.750 sight on a .700 barrel - how would you do it?

[Robb]

Anyone ever mount a front site to the barrel that had a size mismatch? .750 ID barrel mounted flip up front sight and .700 OD barrel.

Seems like there should be some pre-made shims available, but I can't locate any. I've been thinking about attempting to make my own out of tubing. Copper or brass maybe.
Anyone have any insight? Certainly this has been done before and I'm making this harder than it needs to be.

FYI: gas block is way under the rail, the rail is long and I would prefer a sight mounted to the barrel to compensate for rail flex. (Plus it's a little different and think I like the look... there I said it.)

Thanks for any insight.

[Great-Kazoo]

Get it knurled. Buy a .625 and have it reamed to fit, OR some shims from brownells, i have some if you want to drop by. Only concern with shims is possible gas blow-by

http://www.brownells.com/gunsmith-tools-supplies/sight-scope-installation-tools/scope-shims/kit-no-af-12-steel-shim-stock-prod25974.aspx

following thicknesses: .001", .0015", .002", .003", .004", .005", .006", .007", .008", .010", .012", .015".

[ray1970]

I had Bert do one for me. Just had him turn the front part of the barrel down and used the .625 front sight assembly. I have pictures but it will be tonight before I can post them up.

[Robb]

Kazoo, gas blow-by is a non issue as I'll have a gas block further back. And I wasn't thinking of flat shim stock, thanks for pointing that out, that should work.
Ray, hate to turn the barrel down at this point, it's melonited and all pretty. But it's an option and options are good.
And why did the barrel get turned down instead of boring or reaming out the front sight?

[thvigil11]

If its a clamp on sight, you could remove material from between the clamps to get it to snug up tighter.

[ray1970]

Ray, hate to turn the barrel down at this point, it's melonited and all pretty. But it's an option and options are good.
And why did the barrel get turned down instead of boring or reaming out the front sight?

That's just how I wanted it done. Bert parkerized it all when he was done. I basically took a standard mid gas barrel and made a dissipator type setup.

I'll toss up some pictured this evening. It really turned out great.

If you reamed out the sight base it might work. Just not sure how much meat would be left. I had Bert properly install mine with taper pins.

[Robb]

Thanks guys, I'm going to pursue the shim route for now, and we'll see if it works out.

[ray1970]

Here is the job Bert did for me. He chopped the original mid length FSB and turned the front of the barrel down and pinned the .625 FSB on for me at the rifle position.

http://i102.photobucket.com/albums/m98/rjs1970/utf-8BSU1HLTIwMTIwMzAzLTAwMjIyLmpwZw.jpg

[ray1970]

Turned out like this by the time I was done.

http://i102.photobucket.com/albums/m98/rjs1970/utf-8BSU1HLTIwMTIwMzI3LTAwMjcyLmpwZw.jpg

[ray1970]

With the FSB and gas block (old FSB) both properly taper pinned, no worries about anything coming loose or moving out of position.

[BPTactical]

And why did the barrel get turned down instead of boring or reaming out the front sight?

Ream the barrel bore on a .635 FSB to .700 and the band's will be too thin.