The Real Guns CZ 550 FS Goes 375 Ruger Part I-Only Europeans really like the 9.3x62

A lot of folks skip over the idea of owning a functionally customized firearm, because they assume all custom rifles come with a price tag similar to the functional custom’s far distant cousin, the superfluously customized firearm. Personally, I’ve not had the desire to own a superfluous custom for several reasons – The first, I can’t afford one. The second, if a modification doesn’t significantly improve a firearm’s performance, it isn’t of much interest to me. The third, gunsmiths with the capacity to do superior work are far and few between. When you can find one, even if they turn more routine modifications relatively quickly, the artsy stuff has lead times measured in light years. I’d fear placing a large deposit on a fancy lad’s rifle, then dying of old age before it is completed.

Only Europeans really like the 9.3x62mm

Europeans, and American’s who pretend to be Europeans, have a love affair with the 9.3x62mm. And why wouldn’t they? It is the 1905 invention of Otto Bock, a Berlin gunsmith and it made its reputation as a low cost conversion of military firearms for farmers immigrating from Europe to Africa. So the cartridge has everything Europeans love: crusty old, of German origin, the pretense of frugality, the inference of African hunting, and the round has nothing to do with “those damn Americans”. I, on the other hand, have the  American inclination that a little American ingenuity can go a long ways toward correcting all things European. I figured if Ford can fix Jaguar by installing a Ford drive train in those British oil leakers, even if they failed at reforming British labor and had to sell the company, why not follow suit with firearms? It seemed it was time to rid my CZ 550 Full Stock of its 9.3x62mm Europeanen.. ness and convert it to an all American .375 Ruger. Yeah, you heard me right, Bucko!

For the sake of comparison…

On a less jocular note, the 9.3x62mm is an excellent cartridge, putting out a good deal of power with efficient use of propellant. The 0.366″ diameter bullet in heavier weights have good sectional density for enhanced penetration. Handloaders, unfortunately, typically find that bullet selection is narrow and expensive and  velocity falls off sharply as bullet weight increases to the popular 286 grain level.

The .375 H&H has a cartridge overall length of 3.600″, which means it requires a magnum length action, which suggests a heavy and costly firearm. The .375 Ruger is a 3.340″ length cartridge which requires only .30-06 Springfield length action, which means, compact, lighter, less costly and the availability of lots of donor rifles. Only communists prefer the .375 H&H.
 

Weight & Measure	30-06 Spgfld	9.3x62mm	.375 H&H	.375 Ruger
COL	3.340	3.291	3.600	3.340
Case Length	2.494	2.441	2.850	2.580
Case Diameter	0.471	0.476	0.513	0.532
Capacity H2O	68	78	95	99
MAP PSI	60,000	56,000	62,000	62,000

Why the CZ 550 Medium Magnum Full Stock?

Principally, because I already owned one and, after watching Oprah, I realized I had been denying my distain for the 9.3x62mm for too long and it was time to stand up and make a statement. Not as important, but part of the mix in consideration, the CZ 550 medium magnum action is strong enough to routinely be utilized on guns chambered for the 7mm Remington and .300 Winchester magnums; high pressure and large case heads.

The CZ’s 30-06 Springfield length square bridge action has integral 19mm dovetailed and keyed scope mounts. The magazine capacity is three rounds, there is a steel hinged floorplate, a three position safety and a fully adjustable single set trigger. Important for this conversion, the CZ 550 has double recoil lugs and cross bolts to minimize the chance of a broken stock. Even the swivel set, a front quick change bead and fully adjustable rear sights are in place and appropriate for a heavy hitter of the type planned. The CZ 550 Full Stock is also, and I believe it matters, a good looking firearm and relatively compact even in comparison to the diminutive Ruger short barrel M77 International, pictured top/below. Basically, everything anyone could want in a donor rifle is here.

My true talent lies in shipping and receiving…

The most important thing I know about customizing a rifle is buying parts from Brownells and putting the guns and parts into a box and shipping it all to Dennis Olson.

Dennis Olson
P.O. Box 337
500 First Street
Plains, Montana 59859
406-826-3790

Brownells; #237-375-124 a Douglas 375 1-12 Twist Chrome Moly #4 Contour Ultra Rifled Barrel was selected for this project. It is 26″ long, eight groove buttoned rifled, stress relieved and straight to 0.0005″. The contour was selected because it didn’t have a lot of excess material, but it could be finished close to the factory barrel dimensions. This minimized stock barrel channel rework and allowed the barrel to be cut to 20½” just like the factory piece. The Brownells’ barrel price at the time of this writing was $223.

Dennis is a busy guy and doesn’t talk a lot. He is polite, as is everyone associated with his business, but he has so much experience that it doesn’t take a lot of chatter to get on the same page in terms of work to be done. My basic request was:

• Rebarrel and chamber for the .375 Ruger

• Contour the barrel so that it is as close as possible to a factory match

• Move over all of the original barrel hardware; sights, recoil lug

• Chamber stamp rather than engrave the barrel

• Refinish the gun as necessary to make it all match.

When I shipped the gun to Dennis, I sent along factory ammo and examples of bullet extremes I intended to handload so he could ensure the rifle would cycle reliably as a 375 Ruger. Dennis said four weeks lead time and that’s how long it took. No nagging, no expediting, or any of the other aggravating situations that so often are associated with getting work done.

All of the metalwork, woodwork and bluing were as meticulously finished on surfaces normally covered by the stock as they were on exposed surfaces. For the record, I am a paying retail customer and  Dennis operates a business that doesn’t need promoting. The same quality of work and honoring of schedules has applied to all of our earlier projects that have passed through his shop.

The finished product…

Above – The bolt face and extractor claw were opened up to accommodate the increase in case head diameter. Above right – The barrel finish matched the original, somewhere between gloss and satin. The barrel finished contour was close enough in radius for the sighs bases to fit without a gap and the #6 screws eliminated metric hardware while providing greater security. The .375″ caliber muzzle was slightly larger than the 9.3’s .366″ so the OD was slightly larger to maintain bore wall thickness. The end cap has to be opened up proportionally and refinish with the end result a better fit than the unmodified factory piece.

The magazine rails were opened up so that the larger cartridge would feed reliably. The barrel channel, approximately the last eight inches or so, was opened up slightly to accommodate the  slightly larger barrel diameter. The cuts are nicely transitioned and smooth, the wood was resealed to keep out moisture.

Back at our shop a couple of finishing touches were added before moving on with the project. A steel follower replaced the factory plastic piece and a Bushnell Elite 6500 1.25-8×32 scope was installed on Warne steel rings made for the proprietary CZ mount system. I think these optics are perfect for this cartridge and rifle; the right magnification range, a bright image and range of adjustment that only a 30mm tube can deliver. The scope will be covered in detail in a separate piece.

Up next…

There is some checking to do on critical measurements like freebore and headspace before serious handloading development can take place, but we’re almost there. Hopefully loads can be developed from very light to very heavy for bore as the cartridge is very flexible.

Ops checking the gun was… fun. I ran some factory 270 grain loads and a couple of 350 grain handloads through the gun. The first shot was squeeze off with my brain thinking 9.3x62mm and my shoulder thinking 375 Ruger. At approximately 7½ lbs and with 71 ft/lbs of recoil, the CZ is now… attention getting, but certainly not objectionable to shoot. It is a light, compact, fast pointing rifle that should be able to handle anything I’d ever encounter while hunting. The next step is to assemble some optimal handloads and see how accurately the gun can shoot.

 

The Real Guns CZ 550 FS Goes 375 Ruger Part I
The Real Guns CZ 550 FS Goes 375 Ruger Part II