MBWT Data Comparisons (Damascus and Fluid)

[Dean Weber]

Dr. Drew Hause and I have been sharing some thoughts about MBWT, especially thickness at the chamber/FC juncture. I decided to begin cataloguing my measurements to share with Dr. Hause. Thought some of you may be interested as well. I will add more as I build out the details.

Details:
- Measurements were completed using Hosford Barrel gauge and Skeets bore gauge
- I suspect #12 to have been altered (chambers lengthened)
- I found it especially interesting to see same gauge, different weight compared closely to see differences in thickness
- Another interesting point is the observation of the steep angle of the forcing cone in many of the Parkers

[Dean Romig]

Interesting stuff Dean. Have you ever seen the plotting graphs and charts Austin Hogan did on Parker chambers , bores and chokes?

I have several of them nd will post a few on another thread so as not to take your thread off on a different tangent.





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[Dean Weber]

No, I have not had the opportunity to review those charts. I would like to see them.

[Dean Weber]

Someone asked via PM my process for MBWT. MBWT = the minimum reading I get anywhere on the barrel. I take many measurements with the gauge and record the thinnest reading at any point. Further, nearly all my MBWT readings occur near a rib. This is also true for the 9" from muzzle reading.

[Dean Romig]

Originally Posted by Dean Weber

Someone asked via PM my process for MBWT. MBWT = the minimum reading I get anywhere on the barrel. I take many measurements with the gauge and record the thinnest reading at any point. Further, nearly all my MBWT readings occur near a rib. This is also true for the 9" from muzzle reading.

That's not at all surprising given that the final/finish striking of the barrels was done after the ribs were laid.
This set of Grade-6 Damascus barrels not only are chamfered at the muzzles but you can easily see that the tubes are considerably thicker between the barrels and under the ribs and the striker, while maintaining the 'concentric' contour, must keep them thin while not going too thin.


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[Randy Roberts]

Very interesting Dean. Concerning the steep angle of the forcing cones you mentioned what length are you generally seeing on the cones? I assume the ones with the steep angles would be shorter possibly ?

On a side note of all the Parkers that I have measured that were original I have been extremely impressed with the craftsmanship in them and how concentric they were. The one exception would be a truly mint Remington era 16 gauge that has measurements all over the place. It makes me wonder if it was a Friday gun.

[Dean Weber]

Randy,
I don’t document that measurement unless it presents longer than expected, but I would say 5/8-3/4 is the range where I see the nose of the cone. I should also like to confirm my statement as many, not all. When we see .010 or better in thickness change in a 3/4 inch travel....that is steep to me. On the other hand, other barrels in the sample only change a few thousandths. I only included one Parker where I believe the chamber has been lengthened.

I have had a different experience with concentricity. I find a good number of my original, maybe even mint Parkers to have inconsistencies in MBWT at the same longitudinal point.
Best,
Dean

[Randy Roberts]

Thanks Dean. I should clarify that when I was referring to Parker barrels as being very concentric I intended that to mean generally along the entire length and not at any one longitudinal point. At any one point I have seen the same inconsistencies that you have mentioned.

[edgarspencer]

One gun I'd like to see more data on is a 16ga 0 frame. Larger bore, smaller frame= less wall.
I have one, and will attempt to get some meaningful numbers after the next coffee.

[Dean Weber]

Edgar,
I would like you to share your numbers as well!

Your point is very valid and clear when you study like, original guns next to each other they provide for an interesting discussion. For example subjects 10 and 11. Both are original guns on a 1 frame (1 28" and 1 26"). The 28" weighs 5oz less than the 26". They have similar MBWT. Yet the 28" chamber/fc measurement is .020 less. One has a steep FC and the other a more gradual one of a few thousandths.