Sorry if this is overly long for some…..things are slow and it’s been raining again so decided to stir the pot a bit!!!

It’s been an interesting few months reviewing all of the thread conversations relating to the Newton rifles and cartridges – particularly the Newton cartridges. While studying the 375 Ruger cartridges my attention was again drawn to the .30 Newton based cartridges.

There is a tremendous volume of conflicting information relating to the .30 Newton cartridges and derivates on the internet! It appears, at least to me, that some though not all of this conflict relates to manufacturing variances of the Newton cartridges by different manufacturers being taken as the basis for chambering dimensional information vis-à-vis utilization of actual chambering information.

So I thought that I’d list the true Newton’ chamber dimensional data for the .30 Newton parent cartridge cases:

1) 28 Newton: bore/groove: .280â€/.288â€, Chamber Diameter @ Rim/Base: .531â€/.531â€, Shoulder Diameter: .503â€, COAL Min/Max: 2.530â€/2.533â€
2) 30 Newton: bore/groove: .300â€/.308â€, Chamber Diameter @ Rim/Base: .531â€/.531â€, Shoulder Diameter: .503â€, COAL Min/Max: 2.530â€/2.533â€
3) 33 Newton: bore/groove: .330â€/.338â€, Chamber Diameter @ Rim/Base: .531â€/.531â€, Shoulder Diameter: .503â€, COAL Min/Max: 2.528â€/2.530â€
4) 35 Newton: bore/groove: .350â€/.358â€, Chamber Diameter @ Rim/Base: .531â€/.531â€, Shoulder Diameter: .503â€, COAL Min/Max: 2.530â€/2.533â€
5) 40 Newton: bore/groove: .400â€/.408â€, Chamber Diameter @ Rim/Base: .531â€/.531â€, Shoulder Diameter: .503â€, COAL Min/Max: 2.530â€/2.533â€

Though Newton tool room/mule rifle(s) were manufactured for the 28 Newton, none were commercially manufactured in the original specification. During testing Newton determined it to be severely overbore capacity for the powders available during its development period for optimum performance.

Though Newton tool room/mule rifle(s) were manufactured for the 33 Newton, none were commercially manufactured due to insufficient interest in this caliber in the USA in the post WWI era.

Though Newton tool room/mule rifle(s) were manufactured for the 40 Newton as designed, none were commercially manufactured. However four known Newton rifles were manufactured utilizing bushing/sleeved 405 Winchester barrels - therefore using a bore/groove diameter of .405â€/.411â€; the remaining case dimensions were as originally designed.

Good luck “jeffeosso†with obtaining your “AR†headstamped brass…Jamison has had 6K .30 Newton cases on backorder from reloading suppliers for about one year with no target date for production! Same status for Quality Cartridge.

Thanks to Hornady/Ruger for the .375 Ruger cartridge cases as, lacking a .30/.35/.40 Newton production run by Jamison or QC, it is the perfect parent case to use for the .30 Newton derivative cartridge cases!!! Now if they just weren’t “out of stock†so often.

I want to publically thank Tom (bisonland/white bison on AR) for his emails pointing me to the few books that contain factual Newton information. My collection is increasing monthly inclusive of my stack of Newton catalogues (authorized copies of originals rather than the original copies) is growing and from whence the Newton’ chambering information is derived.

Cheers,
Jim