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Old November 15, 2020, 03:53 PM   #1
stagpanther
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What would you do?

OK--I'm faced with a dilemma and made a choice--though I'm not sure it was the right one--interested in what the groupthink has to say.

Last year a customer brought me a model 70 in 270 Weatherby magnum to work on, it was pretty beat up and the stock was a mess when I first got my hands on it. After a lot of work on it I got lucky and made and exceptional shooter out of it, in fact his extended family uses the gun frequently since everyone that uses it has been getting nice one-shot kills out to respectable distances. Something that makes me kinda proud when they report their successes.

Well, perhaps it's a case of "victim of success" but the customer bought another old 270 Weatherby magnum--this one a vanguard classic, which after talking to the folks at Weatherby I found out they (aka howa) only made it one year; in 1990. It's turned out to be quite a bit more work than I anticipated, right now I'm trying to smooth over some of the bore corrosion pitting to see if I can possibly "rescue" the barrel and maybe extend it's life.

Luckily, I kept some of the spent cases from the model 70 I worked on to use to make some bore-polishing cartridges with tubb's finishing kits. I also have a few cases of factory ammo that had already been fired through the vanguard.

When I checked the cases that had been fired through the Model 70, they would not chamber in the vanguard. At first I thought it was just a matter of adjusting the dies, but no matter what I did the case that had been fired through the model 70 could not be resized to fit in the vanguard. I don't have any gauges for any of the Weatherby magnums--but I do have a case gauge for a 300 win mag--and sure enough the case would not fit properly.

Bottom line, I suspect that there is a real possibility that the model 70 may have a headspace issue, although I won't know until I get it back in my hands. This rifle has already dropped several deer and a moose in the past few weeks and it's not going to go over well if I ask to "pull it out of circulation."

Short story long, I basically told the owner today that I felt there was a real potential danger of the rifle having a failure and that if it were my family I would not let my kids use it. He wasn't happy, but he said he would take it "off line."

I'm not even sure what the potential liability issues might be having done this--any thoughts?

PS--when I first got the model 70 I wasn't asked to check the headspace, only to clean the rifle up and zero the scope. In retrospect--even though it's a factory production rifle, is this something I should have "automatically" done even if not asked to?
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Last edited by stagpanther; November 15, 2020 at 07:04 PM.
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Old November 15, 2020, 08:01 PM   #2
xtriggerman
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If the bolt closes without drag on a fresh cartridge, and no sign of excessive pressure on fired brass, Let it be. Back when I used to chamber barrels, Belted mags all ways ran some what on the + side of headspace. I liked running them tight on a go gauge because of it.
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Old November 15, 2020, 09:51 PM   #3
HiBC
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I have not looked up the chamber drawings to verify,but my understanding is the 270 Weatherby is a derivitive of the 300 H+H case,like most belted magnums.
Remember the H+H belted case headspaces on the belt,not the shoulder.
The cartridge dwg would be .220 (-.008) and the chamber dwg would be .220 to .227.
The headspace gauge can be a button ,one .220 and one .227 long. for the chamber "Go" and "No Go" (Check real dwg numbers,this is for illustration)

In my experience,it is not unusual for belt chamber headspace to be generous.
The bias will typically be toward failsafe chambeing. If something is going to bite you,the cartridge must chamber.

With the belt holding headspace,reloading brass life is not a concern of the ammo maker or rifle maker. It has to go "bang " once.

Its not unusual to have generous fireform room at the shoulder.

Looking at the numbers,in spec short brass in a in spec long chamber has .015 to set back. Thats a clue about belted magnum stretch rings.

So experience handloaders learn to ignore the belt and set up their sizing die for a controlled head clearance based on the shoulder in one rifle.Maybe .002.

When I was shooting a Husky 7mm Rem mag,and a M-70 7mm Rem Mag,I just bought Federal nickel plated brass for the Husky and WW for the M-70.

They WERE different. I sized them to fit the rifles. And segregated the ammo.

I do appreciate that you are conscientious. I insist on my work meeting headspace specs. But you don't know to tell that rifle owner to red tag his rifle unless it fails not only the "Go" and "No Go" guages,but the "Field" too,which is more generous. While anything is possible.it would be rare for the headspace to be out of spec,at the belt.
But its to be expected that the chamber shoulders may have conflict.

What I would do if the rifles were mine

With a drawing and a lathe and a 0 to 1.000 mic,you can spin up useful belt button headspace "Guages" Or,you can buy them. Check the belt headspace.And actually,to red tag a gun,it must fail the field gauge.

This will establish the GUN is legit. No red tag.

But now,show them stretch rings,the paper clip test,and teach them the advanced handloading skills to tailor ammo to the rifle,and get maximum case life. Ask how,if you aren't sure.

You ARE correct that loading one size ammo to fit two different belted magnums will likely be problematic. And the consequences may be case seperations after a few firings. The rifles will likely be within spec.

The answer is probably at the handloading bench.

Its unlikely you did anything questionable.

You are not the first to deal with an industry tolerance issue.. The gun's instructions will probably say "Don't shoot reloads"

FWIW to take in gunsmith work,particularly if you keep a gun overnight,an FFL is required. Maybe you have one. None of my business. I am an amateur hobbyist I do my own work,I don't take in any work.
I just keep me happy.

Last edited by HiBC; November 15, 2020 at 10:09 PM.
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Old November 16, 2020, 03:17 AM   #4
stagpanther
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Quote:
But its to be expected that the chamber shoulders may have conflict.
You nailed it right there, and I should have done that before I red tagged it. Upon closer examination of the cases fired in the model 70 I see that the case in the region of the base of the shoulder has expanded to .5 +/- .001 in many of the cases. Customer only shoots Weatherby (norma) factory ammo so reloading is not an issue, it's one and done for him. I'll also thoroughly wash the inside of a few cases and inspect with a borescope to make sure there are no stress lines to worry about. I went ahead and ordered a complete gauge set from PTG, so I'll "eat some crow" and apologize to the customer and simply request that he bring me the rifle to check when the gauges come in.

I just cleaned and borescope the inside of a case--no stress lines anywhere.

I foobarred.
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Last edited by stagpanther; November 16, 2020 at 04:14 AM.
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Old November 16, 2020, 08:18 AM   #5
Nathan
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First...what would this have told you?



It will tell you where the belt is in the chamber.

That said, you can buy a go and a no-go. That is for barrel fitting. Can you buy a field? Not that I’ve seen. That is your limit. You could check, but you were really asked to clean it up and shoot it.

What you are concerned about is shoulder position or maybe diameter. The old rifle’s case blew the shoulder forward and sizing back to match the other is hard. You may have to anneal the shoulder area and or use those fancy Redding shellholders to switch between rifles.

Have you measured the belt and just about the belt for both rifles? One chamber might be larger or egg shaped slightly. That would affect brass change between rifles.

Do factory fresh cartridges fit? Primer strikes ok? Primer pin protrusion in the 0.040-0.080” range? Primers appropriately flattened?

Bolt open and primary extraction work? Cases not separate upon firing?
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Old November 16, 2020, 10:03 AM   #6
stagpanther
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Thanx Nathan--HiBC I believe already nailed it, what I found measuring the cases--though not exactly definitive, is that there is likely a differential in the two chambers in shoulder cuts which, when allowances are "stacked" can account for the differences I'm seeing in case expansion between the model 70 and the vanguard. I also cleaned several cases and examined from within with a borescope and saw no signs of unusual flow or an area of incipient weakness, and considering the user only fires factory ammo one time, I contacted them and--after eating some crow--told them it was a false alarm but that 1) I wanted to measure the rifle when the complete set of PTG gauges come in (I've used most of them, but PTG's are the best IMO); and 2) if they experience any unusual difficulties feeding or extracting factory ammo to discontinue use and let me know.
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