.33 Newton Wildcat (aka?)


.33 Newton for lack of any other info. Is there any other nifty name for this one?
Case Length = 2.510 (about full length for .35 Newton)
Bullet Dia. = .332
O.A.L. = an impressive 3.735
27 Deg. Shoulder Angle.

Thanks, Dave


There is still disagreement whether or not the 33 Newton existed as a factory cartridge. If it did, I have never seen or heard of a 33 NEWTON headstamp.

As a wildcat it does exist. I have one virtually identical to yours. It is made from the same Speer 35 NEWTON brass. Mine is loaded with a two-diameter .338" bullet. It (bullet) looks like one of the old Nosler bullets that came out when the 338 Win Mag was introduced.

So, yours could be a 33 NEWTON with a 333" bullet since they (bullets) were used by many 33 caliber fans. It looks like one of the old Barnes QT (Quick Twist) bullets that were popular in several wildcats after WW II.

A nice cartridge, whatever it is.

That case head size (.525") has become popular among long range Benchrest shooters who make their wildcats from the 8x68mmS brass from RWS.


Does your .33 Newton bullet, have a wire core?


I see nothing but a typical lead tip, but maybe I’m missing something?


Thanks for the great info. A .33 Newton it shall be called…Any idea of the bullet weight if it’s a Barnes as you suggest?

The 14th ed. of Newton’s 1920 catalog section as reproduced in COTW is the only reference I have seen on a .33 Newton. 200gr. @ 3000fps.


The ECRA data CD has the following info:

.33 Newton

Country USA
Weapon Rifle, carbine
Notes From .300 H&H Magnum Lathe turned

Bibliography :
Donnelly J.J. - The Handloader’s Manual of Cartridge Conversions [384]

Specimen # 1 Donnelly - Manual of cartr. conv. 384



I don’t have the Donnelly book. I’ve heard of it but have not seen one. Is it simply a guide on how to make one case from another ?

It would seem odd that someone would go thru the trouble of converting an H&H case to a Newton given all of the NAC, Western, and Speer brass that is available. At one time Huntingtons (RCBS) even offered a basic case, made by Hirtenberger, I believe.


I could only guess at what the bullet might weigh. 300 grains? Barnes QT bullets were very long and heavy for their caliber and required a very fast twist barrel to stabilize them. They had a copper jacket.

You may be able to get a fair idea of the weight by weighing the cartridge and subtracting the case weight and a reasonable powder weight. The case should weigh about 280 grains and the powder another 70 grains. But the number you come up with would be nothing more than a SWAG. Mine has a 275 grain bullet and weighs 620 grains total.


Ray, I don’t have the Donnelly book either, all the info I gave comes from the ECRA disk.


Thanks for the additional info.


Likewise. Thought you may have had an old Barnes catalog. I was just curious as it is heavy for caliber no doubt. With the bullet weight and required twist, I bet that made for some torque on launching!