375 Whelen Improved Go Gauge.

[Lbass]

I ordered a barrel for my 110 savage in 375 Whelen Improved (40* shoulder) about a month ago. I received the Go gauge today to use for headspacing. The shoulder on the go gauge is 17.5* instead of the 40*. Is this correct or have they sent me the wrong gauge. The etching on the side of it say, 375 Whelen ACK GO PTG. The tube even says .375 Whelen ACK 40 Deg. Thanks
And yes I checked on our comparator at work, It's 17.5* just like a Standard 30-06 brass.

[KRP]

Shoulder angle on the guage means nothing. The markings are correct so I would trust that it is. You have a comparator though so you probably have the tools necessary to check it.

[Lbass]

If the shoulder angle means nothing, What makes this gauge any different than a 30-06 Go gauge.

[Eric in NC]

If the shoulder angle means nothing, What makes this gauge any different than a 30-06 Go gauge.


Length at the datum line point on the shoulder is what you are measuring - not angle of shoulder. That is why you can use the parent cartridge (in this case a 30-06) GO as a no go guage in an AI chamber.



However my 375-06 AI go gauge does have what looks to be a 40 degree shoulder but it isn't a PTG.

Use the gauge, set the headspace, and if a 30-06 Go won't chamber, you are in good shape. You could also call PTG and ask if this is SOP for their Ackley gauges.

[Lbass]

I called PTG, the lady told me they don't make a 375 whelen gauge for the 40 deg.

[Lbass]

Manson Reamers Website,
We make our headspace gages for improved chambers according to Ackley’s recommendations. Our improved “GO” gage is .004”/.006” shorter than the standard GO gage, and has the same shoulder angle. The standard GO gage should be used as a “NO GO” in an improved chamber.
It has been suggested that headspace gages for improved chambers should be made with the same shoulder angle as the chamber—thereby making them easier to use because of contact along the entire shoulder. Gages made in this manner are caliber-specific; that is, they may be used for gaging only the caliber and specific neck size for which they were designed—they can’t be used with improved versions of any other bore size.
Gages made according to Ackley’s guidelines may be used to headspace any caliber based upon the original case. For instance, 30-06 Improved gages—made the way we make them—may be used to headspace all ’06-based chambers from 22-06 Imp. through 35 Whelen Imp., or larger.

Much more helpful than the PTG phone call, and answered my next question in the last paragraph there.