Comments on: Beggs Devises Indexing System for Centerfire Barrels

By: Reloading supplies

Reloading supplies — Thu, 11 Jun 2009 21:26:31 +0000

This: “Think of a slot-head machine screw being tightened till it bottoms. The final orientation of the slot after tightening depends on where it picks up the first thread of the threaded hole. If the hole itself is rotated then the final position of the slot, relative to the viewer, will be rotated by a similar amount. Screw a slot-head machine screw all the way into a nut. Now turn the nut. The slot rotates with it.” really helps people see what’s going on!

By: bluetentacle

bluetentacle — Tue, 21 Oct 2008 05:46:48 +0000

An AR-15 barrel bushing has no threads and has a hard shoulder. If you remove the indexing pin (necessary because of the gas tube, which is not applicable for a bolt-action) the barrel can rotate any which way without changing the headspace.

By: Mike

Mike — Tue, 21 Oct 2008 04:07:11 +0000

The threaded bushing that Mr. Beggs is calling it is hardly new. It appeared in the 19 May 2007 column of barrel indexing in the Rimfire Benchrest portion of the Benchrest Central Forums. Here is the link:

http://www.benchrest.com/forums/showthread.php?t=42418&highlight=index&page=3

The author “Vibe” describes the process very well.

What surprised me the most about this particular idea is the fact that it didn’t gain any traction on the forum. I’m glad Mr. Beggs picked up on it because I think it has real value. I agree with bluetentacle and don’t think this is the most elegant solution either. For that – read Vaughn’s book. That man was way out in front of the rest of us.

By: Josh

Josh — Mon, 20 Oct 2008 18:16:23 +0000

I’m sure this will alter the barrel position on the action without changing headspace, as described – it’s an offshoot of the familiar commercial Helicoil thread insert. Question is, does this do any good? Where’s the data?

By: bluetentacle

bluetentacle — Mon, 20 Oct 2008 05:53:52 +0000

It seems to me that an AR-style barrel bushing/nut design would be a MUCH more elegant solution to this problem.

Editor: Beggs contemplated using a Savage-style barrel nut (rather than conventional shoulder). Problem is that the chamber still moves toward the bolt face as you screw the barrel in. Thus headspace is not constant as the barrel is rotated to different, indexed positions.

By: Phil H

Phil H — Mon, 20 Oct 2008 00:33:41 +0000

That’s the best technical article I have read in a while.

Martin, the set screw will not necessarily damage the threads. An old machinist’s trick is to place a soft lead shot between the set screw and the shank threads. This will actually provide more friction that the set screw alone while protecting the shank threads.

I would like to see pictures of the bolt and breech.

..Phil

By: martin

martin — Sun, 19 Oct 2008 23:28:07 +0000

This makes no sense to have a threaded bushing with a setscrew to hold it in place it will cant the insert off center,the setscrew will damage the threads in the reciver what are you thinking.