance if they are aligned properly. Jim Link to comment Share on other sites More sharing options...
A_Med Posted April 25, 2009 Author Share Posted April 25, 2009 This happened to me in a class last year.My rifle has been very reliable for a long time, but my gas tube slipped forward enough to kill it. A friend had been telling me to come down and try his dimple tool, I ignored him, and this was the result. I used another AR for the remainder of the class, got home and fixed them both. I used a drill press with an X-Y vice, and locktite. There is no better Firearms Related Forum in the Free World. Thanks for the feedback guys. Great Stuff. Angel Link to comment Share on other sites More sharing options...
Derek45 Posted April 25, 2009 Share Posted April 25, 2009 http://www.rainierarms.com/?page=shop/deta...product_id=1089 Link to comment Share on other sites More sharing options...
ERIC Posted April 25, 2009 Share Posted April 25, 2009 I do it to all my gas blocks that are secured with set screws and use the method recommended by Kurt. It's pretty easy and you don't need a gunsmith for that. If you can't do it yourself or find someone to do it, get a low profile gas block that clamps down. Daniel Defense, Vltor and Stag are a few companies that make them. Link to comment Share on other sites More sharing options...
ken hebert Posted April 27, 2009 Share Posted April 27, 2009 (edited) Crap. Now you all got me paranoid. My #1 gun has been 100% up till now, I can just bet that it will malf since I've read this thread... Kurt, you suck. May all your kids be born naked. Edited April 27, 2009 by ken hebert Link to comment Share on other sites More sharing options...
Dan Sierpina Posted April 28, 2009 Share Posted April 28, 2009 Crap. Now you all got me paranoid. My #1 gun has been 100% up till now, I can just bet that it will malf since I've read this thread... Ken, Get some Loctite 290, it's a wicking grade, for assembled parts. Put a drop or two on the lower area of the gas block, it sucks in, and keeps things where they should be. Link to comment Share on other sites More sharing options...
kurtm Posted April 28, 2009 Share Posted April 28, 2009 Unfortunatly, it is quite easy to warm a barrel up past the point of "Grren Loc-Tite" melting. J.P. uses red Loc-Tite on their assemblies and still without the divit they have been known to walk out the front. I still feel that a mechanical way of holding the gas blok is best instead of clamping force or glues. BTW I have never had the red Loc-Tite come out of the set screws holding the gas block on, maybe because heat rises? I don't know but the screws seem to hold well enough if one of them goes into a divit. KurtM Link to comment Share on other sites More sharing options...
Sterling White Posted April 28, 2009 Share Posted April 28, 2009 Kurt admits to never having a loose screw.... Link to comment Share on other sites More sharing options...
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