Re-chambering question in 7mm

bjornf16

bjornf16

Well-known member
Need some gunsmithing expertise.

I have a 7mm Weatherby barrel that has excessive headspace (closes on field gauge) on a barrel that cannot be "setback" (aftermarket Blaser R8 barrel).

Can a 7mm Weatherby be re-chambered to 7mm STW (or any other cartridge for that matter)?

Thanks,
Björn
 
28N would be acceptable to me...but I thought the belt from 7mm Weatherby would eliminate a non-belted cartridge.

Edit: I looked up the 28 Nosler case. Based on 300 RUM, it does have a wider body than the 375 H&H based cartridges. I will look into pursuing 28 Nosler over the 7mm STW.

Thanks @hand skills
 
bjornf16 said:
Need some gunsmithing expertise.

I have a 7mm Weatherby barrel that has excessive headspace (closes on field gauge) on a barrel that cannot be "setback" (aftermarket Blaser R8 barrel).

Can a 7mm Weatherby be re-chambered to 7mm STW (or any other cartridge for that matter)?

Thanks,
Björn
Click to expand...
Stw along with anything with a belt is the problem. Your belt was too deep, it head spaces off the belt.
 
bjornf16 said:
Need some gunsmithing expertise.

I have a 7mm Weatherby barrel that has excessive headspace (closes on field gauge) on a barrel that cannot be "setback" (aftermarket Blaser R8 barrel).

Can a 7mm Weatherby be re-chambered to 7mm STW (or any other cartridge for that matter)?

Thanks,
Björn
Click to expand...
Why can't you size your cases to space from the shoulder?
 
Edd said:
Why can't you size your cases to space from the shoulder?
Click to expand...
When I say “excessive”…I mean really excessive. Bolt would close on 7 layers of painters tape on virgin cartridge base.

To boot, this “new” barrel has pitting in the chamber.

“Gunsmith” has ghosted; I’m awaiting credit card decision on refund. I’d rather just send it back for a properly headspaced 7 Wby, but in case I end up eating this, I’m looking for options.

Unfortunately, the same “gunsmith” sent me a 300 WSM barrel with same issue (closes on field gauge). Amount of headspace isn’t as bad as the Weatherby, so maybe I can blow virgin brass shoulder out. I tried 62 gr of H4350 (1 gr above min load) with 175 MK and had to hammer the bolt with palm to open.

Same “gunsmith” sent me a really nice 22CM barrel last year. Batting .333


IMG_0926.jpeg
 
bjornf16 said:
Need some gunsmithing expertise.

I have a 7mm Weatherby barrel that has excessive headspace (closes on field gauge) on a barrel that cannot be "setback" (aftermarket Blaser R8 barrel).

Can a 7mm Weatherby be re-chambered to 7mm STW (or any other cartridge for that matter)?

Thanks,
Björn
Click to expand...
If you are looking to "salvage" barrel, the 7MM STW just might work. Might clean up chamber since dimensionally the STW case body is slightly larger.

The real question is the overall quality of the barrel. Who made the barrel? What is the twist? What is the rifling? 6? 5R? Something else? Blaser is wonderful rifle, seems like you have a jack handle instead of a barrel. I don't think I would want to throw money at a barrel of unknown base quality.

Interesting thought, are you sure you have a 7MM Wby chamber? Have you measured the fired case dimensions to SAAMI? Almost sounds like you might have a STW? The STW is significantly longer in headspace. Just a curious thought. Back to my beer.


IMG_1745.jpegIMG_1746.jpeg
 
PBB barrel, 8 twist chambered by the “gunsmith”, marked 7mm Weatherby.

Don’t care for the Blaser option in twist rates.

It would be interesting to try to chamber STW.
 
It would not be first time barrel reamed with wrong reamer.

Well my experience with PBB has been stellar. I have had 5 barrels from them. All shooters. I would call them to see if they would consider looking at it. It's not their problem but they do have good CS. Talk to Bryce. They might have some thoughts to help.
 
Brass always issue BUT here ya go for 7MM RUM
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Muddyboots said:
Interesting thought, are you sure you have a 7MM Wby chamber? Have you measured the fired case dimensions to SAAMI? Almost sounds like you might have a STW? The STW is significantly longer in headspace. Just a curious thought. Back to my beer.
Click to expand...
The headspace dimension on a 7mm STW and a 7mm Weatherby are exactly the same.
 
I just noticed that the SAAMI drawing for 7 STW has .003” more headspace at belt than the 7 Wby…

7 STW: .220-.227”
7 WBY: .220-.224”
 
Edd said:
They headspace on the front of the belt.
Click to expand...
Yes, they do from "technical" position but if the shoulder "headspace" dimensions are this far off the entire headspace chamber dimension is off. The headspace for a belted mag is also the entire dimension of the chamber. If the belt was the "sole" headspace requirement, SAAMI would not have shoulder dimensions. The belt does not exclude the requirement to meet SAAMI chamber dimensions. This is the very reason Peterson brass came out with 300WM and 7MM RM long versions of brass to better meet the entire chamber dimensions from SAAMI. On first firings of std brass, common to have 0.008 or more stretch on regular brass because of not being produced closer to SAAMI total headspace chamber specs. This leads to early brass failure. The Peterson brass is approx 0.003 short of SAAMI spec off shoulder thus better fit less stretch. Anybody that shoots a belted mag, headspaces off shoulder for FL resizing.

This chamber is either excessive headspacing or possibly wrong reamer.
 
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