I was thinking about the opportunity for flex too. That’s an awful long span to control flex. I would also be concerned about the clamping method slipping. Not knocking your setup, it is FAR above most home garage setups (ie hand drill and a coors light) but that would be my concerns from having some machinist background.
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Not sure I see how you guaranteed that the barrel was perfectly parallel with the table/vise and perpendicular to the axis of the end mill/quill. Nothing is referenced off or to the fixture. Looks like the barrel could be easily rotated in the vise unless you spent a lot of time indicating it in.
That’s not the point of the jig. But if I had more table you could use the jig to set up. The point of the jig is to align the FSB. Sure the key stock can flex a little but when it’s bolted down to the FSB it gets more rigid.
I don’t think the drilling will move it but you can set screw the FSB to prevent rotation. The reason for the 5/16 keystock is that’s what fits the FSB, its cheap and cheap to machine.
I just squared the barrel to the drill and lined up with the FSB by eye. No magic here. Theres a few ways to do this set up.
Thanks for the comments.
The Vltor drilling jig should be available in the next two weeks.
Very slick. I like both things you’ve designed.
I beefed up the FSB jig to minimize flex.
Not that I need one;), vary nice.
FWIW – I’m no machinist – I think the beefed up version is much better.
Quite the handyman.
It has no side to side movement which is what you want. The original with just the key stock worked fine but you needed to be careful. This one is not going to move.
If these go into production, they will look much better then my “machining”.
I may have the top plate waterjet cut to reduce machining costs as well. Onward!
Any chance of these becoming available?
tagged for updates.
I hope so. I’m hoping I can work something out with Rainier. Otherwise I’ll have to come up with something else. The issue is cost. To make just a few of them isn’t very cost effective but with a small demand its probably not going to be worth running a whole bunch of them.
Cost wise I’m hoping they can retail around $125 but thats yet to be determined.
Once they are a go I will update the post.
Thanks for the interest.
I could justify buying 1 at around that price point. Thanks for the effort you put into this.
Comp1911,
Any news on an ETA?
-RD62
you should have these on the market by now, man! whats the holdup?
what this about Vltor’s version? are there any pics.? come on, details please!
great job comp1911, I’m sure you’ll work out any bugs, it’s always fun and rewarding to come up with bigger and better ways to get 'er done!!!
Both appear in stock and ready to ship from Rainier Arms, which is where I got mine, and to the best of my knowledge is the only place to buy them from.
-RD62
those are both for the low pro gas blocks and will not work for the A2 frt sight bases.
Roger that. For the VLTOR low-pro gas blocks. The thread you quoted was from back in Feb. of this year. The low-pro are in production and shipping, as far as I know the FSB model jigs are not yet released, although I am waiting too! 
-RD62