Bedding question for the resident gunsmith's--barrel channel

[Macintosh]

Question especially for those with significant experience or training in this in hopes of getting some hard info rather than "I've always been told...", "it's what I've always done", etc. In my case I am referring to a tikka, although it may not matter the rifle in general.

I have always been told that when bedding a rifle you should bed a short section of the barrel. This is what I have done on the handful of rifles I've bedded myself, is bedded about 1/2" of the barrel in front of the action (not sure that distance is "correct", but it has worked well enough). However, with chassis being very popular for several of the LR rifle games, I'm curious about the importance and function of bedding the barrel like this, since none of the chassis I am aware of have any support for the barrel whatsoever. What exactly is the function provided by bedding the barrel channel? If those chassis are "good", then why bed the barrel at all on a bedded stock? Is it incrementally better, or is there some other reason to do it? Any insight is very much appreciated--thanks!

 

[sndmn11]

However, with chassis being very popular for several of the LR rifle games, I'm curious about the importance and function of bedding the barrel like this, since none of the chassis I am aware of have any support for the barrel whatsoever.

This reason is why the last four I have done all have 5 layers of tape clearance for the whole barrel to the action.

No clue what is "right" but I haven't found it to be "wrong" via crap results yet.

 

[WeiserBucks]

I've done a bunch both ways and never seen a difference.

 

[Macintosh]

This one is a pretty entertaining read. https://forum.accurateshooter.com/threads/bedding-under-the-shank-of-a-barrel.3868709/page-2

Still curious if anyone else has solid insight on this. Im leaning toward staying away from the barrel entirely at this point.

 

[ResearchinStuff]

That other thread is hilarious, sometimes an engineer's best job security is morons who have the same job title. In case there's any confusion, steel expands when its heated.

Anyhow, I'm curious to see what others think about this, I have bedded the first inch or so of my tikkas but the Drexel is always handy.

 

[Wrench]

I run 20 mil tape on stiff stock barrel channels. If they're flexing, I give it 40.

 

[Macintosh]

I run 20 mil tape on stiff stock barrel channels. If they're flexing, I give it 40.

I was hoping you would weigh in thank you. So you don’t bed with any contact under the barrel at all, is that correct? Do you happen to know why so many people bed under the barrel?

 

[dieselchessy]

I bed under the shank a little depending on my seat-o-the pants assessment of the situation. Like how heavy is the barrel, how flimsy the action, how flimsy the stock.

An aluminum chassis is quite stiff.

The B&C fiber reinforced foam stock my kids rifle is in is the opposite of stiff. It benefitted from having some support forward of the recoil lug.
The Kimber 84 Montana actions are pretty flexible. I wouldn’t hang a heavy barrel off of one of those, but if I did my first swing would probably include a bit of shank support.

In most cases I don’t bed the shank.

I’ve had a few cases where removing the bedding under the shank improved accuracy, and a few where adding it helped.

Some rifles like barrel pressure points (speed bumps) and some don’t.

Some outfits bed the entire barrel. NULA and Fieldcraft come to mind. Those rifles tend to be very accurate.

 

[Wrench]

I've done it virtually every way possible a few times. I have a rem mountain contour that is still full length bedded because that gun was most consistent that way.

I honestly cannot shoot the difference if there is one...when working with good components.

 

[LRI_Chad]

When I worked for Anschutz in the 90s, I'd cast a support block 1-1/2 inches beyond the face of the receiver when fitting up a 660mm barrel as it seemed to help with supporting the longer tubes. (Anschutz 54 receivers aren't all that big)

I've never seen any benefit on centerfire guns, though.

 

[Nick992]

I'm a fan of free-floating barrels. I agree with WeiserBucks though, I haven't seen any performance differences between the various options.

 

[Kimmo H]

I don't personally see any benefit of bedding the shank in most applications, but there are certain drawbacks to it. For example if you have more than one barrel for the action used, or if you ever take the barrel off and put it back on, how can you be 100% sure it goes the exactly same like in thousandths? Also the barrel heats when shot with a lot, expanding the shank a tiny amount, wich *could* induce stress.

The above is more of an issue on paper than in the real world, but still. I have done bedding jobs both ways, and have experimented by bedding the shank too at first, test firing, removing the bedding from underneath the shank after and re-test firing with the action bedding. I have yet to see removing the bedding from the barrel channel make the groups any worse on any of the guns I've tried it on.

Thats why I tape over the barrel shank to give it some clearance, and if the job allows I'll clean up that area by sanding, tapering off the bedding compund beneath the barrel to avoid any sharp corners. Sometimes I leave the bedding nearly untouched if that is necessary aesthetically, leaving just the 2 layers of plastic masking tapes worth of clearance around the shank.

Bedding has to be one of those things that can be done well in numerous different ways, and everyone who does it a lot will develop their own way that works for them. General rules apply, clearance is needed in certain parts for a truly stress free bedding, but the ways of achieving that are numerous.
Bad bedding jobs are a different matter alltogether that I won't even start to go in to

 

[SDHNTR]

I have no opinion or experience with chassis thingamajigs. I’ve only bedded real hunting rifles, lol.

On those, put me in the “it doesn’t matter”camp. At least if we’re talking about only bedding the recoil lug vs bedding the lug and an inch or so up the barrel shank. I just put an adequate amount of goo into the lug recess and if it spooges out and up the barrel channel an inch or so, so be it. As long as it cures in a uniform manner, I just leave it. You can always sand it down for a little clearance after curing if desired. I used to build tape or clay damns to keep epoxy from flowing forward and I’ve even milled out the epoxy back to the receiver after it’s cured. I’m not convinced it makes a difference either way. Just extra work.

 

[Wapiti1]

The scientific reason is that in stocks that are wood or plastic (fiberglass, carbon fiber, etc), the added length of bedding is supportive and stiffens that section of the stock. The action can and will flex along its length and the plastic or wood isn't stiff enough to fully control it. By bedding the barrel shank, you reduce that flexing.

In an aluminum chassis the action has rigid, or more rigid support, and the shank bedding isn't needed. To a point. If you hang a 30" 1.20" diameter straight taper barrel off the end, you'll bend the action with no barrel support.

Jeremy

 

[kbar]

I’ve been eyeing a chassis, but have been wondering the same thing you’re asking. Sorry not much help