I’ve seen it mentioned a few times in passing on the forum and else where. There is a youtube video of a Noveske shop tour where they mention fitting bolts to barrels. Grant from G&R mentioned it in his varmit rifle build thread. Can someone advise what this entails and how it is accomplished.
Thanks for any info.
Irrelevant info, ignore this post
Gotcha. But all bolts are not going to give the same headspace reading. For instance I sent my noveske upper in for a feeding issue later id’d as a weak buffer spring. I sent in my BCM bolt that I bought as a replacement/spare. The guy with Noveske said that the BCM bolt barely passed headspacing on the loose end and the Noveske bolt was tighter and would provide better accuracy.
So what does fitting require. Going through a box of bolts finding one that fits tighter on a particular barrel? Is the bolt lapped into the barrel extension?
You got it. There is no lapping done and there’s nothing an end user can do to fit a bolt to a barrel other than what you’ve mentioned.
Thank you Eric D.
So is the following correct?
-The headspace is set when the barrel is installed in the upper receiver.
-Any bolt that is in spec will operate in a correctly built/assembled rifle
-There is a small but acutal bennifit from choosing a bolt that is in spec but at the tighter end of the spec and in theory should have a longer functioning life and/or provide better accuracy vs a looser fitting bolt.
Is anyone able to discuss the acutal bennifit in accuracy provided by a “fit bolt”.
What would be the proper gauge to measure this and how would you employ it?
This has nothing to do with fitting a bolt to a barrel.
C4
Noveske came up with a standard fitting for bolt to barrel. We purchased gauges from them and follow their protocol when fitting.
To date, every single gun that I have fitted a bolt to a barrel has shot UNDER 1" groups.
Do I think it makes a HUGE difference? No I don’t. It is one of the steps that I follow religiously though when building a precision rig and to date, have never been let down.
C4
The “fitting” is just a smaller than MIL-SPEC headspace range that we keep. It’s mainly done by controlling headspace very precisely when making barrels, then checking headspace during assembly with gauges that have a smaller window between Go and No-Go that M16/M4 standards.
So what you’re saying is, I’m SOL!
serpico1985;
The headspace is set when the barrel extension is screwed onto the barrel, not when the barrel is installed in the receiver.
Any “settling in” that happens when the rifle is fired is simply the tooling marks on the bolt and barrel extension being hammered together/peened smoother due to case pressure and the rubbing of unlocking.
Unless the machinists involved were drunk or incompetent, those toolmarks will be less than tenth of a thousandth. If you had a rack of headspace gauges, each half-a-thou apart, you might (might) be able to measure the change.
Grant assembled a Noveske N4 barrel, LMT bolt riding in a VIS years ago for me and it’s an absolute laser.
Thank you Grant and Todd.K for clearing that up!
How about Chrome Lined barrels?
The last one I did shot .85 groups and was a 10.5 barrel.
C4
That’s impressive.
Grant, how much of a difference have you noticed in groups between precision rigs with matched barrel/bolt and non matched barrel/bolt if all other parts are equal?
I don’t know that I have ever compared two guns at the same time (one with a fitted bolt and one without). For me, it is a pure crap shoot as to what you get with a non-fitted bolt. Could be awesome or could be 2-3" groups.
A fitted bolt is just ONE part of a quality build. There are other aspects that go into it as well.
C4
I understand its just one part. I was just curious because I’ve put a precision rig together with match barrel SSA-E trigger etc. the one area I skipped was the fitted bolt. I tried to read a bunch about it and it seemed most people thought it wasn’t necessary. Interesting to hear you say a non fitted bolt could open groups that much. I haven’t had a chance to shoot my rifle yet as the trigger is in the mail. Hope I got lucky with the non fitted bolt. Thanks for your input.
Gotcha, removed the post.