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Gunsmithing Chamber protrusion

sharac

Sergeant
Full Member
Minuteman
Dec 8, 2008
781
756
47
Slovenia
Hi,

when ordering Lothar Walther barrel there is an option for chamber protrusion and i've asked them what it means and response was:

"the protrusion is the differents between the ending of the barrel and the end off the cartridge (gauge)
it can be from minus to plus. "

As far as i understand what good would that be other for final headspacing (have a bit of extra meat to grind off and fine tune headspace to clients liking). I can't imagine -protrusion and having some part of the case exposed be a good thing?
 
Re: Chamber protrusion

Sounds like you're buying a short chambered barrel that you have to run a finish reamer to cut the last .030" to .050" to reach chamber depth and establish headspace with your bolt and gauges.
 
Re: Chamber protrusion

Yeah my thoughts exactly however i'm baffled by ability to have negative protrusion which would by my understanding leave case exposed aka "short chamber". I really never heard of this term and thats why i asked them (not big help their answer was
smile.gif
) to explain...
 
Re: Chamber protrusion

With a negative protrusion you wouldn't need the reamer, you'd just have to face off the barrel until the chamber was the proper length.
 
Re: Chamber protrusion

I think i'm having a doh! moment...

So basically protrusion means whether the chamber is either totally in spec (0) or chamber too short (+) which needs reaming to spec or desire and too long (-) which needs facing off the end of the barrel to spec or desire.
 
Re: Chamber protrusion

What rifle are ya puttin' it on?
Even at "0" there's nothing to say it will be head-spaced correctly in your rifle.

I don't know if you're using a lathe, but removing much material by hand turning a reamer isn't a good idea(from what Ive seen anyways)
I try to avoid ever reaming by hand. I will remove one or two thou by hand if I have to but any more than that and I put it back in the lathe.
 
Re: Chamber protrusion

Definitely it would be done by gunsmith (tikka action) i was just wondering what does the term mean when ordering as obviously i'd prefer that barrel is only faced and not reamed. So when i'll order i will take with some extra meat and then gunsmith will headspace to correct length.

Thanks a lot for all your help.
 
Re: Chamber protrusion

It depends on if you want to use their reamer as the final dimensions or if you want to basically just have it roughed in and then have your reamer determine what the final chamber looks like.

Personally I'd much prefer an unchambered barrel. You're going to have to take it to a smith anyway so why introduce the possibility the factory cut the short chamber non-concentric with the bore? Walther produces thousands and thousands of barrels, and they certainly do a pretty damn good job, but that is not the sort of environment that lends itself to meticulous attention to detail on every single barrel. Not in the manner that most gunsmiths do, at least.
 
Re: Chamber protrusion

Is it possible that they offering a completely finished and chambered barrel and they are asking you to do the math to detirmine your headspace measurement and they will fit it to that so all you have to is screw it on? Not something i would use but that my take on it.
 
Re: Chamber protrusion

Nope i believe they offer only this as without action there is no way to "blindly" trust customer for correct measurements (don't even know if its possible to do "dry measurements" to such precision - i'm almost positive that not even best gunsmith is able to do such thing) as there is always some either tension on threads or some other minor thing that can ruin your day.

Something you over the pond won't understand but here in Europe (at least in Slovenia but elsewhere also kinda same) there aren't many gunsmiths whom one can trust to be able to ream barrel to spec. Locally i'm not even sure how many reamers are available (perhaps classic hunting and common military). Some time ago there were many good smiths around (Ferlach School) and nowadays a lot of the knowledge is gone. So having Lothar do the reaming may be best option for us - unfortunately
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.